1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.  Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 */
26
27/*
28 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
29 * (C) Copyright IBM Corp. 1996 - 1999 - All Rights Reserved
30 *
31 * The original version of this source code and documentation
32 * is copyrighted and owned by Taligent, Inc., a wholly-owned
33 * subsidiary of IBM. These materials are provided under terms
34 * of a License Agreement between Taligent and Sun. This technology
35 * is protected by multiple US and International patents.
36 *
37 * This notice and attribution to Taligent may not be removed.
38 * Taligent is a registered trademark of Taligent, Inc.
39 *
40 */
41
42package java.util;
43
44import dalvik.system.VMStack;
45import java.io.IOException;
46import java.io.InputStream;
47import java.io.InputStreamReader;
48import java.lang.ref.ReferenceQueue;
49import java.lang.ref.SoftReference;
50import java.lang.ref.WeakReference;
51import java.net.JarURLConnection;
52import java.net.URL;
53import java.net.URLConnection;
54import java.nio.charset.StandardCharsets;
55import java.security.AccessController;
56import java.security.PrivilegedAction;
57import java.security.PrivilegedActionException;
58import java.security.PrivilegedExceptionAction;
59import java.util.concurrent.ConcurrentHashMap;
60import java.util.concurrent.ConcurrentMap;
61import java.util.jar.JarEntry;
62
63import sun.reflect.CallerSensitive;
64import sun.util.locale.BaseLocale;
65import sun.util.locale.LocaleObjectCache;
66
67
68/**
69 *
70 * Resource bundles contain locale-specific objects.  When your program needs a
71 * locale-specific resource, a <code>String</code> for example, your program can
72 * load it from the resource bundle that is appropriate for the current user's
73 * locale. In this way, you can write program code that is largely independent
74 * of the user's locale isolating most, if not all, of the locale-specific
75 * information in resource bundles.
76 *
77 * <p>
78 * This allows you to write programs that can:
79 * <UL type=SQUARE>
80 * <LI> be easily localized, or translated, into different languages
81 * <LI> handle multiple locales at once
82 * <LI> be easily modified later to support even more locales
83 * </UL>
84 *
85 * <P>
86 * Resource bundles belong to families whose members share a common base
87 * name, but whose names also have additional components that identify
88 * their locales. For example, the base name of a family of resource
89 * bundles might be "MyResources". The family should have a default
90 * resource bundle which simply has the same name as its family -
91 * "MyResources" - and will be used as the bundle of last resort if a
92 * specific locale is not supported. The family can then provide as
93 * many locale-specific members as needed, for example a German one
94 * named "MyResources_de".
95 *
96 * <P>
97 * Each resource bundle in a family contains the same items, but the items have
98 * been translated for the locale represented by that resource bundle.
99 * For example, both "MyResources" and "MyResources_de" may have a
100 * <code>String</code> that's used on a button for canceling operations.
101 * In "MyResources" the <code>String</code> may contain "Cancel" and in
102 * "MyResources_de" it may contain "Abbrechen".
103 *
104 * <P>
105 * If there are different resources for different countries, you
106 * can make specializations: for example, "MyResources_de_CH" contains objects for
107 * the German language (de) in Switzerland (CH). If you want to only
108 * modify some of the resources
109 * in the specialization, you can do so.
110 *
111 * <P>
112 * When your program needs a locale-specific object, it loads
113 * the <code>ResourceBundle</code> class using the
114 * {@link #getBundle(java.lang.String, java.util.Locale) getBundle}
115 * method:
116 * <blockquote>
117 * <pre>
118 * ResourceBundle myResources =
119 *      ResourceBundle.getBundle("MyResources", currentLocale);
120 * </pre>
121 * </blockquote>
122 *
123 * <P>
124 * Resource bundles contain key/value pairs. The keys uniquely
125 * identify a locale-specific object in the bundle. Here's an
126 * example of a <code>ListResourceBundle</code> that contains
127 * two key/value pairs:
128 * <blockquote>
129 * <pre>
130 * public class MyResources extends ListResourceBundle {
131 *     protected Object[][] getContents() {
132 *         return new Object[][] {
133 *             // LOCALIZE THE SECOND STRING OF EACH ARRAY (e.g., "OK")
134 *             {"OkKey", "OK"},
135 *             {"CancelKey", "Cancel"},
136 *             // END OF MATERIAL TO LOCALIZE
137 *        };
138 *     }
139 * }
140 * </pre>
141 * </blockquote>
142 * Keys are always <code>String</code>s.
143 * In this example, the keys are "OkKey" and "CancelKey".
144 * In the above example, the values
145 * are also <code>String</code>s--"OK" and "Cancel"--but
146 * they don't have to be. The values can be any type of object.
147 *
148 * <P>
149 * You retrieve an object from resource bundle using the appropriate
150 * getter method. Because "OkKey" and "CancelKey"
151 * are both strings, you would use <code>getString</code> to retrieve them:
152 * <blockquote>
153 * <pre>
154 * button1 = new Button(myResources.getString("OkKey"));
155 * button2 = new Button(myResources.getString("CancelKey"));
156 * </pre>
157 * </blockquote>
158 * The getter methods all require the key as an argument and return
159 * the object if found. If the object is not found, the getter method
160 * throws a <code>MissingResourceException</code>.
161 *
162 * <P>
163 * Besides <code>getString</code>, <code>ResourceBundle</code> also provides
164 * a method for getting string arrays, <code>getStringArray</code>,
165 * as well as a generic <code>getObject</code> method for any other
166 * type of object. When using <code>getObject</code>, you'll
167 * have to cast the result to the appropriate type. For example:
168 * <blockquote>
169 * <pre>
170 * int[] myIntegers = (int[]) myResources.getObject("intList");
171 * </pre>
172 * </blockquote>
173 *
174 * <P>
175 * The Java Platform provides two subclasses of <code>ResourceBundle</code>,
176 * <code>ListResourceBundle</code> and <code>PropertyResourceBundle</code>,
177 * that provide a fairly simple way to create resources.
178 * As you saw briefly in a previous example, <code>ListResourceBundle</code>
179 * manages its resource as a list of key/value pairs.
180 * <code>PropertyResourceBundle</code> uses a properties file to manage
181 * its resources.
182 *
183 * <p>
184 * If <code>ListResourceBundle</code> or <code>PropertyResourceBundle</code>
185 * do not suit your needs, you can write your own <code>ResourceBundle</code>
186 * subclass.  Your subclasses must override two methods: <code>handleGetObject</code>
187 * and <code>getKeys()</code>.
188 *
189 * <h4>ResourceBundle.Control</h4>
190 *
191 * The {@link ResourceBundle.Control} class provides information necessary
192 * to perform the bundle loading process by the <code>getBundle</code>
193 * factory methods that take a <code>ResourceBundle.Control</code>
194 * instance. You can implement your own subclass in order to enable
195 * non-standard resource bundle formats, change the search strategy, or
196 * define caching parameters. Refer to the descriptions of the class and the
197 * {@link #getBundle(String, Locale, ClassLoader, Control) getBundle}
198 * factory method for details.
199 *
200 * <h4>Cache Management</h4>
201 *
202 * Resource bundle instances created by the <code>getBundle</code> factory
203 * methods are cached by default, and the factory methods return the same
204 * resource bundle instance multiple times if it has been
205 * cached. <code>getBundle</code> clients may clear the cache, manage the
206 * lifetime of cached resource bundle instances using time-to-live values,
207 * or specify not to cache resource bundle instances. Refer to the
208 * descriptions of the {@linkplain #getBundle(String, Locale, ClassLoader,
209 * Control) <code>getBundle</code> factory method}, {@link
210 * #clearCache(ClassLoader) clearCache}, {@link
211 * Control#getTimeToLive(String, Locale)
212 * ResourceBundle.Control.getTimeToLive}, and {@link
213 * Control#needsReload(String, Locale, String, ClassLoader, ResourceBundle,
214 * long) ResourceBundle.Control.needsReload} for details.
215 *
216 * <h4>Example</h4>
217 *
218 * The following is a very simple example of a <code>ResourceBundle</code>
219 * subclass, <code>MyResources</code>, that manages two resources (for a larger number of
220 * resources you would probably use a <code>Map</code>).
221 * Notice that you don't need to supply a value if
222 * a "parent-level" <code>ResourceBundle</code> handles the same
223 * key with the same value (as for the okKey below).
224 * <blockquote>
225 * <pre>
226 * // default (English language, United States)
227 * public class MyResources extends ResourceBundle {
228 *     public Object handleGetObject(String key) {
229 *         if (key.equals("okKey")) return "Ok";
230 *         if (key.equals("cancelKey")) return "Cancel";
231 *         return null;
232 *     }
233 *
234 *     public Enumeration&lt;String&gt; getKeys() {
235 *         return Collections.enumeration(keySet());
236 *     }
237 *
238 *     // Overrides handleKeySet() so that the getKeys() implementation
239 *     // can rely on the keySet() value.
240 *     protected Set&lt;String&gt; handleKeySet() {
241 *         return new HashSet&lt;String&gt;(Arrays.asList("okKey", "cancelKey"));
242 *     }
243 * }
244 *
245 * // German language
246 * public class MyResources_de extends MyResources {
247 *     public Object handleGetObject(String key) {
248 *         // don't need okKey, since parent level handles it.
249 *         if (key.equals("cancelKey")) return "Abbrechen";
250 *         return null;
251 *     }
252 *
253 *     protected Set&lt;String&gt; handleKeySet() {
254 *         return new HashSet&lt;String&gt;(Arrays.asList("cancelKey"));
255 *     }
256 * }
257 * </pre>
258 * </blockquote>
259 * You do not have to restrict yourself to using a single family of
260 * <code>ResourceBundle</code>s. For example, you could have a set of bundles for
261 * exception messages, <code>ExceptionResources</code>
262 * (<code>ExceptionResources_fr</code>, <code>ExceptionResources_de</code>, ...),
263 * and one for widgets, <code>WidgetResource</code> (<code>WidgetResources_fr</code>,
264 * <code>WidgetResources_de</code>, ...); breaking up the resources however you like.
265 *
266 * @see ListResourceBundle
267 * @see PropertyResourceBundle
268 * @see MissingResourceException
269 * @since JDK1.1
270 */
271public abstract class ResourceBundle {
272
273    /** initial size of the bundle cache */
274    private static final int INITIAL_CACHE_SIZE = 32;
275
276    /** constant indicating that no resource bundle exists */
277    private static final ResourceBundle NONEXISTENT_BUNDLE = new ResourceBundle() {
278            public Enumeration<String> getKeys() { return null; }
279            protected Object handleGetObject(String key) { return null; }
280            public String toString() { return "NONEXISTENT_BUNDLE"; }
281        };
282
283
284    /**
285     * The cache is a map from cache keys (with bundle base name, locale, and
286     * class loader) to either a resource bundle or NONEXISTENT_BUNDLE wrapped by a
287     * BundleReference.
288     *
289     * The cache is a ConcurrentMap, allowing the cache to be searched
290     * concurrently by multiple threads.  This will also allow the cache keys
291     * to be reclaimed along with the ClassLoaders they reference.
292     *
293     * This variable would be better named "cache", but we keep the old
294     * name for compatibility with some workarounds for bug 4212439.
295     */
296    private static final ConcurrentMap<CacheKey, BundleReference> cacheList
297        = new ConcurrentHashMap<>(INITIAL_CACHE_SIZE);
298
299    /**
300     * Queue for reference objects referring to class loaders or bundles.
301     */
302    private static final ReferenceQueue referenceQueue = new ReferenceQueue();
303
304    /**
305     * The parent bundle of this bundle.
306     * The parent bundle is searched by {@link #getObject getObject}
307     * when this bundle does not contain a particular resource.
308     */
309    protected ResourceBundle parent = null;
310
311    /**
312     * The locale for this bundle.
313     */
314    private Locale locale = null;
315
316    /**
317     * The base bundle name for this bundle.
318     */
319    private String name;
320
321    /**
322     * The flag indicating this bundle has expired in the cache.
323     */
324    private volatile boolean expired;
325
326    /**
327     * The back link to the cache key. null if this bundle isn't in
328     * the cache (yet) or has expired.
329     */
330    private volatile CacheKey cacheKey;
331
332    /**
333     * A Set of the keys contained only in this ResourceBundle.
334     */
335    private volatile Set<String> keySet;
336
337    /**
338     * Sole constructor.  (For invocation by subclass constructors, typically
339     * implicit.)
340     */
341    public ResourceBundle() {
342    }
343
344    /**
345     * Gets a string for the given key from this resource bundle or one of its parents.
346     * Calling this method is equivalent to calling
347     * <blockquote>
348     * <code>(String) {@link #getObject(java.lang.String) getObject}(key)</code>.
349     * </blockquote>
350     *
351     * @param key the key for the desired string
352     * @exception NullPointerException if <code>key</code> is <code>null</code>
353     * @exception MissingResourceException if no object for the given key can be found
354     * @exception ClassCastException if the object found for the given key is not a string
355     * @return the string for the given key
356     */
357    public final String getString(String key) {
358        return (String) getObject(key);
359    }
360
361    /**
362     * Gets a string array for the given key from this resource bundle or one of its parents.
363     * Calling this method is equivalent to calling
364     * <blockquote>
365     * <code>(String[]) {@link #getObject(java.lang.String) getObject}(key)</code>.
366     * </blockquote>
367     *
368     * @param key the key for the desired string array
369     * @exception NullPointerException if <code>key</code> is <code>null</code>
370     * @exception MissingResourceException if no object for the given key can be found
371     * @exception ClassCastException if the object found for the given key is not a string array
372     * @return the string array for the given key
373     */
374    public final String[] getStringArray(String key) {
375        return (String[]) getObject(key);
376    }
377
378    /**
379     * Gets an object for the given key from this resource bundle or one of its parents.
380     * This method first tries to obtain the object from this resource bundle using
381     * {@link #handleGetObject(java.lang.String) handleGetObject}.
382     * If not successful, and the parent resource bundle is not null,
383     * it calls the parent's <code>getObject</code> method.
384     * If still not successful, it throws a MissingResourceException.
385     *
386     * @param key the key for the desired object
387     * @exception NullPointerException if <code>key</code> is <code>null</code>
388     * @exception MissingResourceException if no object for the given key can be found
389     * @return the object for the given key
390     */
391    public final Object getObject(String key) {
392        Object obj = handleGetObject(key);
393        if (obj == null) {
394            if (parent != null) {
395                obj = parent.getObject(key);
396            }
397            if (obj == null)
398                throw new MissingResourceException("Can't find resource for bundle "
399                                                   +this.getClass().getName()
400                                                   +", key "+key,
401                                                   this.getClass().getName(),
402                                                   key);
403        }
404        return obj;
405    }
406
407    /**
408     * Returns the locale of this resource bundle. This method can be used after a
409     * call to getBundle() to determine whether the resource bundle returned really
410     * corresponds to the requested locale or is a fallback.
411     *
412     * @return the locale of this resource bundle
413     */
414    public Locale getLocale() {
415        return locale;
416    }
417
418    /*
419     * Automatic determination of the ClassLoader to be used to load
420     * resources on behalf of the client.
421     */
422    private static ClassLoader getLoader(ClassLoader cl) {
423        if (cl == null) {
424            // When the caller's loader is the boot class loader, cl is null
425            // here. In that case, ClassLoader.getSystemClassLoader() may
426            // return the same class loader that the application is
427            // using. We therefore use a wrapper ClassLoader to create a
428            // separate scope for bundles loaded on behalf of the Java
429            // runtime so that these bundles cannot be returned from the
430            // cache to the application (5048280).
431            cl = RBClassLoader.INSTANCE;
432        }
433        return cl;
434    }
435
436    /**
437     * A wrapper of ClassLoader.getSystemClassLoader().
438     */
439    private static class RBClassLoader extends ClassLoader {
440        private static final RBClassLoader INSTANCE = AccessController.doPrivileged(
441                    new PrivilegedAction<RBClassLoader>() {
442                        public RBClassLoader run() {
443                            return new RBClassLoader();
444                        }
445                    });
446        private static final ClassLoader loader = ClassLoader.getSystemClassLoader();
447
448        private RBClassLoader() {
449        }
450        public Class<?> loadClass(String name) throws ClassNotFoundException {
451            if (loader != null) {
452                return loader.loadClass(name);
453            }
454            return Class.forName(name);
455        }
456        public URL getResource(String name) {
457            if (loader != null) {
458                return loader.getResource(name);
459            }
460            return ClassLoader.getSystemResource(name);
461        }
462        public InputStream getResourceAsStream(String name) {
463            if (loader != null) {
464                return loader.getResourceAsStream(name);
465            }
466            return ClassLoader.getSystemResourceAsStream(name);
467        }
468    }
469
470    /**
471     * Sets the parent bundle of this bundle.
472     * The parent bundle is searched by {@link #getObject getObject}
473     * when this bundle does not contain a particular resource.
474     *
475     * @param parent this bundle's parent bundle.
476     */
477    protected void setParent(ResourceBundle parent) {
478        assert parent != NONEXISTENT_BUNDLE;
479        this.parent = parent;
480    }
481
482    /**
483     * Key used for cached resource bundles.  The key checks the base
484     * name, the locale, and the class loader to determine if the
485     * resource is a match to the requested one. The loader may be
486     * null, but the base name and the locale must have a non-null
487     * value.
488     */
489    private static final class CacheKey implements Cloneable {
490        // These three are the actual keys for lookup in Map.
491        private String name;
492        private Locale locale;
493        private LoaderReference loaderRef;
494
495        // bundle format which is necessary for calling
496        // Control.needsReload().
497        private String format;
498
499        // These time values are in CacheKey so that NONEXISTENT_BUNDLE
500        // doesn't need to be cloned for caching.
501
502        // The time when the bundle has been loaded
503        private volatile long loadTime;
504
505        // The time when the bundle expires in the cache, or either
506        // Control.TTL_DONT_CACHE or Control.TTL_NO_EXPIRATION_CONTROL.
507        private volatile long expirationTime;
508
509        // Placeholder for an error report by a Throwable
510        private Throwable cause;
511
512        // Hash code value cache to avoid recalculating the hash code
513        // of this instance.
514        private int hashCodeCache;
515
516        CacheKey(String baseName, Locale locale, ClassLoader loader) {
517            this.name = baseName;
518            this.locale = locale;
519            if (loader == null) {
520                this.loaderRef = null;
521            } else {
522                loaderRef = new LoaderReference(loader, referenceQueue, this);
523            }
524            calculateHashCode();
525        }
526
527        String getName() {
528            return name;
529        }
530
531        CacheKey setName(String baseName) {
532            if (!this.name.equals(baseName)) {
533                this.name = baseName;
534                calculateHashCode();
535            }
536            return this;
537        }
538
539        Locale getLocale() {
540            return locale;
541        }
542
543        CacheKey setLocale(Locale locale) {
544            if (!this.locale.equals(locale)) {
545                this.locale = locale;
546                calculateHashCode();
547            }
548            return this;
549        }
550
551        ClassLoader getLoader() {
552            return (loaderRef != null) ? loaderRef.get() : null;
553        }
554
555        public boolean equals(Object other) {
556            if (this == other) {
557                return true;
558            }
559            try {
560                final CacheKey otherEntry = (CacheKey)other;
561                //quick check to see if they are not equal
562                if (hashCodeCache != otherEntry.hashCodeCache) {
563                    return false;
564                }
565                //are the names the same?
566                if (!name.equals(otherEntry.name)) {
567                    return false;
568                }
569                // are the locales the same?
570                if (!locale.equals(otherEntry.locale)) {
571                    return false;
572                }
573                //are refs (both non-null) or (both null)?
574                if (loaderRef == null) {
575                    return otherEntry.loaderRef == null;
576                }
577                ClassLoader loader = loaderRef.get();
578                return (otherEntry.loaderRef != null)
579                        // with a null reference we can no longer find
580                        // out which class loader was referenced; so
581                        // treat it as unequal
582                        && (loader != null)
583                        && (loader == otherEntry.loaderRef.get());
584            } catch (NullPointerException e) {
585            } catch (ClassCastException e) {
586            }
587            return false;
588        }
589
590        public int hashCode() {
591            return hashCodeCache;
592        }
593
594        private void calculateHashCode() {
595            hashCodeCache = name.hashCode() << 3;
596            hashCodeCache ^= locale.hashCode();
597            ClassLoader loader = getLoader();
598            if (loader != null) {
599                hashCodeCache ^= loader.hashCode();
600            }
601        }
602
603        public Object clone() {
604            try {
605                CacheKey clone = (CacheKey) super.clone();
606                if (loaderRef != null) {
607                    clone.loaderRef = new LoaderReference(loaderRef.get(),
608                                                          referenceQueue, clone);
609                }
610                // Clear the reference to a Throwable
611                clone.cause = null;
612                return clone;
613            } catch (CloneNotSupportedException e) {
614                //this should never happen
615                throw new InternalError();
616            }
617        }
618
619        String getFormat() {
620            return format;
621        }
622
623        void setFormat(String format) {
624            this.format = format;
625        }
626
627        private void setCause(Throwable cause) {
628            if (this.cause == null) {
629                this.cause = cause;
630            } else {
631                // Override the cause if the previous one is
632                // ClassNotFoundException.
633                if (this.cause instanceof ClassNotFoundException) {
634                    this.cause = cause;
635                }
636            }
637        }
638
639        private Throwable getCause() {
640            return cause;
641        }
642
643        public String toString() {
644            String l = locale.toString();
645            if (l.length() == 0) {
646                if (locale.getVariant().length() != 0) {
647                    l = "__" + locale.getVariant();
648                } else {
649                    l = "\"\"";
650                }
651            }
652            return "CacheKey[" + name + ", lc=" + l + ", ldr=" + getLoader()
653                + "(format=" + format + ")]";
654        }
655    }
656
657    /**
658     * The common interface to get a CacheKey in LoaderReference and
659     * BundleReference.
660     */
661    private static interface CacheKeyReference {
662        public CacheKey getCacheKey();
663    }
664
665    /**
666     * References to class loaders are weak references, so that they can be
667     * garbage collected when nobody else is using them. The ResourceBundle
668     * class has no reason to keep class loaders alive.
669     */
670    private static final class LoaderReference extends WeakReference<ClassLoader>
671                                               implements CacheKeyReference {
672        private CacheKey cacheKey;
673
674        LoaderReference(ClassLoader referent, ReferenceQueue q, CacheKey key) {
675            super(referent, q);
676            cacheKey = key;
677        }
678
679        public CacheKey getCacheKey() {
680            return cacheKey;
681        }
682    }
683
684    /**
685     * References to bundles are soft references so that they can be garbage
686     * collected when they have no hard references.
687     */
688    private static final class BundleReference extends SoftReference<ResourceBundle>
689                                               implements CacheKeyReference {
690        private CacheKey cacheKey;
691
692        BundleReference(ResourceBundle referent, ReferenceQueue q, CacheKey key) {
693            super(referent, q);
694            cacheKey = key;
695        }
696
697        public CacheKey getCacheKey() {
698            return cacheKey;
699        }
700    }
701
702    /**
703     * Gets a resource bundle using the specified base name, the default locale,
704     * and the caller's class loader. Calling this method is equivalent to calling
705     * <blockquote>
706     * <code>getBundle(baseName, Locale.getDefault(), this.getClass().getClassLoader())</code>,
707     * </blockquote>
708     * except that <code>getClassLoader()</code> is run with the security
709     * privileges of <code>ResourceBundle</code>.
710     * See {@link #getBundle(String, Locale, ClassLoader) getBundle}
711     * for a complete description of the search and instantiation strategy.
712     *
713     * @param baseName the base name of the resource bundle, a fully qualified class name
714     * @exception java.lang.NullPointerException
715     *     if <code>baseName</code> is <code>null</code>
716     * @exception MissingResourceException
717     *     if no resource bundle for the specified base name can be found
718     * @return a resource bundle for the given base name and the default locale
719     */
720    @CallerSensitive
721    public static final ResourceBundle getBundle(String baseName)
722    {
723        return getBundleImpl(baseName, Locale.getDefault(),
724                             /* must determine loader here, else we break stack invariant */
725                             getLoader(VMStack.getCallingClassLoader()),
726                             Control.INSTANCE);
727    }
728
729    /**
730     * Returns a resource bundle using the specified base name, the
731     * default locale and the specified control. Calling this method
732     * is equivalent to calling
733     * <pre>
734     * getBundle(baseName, Locale.getDefault(),
735     *           this.getClass().getClassLoader(), control),
736     * </pre>
737     * except that <code>getClassLoader()</code> is run with the security
738     * privileges of <code>ResourceBundle</code>.  See {@link
739     * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
740     * complete description of the resource bundle loading process with a
741     * <code>ResourceBundle.Control</code>.
742     *
743     * @param baseName
744     *        the base name of the resource bundle, a fully qualified class
745     *        name
746     * @param control
747     *        the control which gives information for the resource bundle
748     *        loading process
749     * @return a resource bundle for the given base name and the default
750     *        locale
751     * @exception NullPointerException
752     *        if <code>baseName</code> or <code>control</code> is
753     *        <code>null</code>
754     * @exception MissingResourceException
755     *        if no resource bundle for the specified base name can be found
756     * @exception IllegalArgumentException
757     *        if the given <code>control</code> doesn't perform properly
758     *        (e.g., <code>control.getCandidateLocales</code> returns null.)
759     *        Note that validation of <code>control</code> is performed as
760     *        needed.
761     * @since 1.6
762     */
763    @CallerSensitive
764    public static final ResourceBundle getBundle(String baseName,
765                                                 Control control) {
766        return getBundleImpl(baseName, Locale.getDefault(),
767                             /* must determine loader here, else we break stack invariant */
768                             getLoader(VMStack.getCallingClassLoader()),
769                             control);
770    }
771
772    /**
773     * Gets a resource bundle using the specified base name and locale,
774     * and the caller's class loader. Calling this method is equivalent to calling
775     * <blockquote>
776     * <code>getBundle(baseName, locale, this.getClass().getClassLoader())</code>,
777     * </blockquote>
778     * except that <code>getClassLoader()</code> is run with the security
779     * privileges of <code>ResourceBundle</code>.
780     * See {@link #getBundle(String, Locale, ClassLoader) getBundle}
781     * for a complete description of the search and instantiation strategy.
782     *
783     * @param baseName
784     *        the base name of the resource bundle, a fully qualified class name
785     * @param locale
786     *        the locale for which a resource bundle is desired
787     * @exception NullPointerException
788     *        if <code>baseName</code> or <code>locale</code> is <code>null</code>
789     * @exception MissingResourceException
790     *        if no resource bundle for the specified base name can be found
791     * @return a resource bundle for the given base name and locale
792     */
793    @CallerSensitive
794    public static final ResourceBundle getBundle(String baseName,
795                                                 Locale locale)
796    {
797        return getBundleImpl(baseName, locale,
798                             /* must determine loader here, else we break stack invariant */
799                             getLoader(VMStack.getCallingClassLoader()),
800                             Control.INSTANCE);
801    }
802
803    /**
804     * Returns a resource bundle using the specified base name, target
805     * locale and control, and the caller's class loader. Calling this
806     * method is equivalent to calling
807     * <pre>
808     * getBundle(baseName, targetLocale, this.getClass().getClassLoader(),
809     *           control),
810     * </pre>
811     * except that <code>getClassLoader()</code> is run with the security
812     * privileges of <code>ResourceBundle</code>.  See {@link
813     * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
814     * complete description of the resource bundle loading process with a
815     * <code>ResourceBundle.Control</code>.
816     *
817     * @param baseName
818     *        the base name of the resource bundle, a fully qualified
819     *        class name
820     * @param targetLocale
821     *        the locale for which a resource bundle is desired
822     * @param control
823     *        the control which gives information for the resource
824     *        bundle loading process
825     * @return a resource bundle for the given base name and a
826     *        <code>Locale</code> in <code>locales</code>
827     * @exception NullPointerException
828     *        if <code>baseName</code>, <code>locales</code> or
829     *        <code>control</code> is <code>null</code>
830     * @exception MissingResourceException
831     *        if no resource bundle for the specified base name in any
832     *        of the <code>locales</code> can be found.
833     * @exception IllegalArgumentException
834     *        if the given <code>control</code> doesn't perform properly
835     *        (e.g., <code>control.getCandidateLocales</code> returns null.)
836     *        Note that validation of <code>control</code> is performed as
837     *        needed.
838     * @since 1.6
839     */
840    @CallerSensitive
841    public static final ResourceBundle getBundle(String baseName, Locale targetLocale,
842                                                 Control control) {
843        return getBundleImpl(baseName, targetLocale,
844                             /* must determine loader here, else we break stack invariant */
845                             getLoader(VMStack.getCallingClassLoader()),
846                             control);
847    }
848
849    /**
850     * Gets a resource bundle using the specified base name, locale, and class
851     * loader.
852     *
853     * <p><a name="default_behavior"></a>This method behaves the same as calling
854     * {@link #getBundle(String, Locale, ClassLoader, Control)} passing a
855     * default instance of {@link Control}. The following describes this behavior.
856     *
857     * <p><code>getBundle</code> uses the base name, the specified locale, and
858     * the default locale (obtained from {@link java.util.Locale#getDefault()
859     * Locale.getDefault}) to generate a sequence of <a
860     * name="candidates"><em>candidate bundle names</em></a>.  If the specified
861     * locale's language, script, country, and variant are all empty strings,
862     * then the base name is the only candidate bundle name.  Otherwise, a list
863     * of candidate locales is generated from the attribute values of the
864     * specified locale (language, script, country and variant) and appended to
865     * the base name.  Typically, this will look like the following:
866     *
867     * <pre>
868     *     baseName + "_" + language + "_" + script + "_" + country + "_" + variant
869     *     baseName + "_" + language + "_" + script + "_" + country
870     *     baseName + "_" + language + "_" + script
871     *     baseName + "_" + language + "_" + country + "_" + variant
872     *     baseName + "_" + language + "_" + country
873     *     baseName + "_" + language
874     * </pre>
875     *
876     * <p>Candidate bundle names where the final component is an empty string
877     * are omitted, along with the underscore.  For example, if country is an
878     * empty string, the second and the fifth candidate bundle names above
879     * would be omitted.  Also, if script is an empty string, the candidate names
880     * including script are omitted.  For example, a locale with language "de"
881     * and variant "JAVA" will produce candidate names with base name
882     * "MyResource" below.
883     *
884     * <pre>
885     *     MyResource_de__JAVA
886     *     MyResource_de
887     * </pre>
888     *
889     * In the case that the variant contains one or more underscores ('_'), a
890     * sequence of bundle names generated by truncating the last underscore and
891     * the part following it is inserted after a candidate bundle name with the
892     * original variant.  For example, for a locale with language "en", script
893     * "Latn, country "US" and variant "WINDOWS_VISTA", and bundle base name
894     * "MyResource", the list of candidate bundle names below is generated:
895     *
896     * <pre>
897     * MyResource_en_Latn_US_WINDOWS_VISTA
898     * MyResource_en_Latn_US_WINDOWS
899     * MyResource_en_Latn_US
900     * MyResource_en_Latn
901     * MyResource_en_US_WINDOWS_VISTA
902     * MyResource_en_US_WINDOWS
903     * MyResource_en_US
904     * MyResource_en
905     * </pre>
906     *
907     * <blockquote><b>Note:</b> For some <code>Locale</code>s, the list of
908     * candidate bundle names contains extra names, or the order of bundle names
909     * is slightly modified.  See the description of the default implementation
910     * of {@link Control#getCandidateLocales(String, Locale)
911     * getCandidateLocales} for details.</blockquote>
912     *
913     * <p><code>getBundle</code> then iterates over the candidate bundle names
914     * to find the first one for which it can <em>instantiate</em> an actual
915     * resource bundle. It uses the default controls' {@link Control#getFormats
916     * getFormats} method, which generates two bundle names for each generated
917     * name, the first a class name and the second a properties file name. For
918     * each candidate bundle name, it attempts to create a resource bundle:
919     *
920     * <ul><li>First, it attempts to load a class using the generated class name.
921     * If such a class can be found and loaded using the specified class
922     * loader, is assignment compatible with ResourceBundle, is accessible from
923     * ResourceBundle, and can be instantiated, <code>getBundle</code> creates a
924     * new instance of this class and uses it as the <em>result resource
925     * bundle</em>.
926     *
927     * <li>Otherwise, <code>getBundle</code> attempts to locate a property
928     * resource file using the generated properties file name.  It generates a
929     * path name from the candidate bundle name by replacing all "." characters
930     * with "/" and appending the string ".properties".  It attempts to find a
931     * "resource" with this name using {@link
932     * java.lang.ClassLoader#getResource(java.lang.String)
933     * ClassLoader.getResource}.  (Note that a "resource" in the sense of
934     * <code>getResource</code> has nothing to do with the contents of a
935     * resource bundle, it is just a container of data, such as a file.)  If it
936     * finds a "resource", it attempts to create a new {@link
937     * PropertyResourceBundle} instance from its contents.  If successful, this
938     * instance becomes the <em>result resource bundle</em>.  </ul>
939     *
940     * <p>This continues until a result resource bundle is instantiated or the
941     * list of candidate bundle names is exhausted.  If no matching resource
942     * bundle is found, the default control's {@link Control#getFallbackLocale
943     * getFallbackLocale} method is called, which returns the current default
944     * locale.  A new sequence of candidate locale names is generated using this
945     * locale and and searched again, as above.
946     *
947     * <p>If still no result bundle is found, the base name alone is looked up. If
948     * this still fails, a <code>MissingResourceException</code> is thrown.
949     *
950     * <p><a name="parent_chain"></a> Once a result resource bundle has been found,
951     * its <em>parent chain</em> is instantiated.  If the result bundle already
952     * has a parent (perhaps because it was returned from a cache) the chain is
953     * complete.
954     *
955     * <p>Otherwise, <code>getBundle</code> examines the remainder of the
956     * candidate locale list that was used during the pass that generated the
957     * result resource bundle.  (As before, candidate bundle names where the
958     * final component is an empty string are omitted.)  When it comes to the
959     * end of the candidate list, it tries the plain bundle name.  With each of the
960     * candidate bundle names it attempts to instantiate a resource bundle (first
961     * looking for a class and then a properties file, as described above).
962     *
963     * <p>Whenever it succeeds, it calls the previously instantiated resource
964     * bundle's {@link #setParent(java.util.ResourceBundle) setParent} method
965     * with the new resource bundle.  This continues until the list of names
966     * is exhausted or the current bundle already has a non-null parent.
967     *
968     * <p>Once the parent chain is complete, the bundle is returned.
969     *
970     * <p><b>Note:</b> <code>getBundle</code> caches instantiated resource
971     * bundles and might return the same resource bundle instance multiple times.
972     *
973     * <p><b>Note:</b>The <code>baseName</code> argument should be a fully
974     * qualified class name. However, for compatibility with earlier versions,
975     * Sun's Java SE Runtime Environments do not verify this, and so it is
976     * possible to access <code>PropertyResourceBundle</code>s by specifying a
977     * path name (using "/") instead of a fully qualified class name (using
978     * ".").
979     *
980     * <p><a name="default_behavior_example"></a>
981     * <strong>Example:</strong>
982     * <p>
983     * The following class and property files are provided:
984     * <pre>
985     *     MyResources.class
986     *     MyResources.properties
987     *     MyResources_fr.properties
988     *     MyResources_fr_CH.class
989     *     MyResources_fr_CH.properties
990     *     MyResources_en.properties
991     *     MyResources_es_ES.class
992     * </pre>
993     *
994     * The contents of all files are valid (that is, public non-abstract
995     * subclasses of <code>ResourceBundle</code> for the ".class" files,
996     * syntactically correct ".properties" files).  The default locale is
997     * <code>Locale("en", "GB")</code>.
998     *
999     * <p>Calling <code>getBundle</code> with the locale arguments below will
1000     * instantiate resource bundles as follows:
1001     *
1002     * <table>
1003     * <tr><td>Locale("fr", "CH")</td><td>MyResources_fr_CH.class, parent MyResources_fr.properties, parent MyResources.class</td></tr>
1004     * <tr><td>Locale("fr", "FR")</td><td>MyResources_fr.properties, parent MyResources.class</td></tr>
1005     * <tr><td>Locale("de", "DE")</td><td>MyResources_en.properties, parent MyResources.class</td></tr>
1006     * <tr><td>Locale("en", "US")</td><td>MyResources_en.properties, parent MyResources.class</td></tr>
1007     * <tr><td>Locale("es", "ES")</td><td>MyResources_es_ES.class, parent MyResources.class</td></tr>
1008     * </table>
1009     *
1010     * <p>The file MyResources_fr_CH.properties is never used because it is
1011     * hidden by the MyResources_fr_CH.class. Likewise, MyResources.properties
1012     * is also hidden by MyResources.class.
1013     *
1014     * @param baseName the base name of the resource bundle, a fully qualified class name
1015     * @param locale the locale for which a resource bundle is desired
1016     * @param loader the class loader from which to load the resource bundle
1017     * @return a resource bundle for the given base name and locale
1018     * @exception java.lang.NullPointerException
1019     *        if <code>baseName</code>, <code>locale</code>, or <code>loader</code> is <code>null</code>
1020     * @exception MissingResourceException
1021     *        if no resource bundle for the specified base name can be found
1022     * @since 1.2
1023     */
1024    public static ResourceBundle getBundle(String baseName, Locale locale,
1025                                           ClassLoader loader)
1026    {
1027        if (loader == null) {
1028            throw new NullPointerException();
1029        }
1030        return getBundleImpl(baseName, locale, loader, Control.INSTANCE);
1031    }
1032
1033    /**
1034     * Returns a resource bundle using the specified base name, target
1035     * locale, class loader and control. Unlike the {@linkplain
1036     * #getBundle(String, Locale, ClassLoader) <code>getBundle</code>
1037     * factory methods with no <code>control</code> argument}, the given
1038     * <code>control</code> specifies how to locate and instantiate resource
1039     * bundles. Conceptually, the bundle loading process with the given
1040     * <code>control</code> is performed in the following steps.
1041     *
1042     * <p>
1043     * <ol>
1044     * <li>This factory method looks up the resource bundle in the cache for
1045     * the specified <code>baseName</code>, <code>targetLocale</code> and
1046     * <code>loader</code>.  If the requested resource bundle instance is
1047     * found in the cache and the time-to-live periods of the instance and
1048     * all of its parent instances have not expired, the instance is returned
1049     * to the caller. Otherwise, this factory method proceeds with the
1050     * loading process below.</li>
1051     *
1052     * <li>The {@link ResourceBundle.Control#getFormats(String)
1053     * control.getFormats} method is called to get resource bundle formats
1054     * to produce bundle or resource names. The strings
1055     * <code>"java.class"</code> and <code>"java.properties"</code>
1056     * designate class-based and {@linkplain PropertyResourceBundle
1057     * property}-based resource bundles, respectively. Other strings
1058     * starting with <code>"java."</code> are reserved for future extensions
1059     * and must not be used for application-defined formats. Other strings
1060     * designate application-defined formats.</li>
1061     *
1062     * <li>The {@link ResourceBundle.Control#getCandidateLocales(String,
1063     * Locale) control.getCandidateLocales} method is called with the target
1064     * locale to get a list of <em>candidate <code>Locale</code>s</em> for
1065     * which resource bundles are searched.</li>
1066     *
1067     * <li>The {@link ResourceBundle.Control#newBundle(String, Locale,
1068     * String, ClassLoader, boolean) control.newBundle} method is called to
1069     * instantiate a <code>ResourceBundle</code> for the base bundle name, a
1070     * candidate locale, and a format. (Refer to the note on the cache
1071     * lookup below.) This step is iterated over all combinations of the
1072     * candidate locales and formats until the <code>newBundle</code> method
1073     * returns a <code>ResourceBundle</code> instance or the iteration has
1074     * used up all the combinations. For example, if the candidate locales
1075     * are <code>Locale("de", "DE")</code>, <code>Locale("de")</code> and
1076     * <code>Locale("")</code> and the formats are <code>"java.class"</code>
1077     * and <code>"java.properties"</code>, then the following is the
1078     * sequence of locale-format combinations to be used to call
1079     * <code>control.newBundle</code>.
1080     *
1081     * <table style="width: 50%; text-align: left; margin-left: 40px;"
1082     *  border="0" cellpadding="2" cellspacing="2">
1083     * <tbody><code>
1084     * <tr>
1085     * <td
1086     * style="vertical-align: top; text-align: left; font-weight: bold; width: 50%;">Locale<br>
1087     * </td>
1088     * <td
1089     * style="vertical-align: top; text-align: left; font-weight: bold; width: 50%;">format<br>
1090     * </td>
1091     * </tr>
1092     * <tr>
1093     * <td style="vertical-align: top; width: 50%;">Locale("de", "DE")<br>
1094     * </td>
1095     * <td style="vertical-align: top; width: 50%;">java.class<br>
1096     * </td>
1097     * </tr>
1098     * <tr>
1099     * <td style="vertical-align: top; width: 50%;">Locale("de", "DE")</td>
1100     * <td style="vertical-align: top; width: 50%;">java.properties<br>
1101     * </td>
1102     * </tr>
1103     * <tr>
1104     * <td style="vertical-align: top; width: 50%;">Locale("de")</td>
1105     * <td style="vertical-align: top; width: 50%;">java.class</td>
1106     * </tr>
1107     * <tr>
1108     * <td style="vertical-align: top; width: 50%;">Locale("de")</td>
1109     * <td style="vertical-align: top; width: 50%;">java.properties</td>
1110     * </tr>
1111     * <tr>
1112     * <td style="vertical-align: top; width: 50%;">Locale("")<br>
1113     * </td>
1114     * <td style="vertical-align: top; width: 50%;">java.class</td>
1115     * </tr>
1116     * <tr>
1117     * <td style="vertical-align: top; width: 50%;">Locale("")</td>
1118     * <td style="vertical-align: top; width: 50%;">java.properties</td>
1119     * </tr>
1120     * </code></tbody>
1121     * </table>
1122     * </li>
1123     *
1124     * <li>If the previous step has found no resource bundle, proceed to
1125     * Step 6. If a bundle has been found that is a base bundle (a bundle
1126     * for <code>Locale("")</code>), and the candidate locale list only contained
1127     * <code>Locale("")</code>, return the bundle to the caller. If a bundle
1128     * has been found that is a base bundle, but the candidate locale list
1129     * contained locales other than Locale(""), put the bundle on hold and
1130     * proceed to Step 6. If a bundle has been found that is not a base
1131     * bundle, proceed to Step 7.</li>
1132     *
1133     * <li>The {@link ResourceBundle.Control#getFallbackLocale(String,
1134     * Locale) control.getFallbackLocale} method is called to get a fallback
1135     * locale (alternative to the current target locale) to try further
1136     * finding a resource bundle. If the method returns a non-null locale,
1137     * it becomes the next target locale and the loading process starts over
1138     * from Step 3. Otherwise, if a base bundle was found and put on hold in
1139     * a previous Step 5, it is returned to the caller now. Otherwise, a
1140     * MissingResourceException is thrown.</li>
1141     *
1142     * <li>At this point, we have found a resource bundle that's not the
1143     * base bundle. If this bundle set its parent during its instantiation,
1144     * it is returned to the caller. Otherwise, its <a
1145     * href="./ResourceBundle.html#parent_chain">parent chain</a> is
1146     * instantiated based on the list of candidate locales from which it was
1147     * found. Finally, the bundle is returned to the caller.</li>
1148     * </ol>
1149     *
1150     * <p>During the resource bundle loading process above, this factory
1151     * method looks up the cache before calling the {@link
1152     * Control#newBundle(String, Locale, String, ClassLoader, boolean)
1153     * control.newBundle} method.  If the time-to-live period of the
1154     * resource bundle found in the cache has expired, the factory method
1155     * calls the {@link ResourceBundle.Control#needsReload(String, Locale,
1156     * String, ClassLoader, ResourceBundle, long) control.needsReload}
1157     * method to determine whether the resource bundle needs to be reloaded.
1158     * If reloading is required, the factory method calls
1159     * <code>control.newBundle</code> to reload the resource bundle.  If
1160     * <code>control.newBundle</code> returns <code>null</code>, the factory
1161     * method puts a dummy resource bundle in the cache as a mark of
1162     * nonexistent resource bundles in order to avoid lookup overhead for
1163     * subsequent requests. Such dummy resource bundles are under the same
1164     * expiration control as specified by <code>control</code>.
1165     *
1166     * <p>All resource bundles loaded are cached by default. Refer to
1167     * {@link Control#getTimeToLive(String,Locale)
1168     * control.getTimeToLive} for details.
1169     *
1170     * <p>The following is an example of the bundle loading process with the
1171     * default <code>ResourceBundle.Control</code> implementation.
1172     *
1173     * <p>Conditions:
1174     * <ul>
1175     * <li>Base bundle name: <code>foo.bar.Messages</code>
1176     * <li>Requested <code>Locale</code>: {@link Locale#ITALY}</li>
1177     * <li>Default <code>Locale</code>: {@link Locale#FRENCH}</li>
1178     * <li>Available resource bundles:
1179     * <code>foo/bar/Messages_fr.properties</code> and
1180     * <code>foo/bar/Messages.properties</code></li>
1181     * </ul>
1182     *
1183     * <p>First, <code>getBundle</code> tries loading a resource bundle in
1184     * the following sequence.
1185     *
1186     * <ul>
1187     * <li>class <code>foo.bar.Messages_it_IT</code>
1188     * <li>file <code>foo/bar/Messages_it_IT.properties</code>
1189     * <li>class <code>foo.bar.Messages_it</code></li>
1190     * <li>file <code>foo/bar/Messages_it.properties</code></li>
1191     * <li>class <code>foo.bar.Messages</code></li>
1192     * <li>file <code>foo/bar/Messages.properties</code></li>
1193     * </ul>
1194     *
1195     * <p>At this point, <code>getBundle</code> finds
1196     * <code>foo/bar/Messages.properties</code>, which is put on hold
1197     * because it's the base bundle.  <code>getBundle</code> calls {@link
1198     * Control#getFallbackLocale(String, Locale)
1199     * control.getFallbackLocale("foo.bar.Messages", Locale.ITALY)} which
1200     * returns <code>Locale.FRENCH</code>. Next, <code>getBundle</code>
1201     * tries loading a bundle in the following sequence.
1202     *
1203     * <ul>
1204     * <li>class <code>foo.bar.Messages_fr</code></li>
1205     * <li>file <code>foo/bar/Messages_fr.properties</code></li>
1206     * <li>class <code>foo.bar.Messages</code></li>
1207     * <li>file <code>foo/bar/Messages.properties</code></li>
1208     * </ul>
1209     *
1210     * <p><code>getBundle</code> finds
1211     * <code>foo/bar/Messages_fr.properties</code> and creates a
1212     * <code>ResourceBundle</code> instance. Then, <code>getBundle</code>
1213     * sets up its parent chain from the list of the candiate locales.  Only
1214     * <code>foo/bar/Messages.properties</code> is found in the list and
1215     * <code>getBundle</code> creates a <code>ResourceBundle</code> instance
1216     * that becomes the parent of the instance for
1217     * <code>foo/bar/Messages_fr.properties</code>.
1218     *
1219     * @param baseName
1220     *        the base name of the resource bundle, a fully qualified
1221     *        class name
1222     * @param targetLocale
1223     *        the locale for which a resource bundle is desired
1224     * @param loader
1225     *        the class loader from which to load the resource bundle
1226     * @param control
1227     *        the control which gives information for the resource
1228     *        bundle loading process
1229     * @return a resource bundle for the given base name and locale
1230     * @exception NullPointerException
1231     *        if <code>baseName</code>, <code>targetLocale</code>,
1232     *        <code>loader</code>, or <code>control</code> is
1233     *        <code>null</code>
1234     * @exception MissingResourceException
1235     *        if no resource bundle for the specified base name can be found
1236     * @exception IllegalArgumentException
1237     *        if the given <code>control</code> doesn't perform properly
1238     *        (e.g., <code>control.getCandidateLocales</code> returns null.)
1239     *        Note that validation of <code>control</code> is performed as
1240     *        needed.
1241     * @since 1.6
1242     */
1243    public static ResourceBundle getBundle(String baseName, Locale targetLocale,
1244                                           ClassLoader loader, Control control) {
1245        if (loader == null || control == null) {
1246            throw new NullPointerException();
1247        }
1248        return getBundleImpl(baseName, targetLocale, loader, control);
1249    }
1250
1251    private static ResourceBundle getBundleImpl(String baseName, Locale locale,
1252                                                ClassLoader loader, Control control) {
1253        if (locale == null || control == null) {
1254            throw new NullPointerException();
1255        }
1256
1257        // We create a CacheKey here for use by this call. The base
1258        // name and loader will never change during the bundle loading
1259        // process. We have to make sure that the locale is set before
1260        // using it as a cache key.
1261        CacheKey cacheKey = new CacheKey(baseName, locale, loader);
1262        ResourceBundle bundle = null;
1263
1264        // Quick lookup of the cache.
1265        BundleReference bundleRef = cacheList.get(cacheKey);
1266        if (bundleRef != null) {
1267            bundle = bundleRef.get();
1268            bundleRef = null;
1269        }
1270
1271        // If this bundle and all of its parents are valid (not expired),
1272        // then return this bundle. If any of the bundles is expired, we
1273        // don't call control.needsReload here but instead drop into the
1274        // complete loading process below.
1275        if (isValidBundle(bundle) && hasValidParentChain(bundle)) {
1276            return bundle;
1277        }
1278
1279        // No valid bundle was found in the cache, so we need to load the
1280        // resource bundle and its parents.
1281
1282        boolean isKnownControl = (control == Control.INSTANCE) ||
1283                                   (control instanceof SingleFormatControl);
1284        List<String> formats = control.getFormats(baseName);
1285        if (!isKnownControl && !checkList(formats)) {
1286            throw new IllegalArgumentException("Invalid Control: getFormats");
1287        }
1288
1289        ResourceBundle baseBundle = null;
1290        for (Locale targetLocale = locale;
1291             targetLocale != null;
1292             targetLocale = control.getFallbackLocale(baseName, targetLocale)) {
1293            List<Locale> candidateLocales = control.getCandidateLocales(baseName, targetLocale);
1294            if (!isKnownControl && !checkList(candidateLocales)) {
1295                throw new IllegalArgumentException("Invalid Control: getCandidateLocales");
1296            }
1297
1298            bundle = findBundle(cacheKey, candidateLocales, formats, 0, control, baseBundle);
1299
1300            // If the loaded bundle is the base bundle and exactly for the
1301            // requested locale or the only candidate locale, then take the
1302            // bundle as the resulting one. If the loaded bundle is the base
1303            // bundle, it's put on hold until we finish processing all
1304            // fallback locales.
1305            if (isValidBundle(bundle)) {
1306                boolean isBaseBundle = Locale.ROOT.equals(bundle.locale);
1307                if (!isBaseBundle || bundle.locale.equals(locale)
1308                    || (candidateLocales.size() == 1
1309                        && bundle.locale.equals(candidateLocales.get(0)))) {
1310                    break;
1311                }
1312
1313                // If the base bundle has been loaded, keep the reference in
1314                // baseBundle so that we can avoid any redundant loading in case
1315                // the control specify not to cache bundles.
1316                if (isBaseBundle && baseBundle == null) {
1317                    baseBundle = bundle;
1318                }
1319            }
1320        }
1321
1322        if (bundle == null) {
1323            if (baseBundle == null) {
1324                throwMissingResourceException(baseName, locale, cacheKey.getCause());
1325            }
1326            bundle = baseBundle;
1327        }
1328
1329        return bundle;
1330    }
1331
1332    /**
1333     * Checks if the given <code>List</code> is not null, not empty,
1334     * not having null in its elements.
1335     */
1336    private static final boolean checkList(List a) {
1337        boolean valid = (a != null && a.size() != 0);
1338        if (valid) {
1339            int size = a.size();
1340            for (int i = 0; valid && i < size; i++) {
1341                valid = (a.get(i) != null);
1342            }
1343        }
1344        return valid;
1345    }
1346
1347    private static final ResourceBundle findBundle(CacheKey cacheKey,
1348                                                   List<Locale> candidateLocales,
1349                                                   List<String> formats,
1350                                                   int index,
1351                                                   Control control,
1352                                                   ResourceBundle baseBundle) {
1353        Locale targetLocale = candidateLocales.get(index);
1354        ResourceBundle parent = null;
1355        if (index != candidateLocales.size() - 1) {
1356            parent = findBundle(cacheKey, candidateLocales, formats, index + 1,
1357                                control, baseBundle);
1358        } else if (baseBundle != null && Locale.ROOT.equals(targetLocale)) {
1359            return baseBundle;
1360        }
1361
1362        // Before we do the real loading work, see whether we need to
1363        // do some housekeeping: If references to class loaders or
1364        // resource bundles have been nulled out, remove all related
1365        // information from the cache.
1366        Object ref;
1367        while ((ref = referenceQueue.poll()) != null) {
1368            cacheList.remove(((CacheKeyReference)ref).getCacheKey());
1369        }
1370
1371        // flag indicating the resource bundle has expired in the cache
1372        boolean expiredBundle = false;
1373
1374        // First, look up the cache to see if it's in the cache, without
1375        // attempting to load bundle.
1376        cacheKey.setLocale(targetLocale);
1377        ResourceBundle bundle = findBundleInCache(cacheKey, control);
1378        if (isValidBundle(bundle)) {
1379            expiredBundle = bundle.expired;
1380            if (!expiredBundle) {
1381                // If its parent is the one asked for by the candidate
1382                // locales (the runtime lookup path), we can take the cached
1383                // one. (If it's not identical, then we'd have to check the
1384                // parent's parents to be consistent with what's been
1385                // requested.)
1386                if (bundle.parent == parent) {
1387                    return bundle;
1388                }
1389                // Otherwise, remove the cached one since we can't keep
1390                // the same bundles having different parents.
1391                BundleReference bundleRef = cacheList.get(cacheKey);
1392                if (bundleRef != null && bundleRef.get() == bundle) {
1393                    cacheList.remove(cacheKey, bundleRef);
1394                }
1395            }
1396        }
1397
1398        if (bundle != NONEXISTENT_BUNDLE) {
1399            CacheKey constKey = (CacheKey) cacheKey.clone();
1400
1401            try {
1402                bundle = loadBundle(cacheKey, formats, control, expiredBundle);
1403                if (bundle != null) {
1404                    if (bundle.parent == null) {
1405                        bundle.setParent(parent);
1406                    }
1407                    bundle.locale = targetLocale;
1408                    bundle = putBundleInCache(cacheKey, bundle, control);
1409                    return bundle;
1410                }
1411
1412                // Put NONEXISTENT_BUNDLE in the cache as a mark that there's no bundle
1413                // instance for the locale.
1414                putBundleInCache(cacheKey, NONEXISTENT_BUNDLE, control);
1415            } finally {
1416                if (constKey.getCause() instanceof InterruptedException) {
1417                    Thread.currentThread().interrupt();
1418                }
1419            }
1420        }
1421        return parent;
1422    }
1423
1424    private static final ResourceBundle loadBundle(CacheKey cacheKey,
1425                                                   List<String> formats,
1426                                                   Control control,
1427                                                   boolean reload) {
1428
1429        // Here we actually load the bundle in the order of formats
1430        // specified by the getFormats() value.
1431        Locale targetLocale = cacheKey.getLocale();
1432
1433        ResourceBundle bundle = null;
1434        int size = formats.size();
1435        for (int i = 0; i < size; i++) {
1436            String format = formats.get(i);
1437            try {
1438                bundle = control.newBundle(cacheKey.getName(), targetLocale, format,
1439                                           cacheKey.getLoader(), reload);
1440            } catch (LinkageError error) {
1441                // We need to handle the LinkageError case due to
1442                // inconsistent case-sensitivity in ClassLoader.
1443                // See 6572242 for details.
1444                cacheKey.setCause(error);
1445            } catch (Exception cause) {
1446                cacheKey.setCause(cause);
1447            }
1448            if (bundle != null) {
1449                // Set the format in the cache key so that it can be
1450                // used when calling needsReload later.
1451                cacheKey.setFormat(format);
1452                bundle.name = cacheKey.getName();
1453                bundle.locale = targetLocale;
1454                // Bundle provider might reuse instances. So we should make
1455                // sure to clear the expired flag here.
1456                bundle.expired = false;
1457                break;
1458            }
1459        }
1460
1461        return bundle;
1462    }
1463
1464    private static final boolean isValidBundle(ResourceBundle bundle) {
1465        return bundle != null && bundle != NONEXISTENT_BUNDLE;
1466    }
1467
1468    /**
1469     * Determines whether any of resource bundles in the parent chain,
1470     * including the leaf, have expired.
1471     */
1472    private static final boolean hasValidParentChain(ResourceBundle bundle) {
1473        long now = System.currentTimeMillis();
1474        while (bundle != null) {
1475            if (bundle.expired) {
1476                return false;
1477            }
1478            CacheKey key = bundle.cacheKey;
1479            if (key != null) {
1480                long expirationTime = key.expirationTime;
1481                if (expirationTime >= 0 && expirationTime <= now) {
1482                    return false;
1483                }
1484            }
1485            bundle = bundle.parent;
1486        }
1487        return true;
1488    }
1489
1490    /**
1491     * Throw a MissingResourceException with proper message
1492     */
1493    private static final void throwMissingResourceException(String baseName,
1494                                                            Locale locale,
1495                                                            Throwable cause) {
1496        // If the cause is a MissingResourceException, avoid creating
1497        // a long chain. (6355009)
1498        if (cause instanceof MissingResourceException) {
1499            cause = null;
1500        }
1501        throw new MissingResourceException("Can't find bundle for base name "
1502                                           + baseName + ", locale " + locale,
1503                                           baseName + "_" + locale, // className
1504                                           "",                      // key
1505                                           cause);
1506    }
1507
1508    /**
1509     * Finds a bundle in the cache. Any expired bundles are marked as
1510     * `expired' and removed from the cache upon return.
1511     *
1512     * @param cacheKey the key to look up the cache
1513     * @param control the Control to be used for the expiration control
1514     * @return the cached bundle, or null if the bundle is not found in the
1515     * cache or its parent has expired. <code>bundle.expire</code> is true
1516     * upon return if the bundle in the cache has expired.
1517     */
1518    private static final ResourceBundle findBundleInCache(CacheKey cacheKey,
1519                                                          Control control) {
1520        BundleReference bundleRef = cacheList.get(cacheKey);
1521        if (bundleRef == null) {
1522            return null;
1523        }
1524        ResourceBundle bundle = bundleRef.get();
1525        if (bundle == null) {
1526            return null;
1527        }
1528        ResourceBundle p = bundle.parent;
1529        assert p != NONEXISTENT_BUNDLE;
1530        // If the parent has expired, then this one must also expire. We
1531        // check only the immediate parent because the actual loading is
1532        // done from the root (base) to leaf (child) and the purpose of
1533        // checking is to propagate expiration towards the leaf. For
1534        // example, if the requested locale is ja_JP_JP and there are
1535        // bundles for all of the candidates in the cache, we have a list,
1536        //
1537        // base <- ja <- ja_JP <- ja_JP_JP
1538        //
1539        // If ja has expired, then it will reload ja and the list becomes a
1540        // tree.
1541        //
1542        // base <- ja (new)
1543        //  "   <- ja (expired) <- ja_JP <- ja_JP_JP
1544        //
1545        // When looking up ja_JP in the cache, it finds ja_JP in the cache
1546        // which references to the expired ja. Then, ja_JP is marked as
1547        // expired and removed from the cache. This will be propagated to
1548        // ja_JP_JP.
1549        //
1550        // Now, it's possible, for example, that while loading new ja_JP,
1551        // someone else has started loading the same bundle and finds the
1552        // base bundle has expired. Then, what we get from the first
1553        // getBundle call includes the expired base bundle. However, if
1554        // someone else didn't start its loading, we wouldn't know if the
1555        // base bundle has expired at the end of the loading process. The
1556        // expiration control doesn't guarantee that the returned bundle and
1557        // its parents haven't expired.
1558        //
1559        // We could check the entire parent chain to see if there's any in
1560        // the chain that has expired. But this process may never end. An
1561        // extreme case would be that getTimeToLive returns 0 and
1562        // needsReload always returns true.
1563        if (p != null && p.expired) {
1564            assert bundle != NONEXISTENT_BUNDLE;
1565            bundle.expired = true;
1566            bundle.cacheKey = null;
1567            cacheList.remove(cacheKey, bundleRef);
1568            bundle = null;
1569        } else {
1570            CacheKey key = bundleRef.getCacheKey();
1571            long expirationTime = key.expirationTime;
1572            if (!bundle.expired && expirationTime >= 0 &&
1573                expirationTime <= System.currentTimeMillis()) {
1574                // its TTL period has expired.
1575                if (bundle != NONEXISTENT_BUNDLE) {
1576                    // Synchronize here to call needsReload to avoid
1577                    // redundant concurrent calls for the same bundle.
1578                    synchronized (bundle) {
1579                        expirationTime = key.expirationTime;
1580                        if (!bundle.expired && expirationTime >= 0 &&
1581                            expirationTime <= System.currentTimeMillis()) {
1582                            try {
1583                                bundle.expired = control.needsReload(key.getName(),
1584                                                                     key.getLocale(),
1585                                                                     key.getFormat(),
1586                                                                     key.getLoader(),
1587                                                                     bundle,
1588                                                                     key.loadTime);
1589                            } catch (Exception e) {
1590                                cacheKey.setCause(e);
1591                            }
1592                            if (bundle.expired) {
1593                                // If the bundle needs to be reloaded, then
1594                                // remove the bundle from the cache, but
1595                                // return the bundle with the expired flag
1596                                // on.
1597                                bundle.cacheKey = null;
1598                                cacheList.remove(cacheKey, bundleRef);
1599                            } else {
1600                                // Update the expiration control info. and reuse
1601                                // the same bundle instance
1602                                setExpirationTime(key, control);
1603                            }
1604                        }
1605                    }
1606                } else {
1607                    // We just remove NONEXISTENT_BUNDLE from the cache.
1608                    cacheList.remove(cacheKey, bundleRef);
1609                    bundle = null;
1610                }
1611            }
1612        }
1613        return bundle;
1614    }
1615
1616    /**
1617     * Put a new bundle in the cache.
1618     *
1619     * @param cacheKey the key for the resource bundle
1620     * @param bundle the resource bundle to be put in the cache
1621     * @return the ResourceBundle for the cacheKey; if someone has put
1622     * the bundle before this call, the one found in the cache is
1623     * returned.
1624     */
1625    private static final ResourceBundle putBundleInCache(CacheKey cacheKey,
1626                                                         ResourceBundle bundle,
1627                                                         Control control) {
1628        setExpirationTime(cacheKey, control);
1629        if (cacheKey.expirationTime != Control.TTL_DONT_CACHE) {
1630            CacheKey key = (CacheKey) cacheKey.clone();
1631            BundleReference bundleRef = new BundleReference(bundle, referenceQueue, key);
1632            bundle.cacheKey = key;
1633
1634            // Put the bundle in the cache if it's not been in the cache.
1635            BundleReference result = cacheList.putIfAbsent(key, bundleRef);
1636
1637            // If someone else has put the same bundle in the cache before
1638            // us and it has not expired, we should use the one in the cache.
1639            if (result != null) {
1640                ResourceBundle rb = result.get();
1641                if (rb != null && !rb.expired) {
1642                    // Clear the back link to the cache key
1643                    bundle.cacheKey = null;
1644                    bundle = rb;
1645                    // Clear the reference in the BundleReference so that
1646                    // it won't be enqueued.
1647                    bundleRef.clear();
1648                } else {
1649                    // Replace the invalid (garbage collected or expired)
1650                    // instance with the valid one.
1651                    cacheList.put(key, bundleRef);
1652                }
1653            }
1654        }
1655        return bundle;
1656    }
1657
1658    private static final void setExpirationTime(CacheKey cacheKey, Control control) {
1659        long ttl = control.getTimeToLive(cacheKey.getName(),
1660                                         cacheKey.getLocale());
1661        if (ttl >= 0) {
1662            // If any expiration time is specified, set the time to be
1663            // expired in the cache.
1664            long now = System.currentTimeMillis();
1665            cacheKey.loadTime = now;
1666            cacheKey.expirationTime = now + ttl;
1667        } else if (ttl >= Control.TTL_NO_EXPIRATION_CONTROL) {
1668            cacheKey.expirationTime = ttl;
1669        } else {
1670            throw new IllegalArgumentException("Invalid Control: TTL=" + ttl);
1671        }
1672    }
1673
1674    /**
1675     * Removes all resource bundles from the cache that have been loaded
1676     * using the caller's class loader.
1677     *
1678     * @since 1.6
1679     * @see ResourceBundle.Control#getTimeToLive(String,Locale)
1680     */
1681    @CallerSensitive
1682    public static final void clearCache() {
1683        clearCache(getLoader(VMStack.getCallingClassLoader()));
1684    }
1685
1686    /**
1687     * Removes all resource bundles from the cache that have been loaded
1688     * using the given class loader.
1689     *
1690     * @param loader the class loader
1691     * @exception NullPointerException if <code>loader</code> is null
1692     * @since 1.6
1693     * @see ResourceBundle.Control#getTimeToLive(String,Locale)
1694     */
1695    public static final void clearCache(ClassLoader loader) {
1696        if (loader == null) {
1697            throw new NullPointerException();
1698        }
1699        Set<CacheKey> set = cacheList.keySet();
1700        for (CacheKey key : set) {
1701            if (key.getLoader() == loader) {
1702                set.remove(key);
1703            }
1704        }
1705    }
1706
1707    /**
1708     * Gets an object for the given key from this resource bundle.
1709     * Returns null if this resource bundle does not contain an
1710     * object for the given key.
1711     *
1712     * @param key the key for the desired object
1713     * @exception NullPointerException if <code>key</code> is <code>null</code>
1714     * @return the object for the given key, or null
1715     */
1716    protected abstract Object handleGetObject(String key);
1717
1718    /**
1719     * Returns an enumeration of the keys.
1720     *
1721     * @return an <code>Enumeration</code> of the keys contained in
1722     *         this <code>ResourceBundle</code> and its parent bundles.
1723     */
1724    public abstract Enumeration<String> getKeys();
1725
1726    /**
1727     * Determines whether the given <code>key</code> is contained in
1728     * this <code>ResourceBundle</code> or its parent bundles.
1729     *
1730     * @param key
1731     *        the resource <code>key</code>
1732     * @return <code>true</code> if the given <code>key</code> is
1733     *        contained in this <code>ResourceBundle</code> or its
1734     *        parent bundles; <code>false</code> otherwise.
1735     * @exception NullPointerException
1736     *         if <code>key</code> is <code>null</code>
1737     * @since 1.6
1738     */
1739    public boolean containsKey(String key) {
1740        if (key == null) {
1741            throw new NullPointerException();
1742        }
1743        for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
1744            if (rb.handleKeySet().contains(key)) {
1745                return true;
1746            }
1747        }
1748        return false;
1749    }
1750
1751    /**
1752     * Returns a <code>Set</code> of all keys contained in this
1753     * <code>ResourceBundle</code> and its parent bundles.
1754     *
1755     * @return a <code>Set</code> of all keys contained in this
1756     *         <code>ResourceBundle</code> and its parent bundles.
1757     * @since 1.6
1758     */
1759    public Set<String> keySet() {
1760        Set<String> keys = new HashSet<>();
1761        for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
1762            keys.addAll(rb.handleKeySet());
1763        }
1764        return keys;
1765    }
1766
1767    /**
1768     * Returns a <code>Set</code> of the keys contained <em>only</em>
1769     * in this <code>ResourceBundle</code>.
1770     *
1771     * <p>The default implementation returns a <code>Set</code> of the
1772     * keys returned by the {@link #getKeys() getKeys} method except
1773     * for the ones for which the {@link #handleGetObject(String)
1774     * handleGetObject} method returns <code>null</code>. Once the
1775     * <code>Set</code> has been created, the value is kept in this
1776     * <code>ResourceBundle</code> in order to avoid producing the
1777     * same <code>Set</code> in subsequent calls. Subclasses can
1778     * override this method for faster handling.
1779     *
1780     * @return a <code>Set</code> of the keys contained only in this
1781     *        <code>ResourceBundle</code>
1782     * @since 1.6
1783     */
1784    protected Set<String> handleKeySet() {
1785        if (keySet == null) {
1786            synchronized (this) {
1787                if (keySet == null) {
1788                    Set<String> keys = new HashSet<>();
1789                    Enumeration<String> enumKeys = getKeys();
1790                    while (enumKeys.hasMoreElements()) {
1791                        String key = enumKeys.nextElement();
1792                        if (handleGetObject(key) != null) {
1793                            keys.add(key);
1794                        }
1795                    }
1796                    keySet = keys;
1797                }
1798            }
1799        }
1800        return keySet;
1801    }
1802
1803
1804
1805    /**
1806     * <code>ResourceBundle.Control</code> defines a set of callback methods
1807     * that are invoked by the {@link ResourceBundle#getBundle(String,
1808     * Locale, ClassLoader, Control) ResourceBundle.getBundle} factory
1809     * methods during the bundle loading process. In other words, a
1810     * <code>ResourceBundle.Control</code> collaborates with the factory
1811     * methods for loading resource bundles. The default implementation of
1812     * the callback methods provides the information necessary for the
1813     * factory methods to perform the <a
1814     * href="./ResourceBundle.html#default_behavior">default behavior</a>.
1815     *
1816     * <p>In addition to the callback methods, the {@link
1817     * #toBundleName(String, Locale) toBundleName} and {@link
1818     * #toResourceName(String, String) toResourceName} methods are defined
1819     * primarily for convenience in implementing the callback
1820     * methods. However, the <code>toBundleName</code> method could be
1821     * overridden to provide different conventions in the organization and
1822     * packaging of localized resources.  The <code>toResourceName</code>
1823     * method is <code>final</code> to avoid use of wrong resource and class
1824     * name separators.
1825     *
1826     * <p>Two factory methods, {@link #getControl(List)} and {@link
1827     * #getNoFallbackControl(List)}, provide
1828     * <code>ResourceBundle.Control</code> instances that implement common
1829     * variations of the default bundle loading process.
1830     *
1831     * <p>The formats returned by the {@link Control#getFormats(String)
1832     * getFormats} method and candidate locales returned by the {@link
1833     * ResourceBundle.Control#getCandidateLocales(String, Locale)
1834     * getCandidateLocales} method must be consistent in all
1835     * <code>ResourceBundle.getBundle</code> invocations for the same base
1836     * bundle. Otherwise, the <code>ResourceBundle.getBundle</code> methods
1837     * may return unintended bundles. For example, if only
1838     * <code>"java.class"</code> is returned by the <code>getFormats</code>
1839     * method for the first call to <code>ResourceBundle.getBundle</code>
1840     * and only <code>"java.properties"</code> for the second call, then the
1841     * second call will return the class-based one that has been cached
1842     * during the first call.
1843     *
1844     * <p>A <code>ResourceBundle.Control</code> instance must be thread-safe
1845     * if it's simultaneously used by multiple threads.
1846     * <code>ResourceBundle.getBundle</code> does not synchronize to call
1847     * the <code>ResourceBundle.Control</code> methods. The default
1848     * implementations of the methods are thread-safe.
1849     *
1850     * <p>Applications can specify <code>ResourceBundle.Control</code>
1851     * instances returned by the <code>getControl</code> factory methods or
1852     * created from a subclass of <code>ResourceBundle.Control</code> to
1853     * customize the bundle loading process. The following are examples of
1854     * changing the default bundle loading process.
1855     *
1856     * <p><b>Example 1</b>
1857     *
1858     * <p>The following code lets <code>ResourceBundle.getBundle</code> look
1859     * up only properties-based resources.
1860     *
1861     * <pre>
1862     * import java.util.*;
1863     * import static java.util.ResourceBundle.Control.*;
1864     * ...
1865     * ResourceBundle bundle =
1866     *   ResourceBundle.getBundle("MyResources", new Locale("fr", "CH"),
1867     *                            ResourceBundle.Control.getControl(FORMAT_PROPERTIES));
1868     * </pre>
1869     *
1870     * Given the resource bundles in the <a
1871     * href="./ResourceBundle.html#default_behavior_example">example</a> in
1872     * the <code>ResourceBundle.getBundle</code> description, this
1873     * <code>ResourceBundle.getBundle</code> call loads
1874     * <code>MyResources_fr_CH.properties</code> whose parent is
1875     * <code>MyResources_fr.properties</code> whose parent is
1876     * <code>MyResources.properties</code>. (<code>MyResources_fr_CH.properties</code>
1877     * is not hidden, but <code>MyResources_fr_CH.class</code> is.)
1878     *
1879     * <p><b>Example 2</b>
1880     *
1881     * <p>The following is an example of loading XML-based bundles
1882     * using {@link Properties#loadFromXML(java.io.InputStream)
1883     * Properties.loadFromXML}.
1884     *
1885     * <pre>
1886     * ResourceBundle rb = ResourceBundle.getBundle("Messages",
1887     *     new ResourceBundle.Control() {
1888     *         public List&lt;String&gt; getFormats(String baseName) {
1889     *             if (baseName == null)
1890     *                 throw new NullPointerException();
1891     *             return Arrays.asList("xml");
1892     *         }
1893     *         public ResourceBundle newBundle(String baseName,
1894     *                                         Locale locale,
1895     *                                         String format,
1896     *                                         ClassLoader loader,
1897     *                                         boolean reload)
1898     *                          throws IllegalAccessException,
1899     *                                 InstantiationException,
1900     *                                 IOException {
1901     *             if (baseName == null || locale == null
1902     *                   || format == null || loader == null)
1903     *                 throw new NullPointerException();
1904     *             ResourceBundle bundle = null;
1905     *             if (format.equals("xml")) {
1906     *                 String bundleName = toBundleName(baseName, locale);
1907     *                 String resourceName = toResourceName(bundleName, format);
1908     *                 InputStream stream = null;
1909     *                 if (reload) {
1910     *                     URL url = loader.getResource(resourceName);
1911     *                     if (url != null) {
1912     *                         URLConnection connection = url.openConnection();
1913     *                         if (connection != null) {
1914     *                             // Disable caches to get fresh data for
1915     *                             // reloading.
1916     *                             connection.setUseCaches(false);
1917     *                             stream = connection.getInputStream();
1918     *                         }
1919     *                     }
1920     *                 } else {
1921     *                     stream = loader.getResourceAsStream(resourceName);
1922     *                 }
1923     *                 if (stream != null) {
1924     *                     BufferedInputStream bis = new BufferedInputStream(stream);
1925     *                     bundle = new XMLResourceBundle(bis);
1926     *                     bis.close();
1927     *                 }
1928     *             }
1929     *             return bundle;
1930     *         }
1931     *     });
1932     *
1933     * ...
1934     *
1935     * private static class XMLResourceBundle extends ResourceBundle {
1936     *     private Properties props;
1937     *     XMLResourceBundle(InputStream stream) throws IOException {
1938     *         props = new Properties();
1939     *         props.loadFromXML(stream);
1940     *     }
1941     *     protected Object handleGetObject(String key) {
1942     *         return props.getProperty(key);
1943     *     }
1944     *     public Enumeration&lt;String&gt; getKeys() {
1945     *         ...
1946     *     }
1947     * }
1948     * </pre>
1949     *
1950     * @since 1.6
1951     */
1952    public static class Control {
1953        /**
1954         * The default format <code>List</code>, which contains the strings
1955         * <code>"java.class"</code> and <code>"java.properties"</code>, in
1956         * this order. This <code>List</code> is {@linkplain
1957         * Collections#unmodifiableList(List) unmodifiable}.
1958         *
1959         * @see #getFormats(String)
1960         */
1961        public static final List<String> FORMAT_DEFAULT
1962            = Collections.unmodifiableList(Arrays.asList("java.class",
1963                                                         "java.properties"));
1964
1965        /**
1966         * The class-only format <code>List</code> containing
1967         * <code>"java.class"</code>. This <code>List</code> is {@linkplain
1968         * Collections#unmodifiableList(List) unmodifiable}.
1969         *
1970         * @see #getFormats(String)
1971         */
1972        public static final List<String> FORMAT_CLASS
1973            = Collections.unmodifiableList(Arrays.asList("java.class"));
1974
1975        /**
1976         * The properties-only format <code>List</code> containing
1977         * <code>"java.properties"</code>. This <code>List</code> is
1978         * {@linkplain Collections#unmodifiableList(List) unmodifiable}.
1979         *
1980         * @see #getFormats(String)
1981         */
1982        public static final List<String> FORMAT_PROPERTIES
1983            = Collections.unmodifiableList(Arrays.asList("java.properties"));
1984
1985        /**
1986         * The time-to-live constant for not caching loaded resource bundle
1987         * instances.
1988         *
1989         * @see #getTimeToLive(String, Locale)
1990         */
1991        public static final long TTL_DONT_CACHE = -1;
1992
1993        /**
1994         * The time-to-live constant for disabling the expiration control
1995         * for loaded resource bundle instances in the cache.
1996         *
1997         * @see #getTimeToLive(String, Locale)
1998         */
1999        public static final long TTL_NO_EXPIRATION_CONTROL = -2;
2000
2001        private static final Control INSTANCE = new Control();
2002
2003        /**
2004         * Sole constructor. (For invocation by subclass constructors,
2005         * typically implicit.)
2006         */
2007        protected Control() {
2008        }
2009
2010        /**
2011         * Returns a <code>ResourceBundle.Control</code> in which the {@link
2012         * #getFormats(String) getFormats} method returns the specified
2013         * <code>formats</code>. The <code>formats</code> must be equal to
2014         * one of {@link Control#FORMAT_PROPERTIES}, {@link
2015         * Control#FORMAT_CLASS} or {@link
2016         * Control#FORMAT_DEFAULT}. <code>ResourceBundle.Control</code>
2017         * instances returned by this method are singletons and thread-safe.
2018         *
2019         * <p>Specifying {@link Control#FORMAT_DEFAULT} is equivalent to
2020         * instantiating the <code>ResourceBundle.Control</code> class,
2021         * except that this method returns a singleton.
2022         *
2023         * @param formats
2024         *        the formats to be returned by the
2025         *        <code>ResourceBundle.Control.getFormats</code> method
2026         * @return a <code>ResourceBundle.Control</code> supporting the
2027         *        specified <code>formats</code>
2028         * @exception NullPointerException
2029         *        if <code>formats</code> is <code>null</code>
2030         * @exception IllegalArgumentException
2031         *        if <code>formats</code> is unknown
2032         */
2033        public static final Control getControl(List<String> formats) {
2034            if (formats.equals(Control.FORMAT_PROPERTIES)) {
2035                return SingleFormatControl.PROPERTIES_ONLY;
2036            }
2037            if (formats.equals(Control.FORMAT_CLASS)) {
2038                return SingleFormatControl.CLASS_ONLY;
2039            }
2040            if (formats.equals(Control.FORMAT_DEFAULT)) {
2041                return Control.INSTANCE;
2042            }
2043            throw new IllegalArgumentException();
2044        }
2045
2046        /**
2047         * Returns a <code>ResourceBundle.Control</code> in which the {@link
2048         * #getFormats(String) getFormats} method returns the specified
2049         * <code>formats</code> and the {@link
2050         * Control#getFallbackLocale(String, Locale) getFallbackLocale}
2051         * method returns <code>null</code>. The <code>formats</code> must
2052         * be equal to one of {@link Control#FORMAT_PROPERTIES}, {@link
2053         * Control#FORMAT_CLASS} or {@link Control#FORMAT_DEFAULT}.
2054         * <code>ResourceBundle.Control</code> instances returned by this
2055         * method are singletons and thread-safe.
2056         *
2057         * @param formats
2058         *        the formats to be returned by the
2059         *        <code>ResourceBundle.Control.getFormats</code> method
2060         * @return a <code>ResourceBundle.Control</code> supporting the
2061         *        specified <code>formats</code> with no fallback
2062         *        <code>Locale</code> support
2063         * @exception NullPointerException
2064         *        if <code>formats</code> is <code>null</code>
2065         * @exception IllegalArgumentException
2066         *        if <code>formats</code> is unknown
2067         */
2068        public static final Control getNoFallbackControl(List<String> formats) {
2069            if (formats.equals(Control.FORMAT_DEFAULT)) {
2070                return NoFallbackControl.NO_FALLBACK;
2071            }
2072            if (formats.equals(Control.FORMAT_PROPERTIES)) {
2073                return NoFallbackControl.PROPERTIES_ONLY_NO_FALLBACK;
2074            }
2075            if (formats.equals(Control.FORMAT_CLASS)) {
2076                return NoFallbackControl.CLASS_ONLY_NO_FALLBACK;
2077            }
2078            throw new IllegalArgumentException();
2079        }
2080
2081        /**
2082         * Returns a <code>List</code> of <code>String</code>s containing
2083         * formats to be used to load resource bundles for the given
2084         * <code>baseName</code>. The <code>ResourceBundle.getBundle</code>
2085         * factory method tries to load resource bundles with formats in the
2086         * order specified by the list. The list returned by this method
2087         * must have at least one <code>String</code>. The predefined
2088         * formats are <code>"java.class"</code> for class-based resource
2089         * bundles and <code>"java.properties"</code> for {@linkplain
2090         * PropertyResourceBundle properties-based} ones. Strings starting
2091         * with <code>"java."</code> are reserved for future extensions and
2092         * must not be used by application-defined formats.
2093         *
2094         * <p>It is not a requirement to return an immutable (unmodifiable)
2095         * <code>List</code>.  However, the returned <code>List</code> must
2096         * not be mutated after it has been returned by
2097         * <code>getFormats</code>.
2098         *
2099         * <p>The default implementation returns {@link #FORMAT_DEFAULT} so
2100         * that the <code>ResourceBundle.getBundle</code> factory method
2101         * looks up first class-based resource bundles, then
2102         * properties-based ones.
2103         *
2104         * @param baseName
2105         *        the base name of the resource bundle, a fully qualified class
2106         *        name
2107         * @return a <code>List</code> of <code>String</code>s containing
2108         *        formats for loading resource bundles.
2109         * @exception NullPointerException
2110         *        if <code>baseName</code> is null
2111         * @see #FORMAT_DEFAULT
2112         * @see #FORMAT_CLASS
2113         * @see #FORMAT_PROPERTIES
2114         */
2115        public List<String> getFormats(String baseName) {
2116            if (baseName == null) {
2117                throw new NullPointerException();
2118            }
2119            return FORMAT_DEFAULT;
2120        }
2121
2122        /**
2123         * Returns a <code>List</code> of <code>Locale</code>s as candidate
2124         * locales for <code>baseName</code> and <code>locale</code>. This
2125         * method is called by the <code>ResourceBundle.getBundle</code>
2126         * factory method each time the factory method tries finding a
2127         * resource bundle for a target <code>Locale</code>.
2128         *
2129         * <p>The sequence of the candidate locales also corresponds to the
2130         * runtime resource lookup path (also known as the <I>parent
2131         * chain</I>), if the corresponding resource bundles for the
2132         * candidate locales exist and their parents are not defined by
2133         * loaded resource bundles themselves.  The last element of the list
2134         * must be a {@linkplain Locale#ROOT root locale} if it is desired to
2135         * have the base bundle as the terminal of the parent chain.
2136         *
2137         * <p>If the given locale is equal to <code>Locale.ROOT</code> (the
2138         * root locale), a <code>List</code> containing only the root
2139         * <code>Locale</code> must be returned. In this case, the
2140         * <code>ResourceBundle.getBundle</code> factory method loads only
2141         * the base bundle as the resulting resource bundle.
2142         *
2143         * <p>It is not a requirement to return an immutable (unmodifiable)
2144         * <code>List</code>. However, the returned <code>List</code> must not
2145         * be mutated after it has been returned by
2146         * <code>getCandidateLocales</code>.
2147         *
2148         * <p>The default implementation returns a <code>List</code> containing
2149         * <code>Locale</code>s using the rules described below.  In the
2150         * description below, <em>L</em>, <em>S</em>, <em>C</em> and <em>V</em>
2151         * respectively represent non-empty language, script, country, and
2152         * variant.  For example, [<em>L</em>, <em>C</em>] represents a
2153         * <code>Locale</code> that has non-empty values only for language and
2154         * country.  The form <em>L</em>("xx") represents the (non-empty)
2155         * language value is "xx".  For all cases, <code>Locale</code>s whose
2156         * final component values are empty strings are omitted.
2157         *
2158         * <ol><li>For an input <code>Locale</code> with an empty script value,
2159         * append candidate <code>Locale</code>s by omitting the final component
2160         * one by one as below:
2161         *
2162         * <ul>
2163         * <li> [<em>L</em>, <em>C</em>, <em>V</em>]
2164         * <li> [<em>L</em>, <em>C</em>]
2165         * <li> [<em>L</em>]
2166         * <li> <code>Locale.ROOT</code>
2167         * </ul>
2168         *
2169         * <li>For an input <code>Locale</code> with a non-empty script value,
2170         * append candidate <code>Locale</code>s by omitting the final component
2171         * up to language, then append candidates generated from the
2172         * <code>Locale</code> with country and variant restored:
2173         *
2174         * <ul>
2175         * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V</em>]
2176         * <li> [<em>L</em>, <em>S</em>, <em>C</em>]
2177         * <li> [<em>L</em>, <em>S</em>]
2178         * <li> [<em>L</em>, <em>C</em>, <em>V</em>]
2179         * <li> [<em>L</em>, <em>C</em>]
2180         * <li> [<em>L</em>]
2181         * <li> <code>Locale.ROOT</code>
2182         * </ul>
2183         *
2184         * <li>For an input <code>Locale</code> with a variant value consisting
2185         * of multiple subtags separated by underscore, generate candidate
2186         * <code>Locale</code>s by omitting the variant subtags one by one, then
2187         * insert them after every occurence of <code> Locale</code>s with the
2188         * full variant value in the original list.  For example, if the
2189         * the variant consists of two subtags <em>V1</em> and <em>V2</em>:
2190         *
2191         * <ul>
2192         * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V1</em>, <em>V2</em>]
2193         * <li> [<em>L</em>, <em>S</em>, <em>C</em>, <em>V1</em>]
2194         * <li> [<em>L</em>, <em>S</em>, <em>C</em>]
2195         * <li> [<em>L</em>, <em>S</em>]
2196         * <li> [<em>L</em>, <em>C</em>, <em>V1</em>, <em>V2</em>]
2197         * <li> [<em>L</em>, <em>C</em>, <em>V1</em>]
2198         * <li> [<em>L</em>, <em>C</em>]
2199         * <li> [<em>L</em>]
2200         * <li> <code>Locale.ROOT</code>
2201         * </ul>
2202         *
2203         * <li>Special cases for Chinese.  When an input <code>Locale</code> has the
2204         * language "zh" (Chinese) and an empty script value, either "Hans" (Simplified) or
2205         * "Hant" (Traditional) might be supplied, depending on the country.
2206         * When the country is "CN" (China) or "SG" (Singapore), "Hans" is supplied.
2207         * When the country is "HK" (Hong Kong SAR China), "MO" (Macau SAR China),
2208         * or "TW" (Taiwan), "Hant" is supplied.  For all other countries or when the country
2209         * is empty, no script is supplied.  For example, for <code>Locale("zh", "CN")
2210         * </code>, the candidate list will be:
2211         * <ul>
2212         * <li> [<em>L</em>("zh"), <em>S</em>("Hans"), <em>C</em>("CN")]
2213         * <li> [<em>L</em>("zh"), <em>S</em>("Hans")]
2214         * <li> [<em>L</em>("zh"), <em>C</em>("CN")]
2215         * <li> [<em>L</em>("zh")]
2216         * <li> <code>Locale.ROOT</code>
2217         * </ul>
2218         *
2219         * For <code>Locale("zh", "TW")</code>, the candidate list will be:
2220         * <ul>
2221         * <li> [<em>L</em>("zh"), <em>S</em>("Hant"), <em>C</em>("TW")]
2222         * <li> [<em>L</em>("zh"), <em>S</em>("Hant")]
2223         * <li> [<em>L</em>("zh"), <em>C</em>("TW")]
2224         * <li> [<em>L</em>("zh")]
2225         * <li> <code>Locale.ROOT</code>
2226         * </ul>
2227         *
2228         * <li>Special cases for Norwegian.  Both <code>Locale("no", "NO",
2229         * "NY")</code> and <code>Locale("nn", "NO")</code> represent Norwegian
2230         * Nynorsk.  When a locale's language is "nn", the standard candidate
2231         * list is generated up to [<em>L</em>("nn")], and then the following
2232         * candidates are added:
2233         *
2234         * <ul><li> [<em>L</em>("no"), <em>C</em>("NO"), <em>V</em>("NY")]
2235         * <li> [<em>L</em>("no"), <em>C</em>("NO")]
2236         * <li> [<em>L</em>("no")]
2237         * <li> <code>Locale.ROOT</code>
2238         * </ul>
2239         *
2240         * If the locale is exactly <code>Locale("no", "NO", "NY")</code>, it is first
2241         * converted to <code>Locale("nn", "NO")</code> and then the above procedure is
2242         * followed.
2243         *
2244         * <p>Also, Java treats the language "no" as a synonym of Norwegian
2245         * Bokm&#xE5;l "nb".  Except for the single case <code>Locale("no",
2246         * "NO", "NY")</code> (handled above), when an input <code>Locale</code>
2247         * has language "no" or "nb", candidate <code>Locale</code>s with
2248         * language code "no" and "nb" are interleaved, first using the
2249         * requested language, then using its synonym. For example,
2250         * <code>Locale("nb", "NO", "POSIX")</code> generates the following
2251         * candidate list:
2252         *
2253         * <ul>
2254         * <li> [<em>L</em>("nb"), <em>C</em>("NO"), <em>V</em>("POSIX")]
2255         * <li> [<em>L</em>("no"), <em>C</em>("NO"), <em>V</em>("POSIX")]
2256         * <li> [<em>L</em>("nb"), <em>C</em>("NO")]
2257         * <li> [<em>L</em>("no"), <em>C</em>("NO")]
2258         * <li> [<em>L</em>("nb")]
2259         * <li> [<em>L</em>("no")]
2260         * <li> <code>Locale.ROOT</code>
2261         * </ul>
2262         *
2263         * <code>Locale("no", "NO", "POSIX")</code> would generate the same list
2264         * except that locales with "no" would appear before the corresponding
2265         * locales with "nb".</li>
2266         *
2267         * </li>
2268         * </ol>
2269         *
2270         * <p>The default implementation uses an {@link ArrayList} that
2271         * overriding implementations may modify before returning it to the
2272         * caller. However, a subclass must not modify it after it has
2273         * been returned by <code>getCandidateLocales</code>.
2274         *
2275         * <p>For example, if the given <code>baseName</code> is "Messages"
2276         * and the given <code>locale</code> is
2277         * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then a
2278         * <code>List</code> of <code>Locale</code>s:
2279         * <pre>
2280         *     Locale("ja", "", "XX")
2281         *     Locale("ja")
2282         *     Locale.ROOT
2283         * </pre>
2284         * is returned. And if the resource bundles for the "ja" and
2285         * "" <code>Locale</code>s are found, then the runtime resource
2286         * lookup path (parent chain) is:
2287         * <pre>
2288         *     Messages_ja -> Messages
2289         * </pre>
2290         *
2291         * @param baseName
2292         *        the base name of the resource bundle, a fully
2293         *        qualified class name
2294         * @param locale
2295         *        the locale for which a resource bundle is desired
2296         * @return a <code>List</code> of candidate
2297         *        <code>Locale</code>s for the given <code>locale</code>
2298         * @exception NullPointerException
2299         *        if <code>baseName</code> or <code>locale</code> is
2300         *        <code>null</code>
2301         */
2302        public List<Locale> getCandidateLocales(String baseName, Locale locale) {
2303            if (baseName == null) {
2304                throw new NullPointerException();
2305            }
2306            return new ArrayList<>(CANDIDATES_CACHE.get(locale.getBaseLocale()));
2307        }
2308
2309        private static final CandidateListCache CANDIDATES_CACHE = new CandidateListCache();
2310
2311        private static class CandidateListCache extends LocaleObjectCache<BaseLocale, List<Locale>> {
2312            protected List<Locale> createObject(BaseLocale base) {
2313                String language = base.getLanguage();
2314                String script = base.getScript();
2315                String region = base.getRegion();
2316                String variant = base.getVariant();
2317
2318                // Special handling for Norwegian
2319                boolean isNorwegianBokmal = false;
2320                boolean isNorwegianNynorsk = false;
2321                if (language.equals("no")) {
2322                    if (region.equals("NO") && variant.equals("NY")) {
2323                        variant = "";
2324                        isNorwegianNynorsk = true;
2325                    } else {
2326                        isNorwegianBokmal = true;
2327                    }
2328                }
2329                if (language.equals("nb") || isNorwegianBokmal) {
2330                    List<Locale> tmpList = getDefaultList("nb", script, region, variant);
2331                    // Insert a locale replacing "nb" with "no" for every list entry
2332                    List<Locale> bokmalList = new LinkedList<>();
2333                    for (Locale l : tmpList) {
2334                        bokmalList.add(l);
2335                        if (l.getLanguage().length() == 0) {
2336                            break;
2337                        }
2338                        bokmalList.add(Locale.getInstance("no", l.getScript(), l.getCountry(),
2339                                l.getVariant(), null));
2340                    }
2341                    return bokmalList;
2342                } else if (language.equals("nn") || isNorwegianNynorsk) {
2343                    // Insert no_NO_NY, no_NO, no after nn
2344                    List<Locale> nynorskList = getDefaultList("nn", script, region, variant);
2345                    int idx = nynorskList.size() - 1;
2346                    nynorskList.add(idx++, Locale.getInstance("no", "NO", "NY"));
2347                    nynorskList.add(idx++, Locale.getInstance("no", "NO", ""));
2348                    nynorskList.add(idx++, Locale.getInstance("no", "", ""));
2349                    return nynorskList;
2350                }
2351                // Special handling for Chinese
2352                else if (language.equals("zh")) {
2353                    if (script.length() == 0 && region.length() > 0) {
2354                        // Supply script for users who want to use zh_Hans/zh_Hant
2355                        // as bundle names (recommended for Java7+)
2356                        if (region.equals("TW") || region.equals("HK") || region.equals("MO")) {
2357                            script = "Hant";
2358                        } else if (region.equals("CN") || region.equals("SG")) {
2359                            script = "Hans";
2360                        }
2361                    } else if (script.length() > 0 && region.length() == 0) {
2362                        // Supply region(country) for users who still package Chinese
2363                        // bundles using old convension.
2364                        if (script.equals("Hans")) {
2365                            region = "CN";
2366                        } else if (script.equals("Hant")) {
2367                            region = "TW";
2368                        }
2369                    }
2370                }
2371
2372                return getDefaultList(language, script, region, variant);
2373            }
2374
2375            private static List<Locale> getDefaultList(String language, String script, String region, String variant) {
2376                List<String> variants = null;
2377
2378                if (variant.length() > 0) {
2379                    variants = new LinkedList<>();
2380                    int idx = variant.length();
2381                    while (idx != -1) {
2382                        variants.add(variant.substring(0, idx));
2383                        idx = variant.lastIndexOf('_', --idx);
2384                    }
2385                }
2386
2387                List<Locale> list = new LinkedList<>();
2388
2389                if (variants != null) {
2390                    for (String v : variants) {
2391                        list.add(Locale.getInstance(language, script, region, v, null));
2392                    }
2393                }
2394                if (region.length() > 0) {
2395                    list.add(Locale.getInstance(language, script, region, "", null));
2396                }
2397                if (script.length() > 0) {
2398                    list.add(Locale.getInstance(language, script, "", "", null));
2399
2400                    // With script, after truncating variant, region and script,
2401                    // start over without script.
2402                    if (variants != null) {
2403                        for (String v : variants) {
2404                            list.add(Locale.getInstance(language, "", region, v, null));
2405                        }
2406                    }
2407                    if (region.length() > 0) {
2408                        list.add(Locale.getInstance(language, "", region, "", null));
2409                    }
2410                }
2411                if (language.length() > 0) {
2412                    list.add(Locale.getInstance(language, "", "", "", null));
2413                }
2414                // Add root locale at the end
2415                list.add(Locale.ROOT);
2416
2417                return list;
2418            }
2419        }
2420
2421        /**
2422         * Returns a <code>Locale</code> to be used as a fallback locale for
2423         * further resource bundle searches by the
2424         * <code>ResourceBundle.getBundle</code> factory method. This method
2425         * is called from the factory method every time when no resulting
2426         * resource bundle has been found for <code>baseName</code> and
2427         * <code>locale</code>, where locale is either the parameter for
2428         * <code>ResourceBundle.getBundle</code> or the previous fallback
2429         * locale returned by this method.
2430         *
2431         * <p>The method returns <code>null</code> if no further fallback
2432         * search is desired.
2433         *
2434         * <p>The default implementation returns the {@linkplain
2435         * Locale#getDefault() default <code>Locale</code>} if the given
2436         * <code>locale</code> isn't the default one.  Otherwise,
2437         * <code>null</code> is returned.
2438         *
2439         * @param baseName
2440         *        the base name of the resource bundle, a fully
2441         *        qualified class name for which
2442         *        <code>ResourceBundle.getBundle</code> has been
2443         *        unable to find any resource bundles (except for the
2444         *        base bundle)
2445         * @param locale
2446         *        the <code>Locale</code> for which
2447         *        <code>ResourceBundle.getBundle</code> has been
2448         *        unable to find any resource bundles (except for the
2449         *        base bundle)
2450         * @return a <code>Locale</code> for the fallback search,
2451         *        or <code>null</code> if no further fallback search
2452         *        is desired.
2453         * @exception NullPointerException
2454         *        if <code>baseName</code> or <code>locale</code>
2455         *        is <code>null</code>
2456         */
2457        public Locale getFallbackLocale(String baseName, Locale locale) {
2458            if (baseName == null) {
2459                throw new NullPointerException();
2460            }
2461            Locale defaultLocale = Locale.getDefault();
2462            return locale.equals(defaultLocale) ? null : defaultLocale;
2463        }
2464
2465        /**
2466         * Instantiates a resource bundle for the given bundle name of the
2467         * given format and locale, using the given class loader if
2468         * necessary. This method returns <code>null</code> if there is no
2469         * resource bundle available for the given parameters. If a resource
2470         * bundle can't be instantiated due to an unexpected error, the
2471         * error must be reported by throwing an <code>Error</code> or
2472         * <code>Exception</code> rather than simply returning
2473         * <code>null</code>.
2474         *
2475         * <p>If the <code>reload</code> flag is <code>true</code>, it
2476         * indicates that this method is being called because the previously
2477         * loaded resource bundle has expired.
2478         *
2479         * <p>The default implementation instantiates a
2480         * <code>ResourceBundle</code> as follows.
2481         *
2482         * <ul>
2483         *
2484         * <li>The bundle name is obtained by calling {@link
2485         * #toBundleName(String, Locale) toBundleName(baseName,
2486         * locale)}.</li>
2487         *
2488         * <li>If <code>format</code> is <code>"java.class"</code>, the
2489         * {@link Class} specified by the bundle name is loaded by calling
2490         * {@link ClassLoader#loadClass(String)}. Then, a
2491         * <code>ResourceBundle</code> is instantiated by calling {@link
2492         * Class#newInstance()}.  Note that the <code>reload</code> flag is
2493         * ignored for loading class-based resource bundles in this default
2494         * implementation.</li>
2495         *
2496         * <li>If <code>format</code> is <code>"java.properties"</code>,
2497         * {@link #toResourceName(String, String) toResourceName(bundlename,
2498         * "properties")} is called to get the resource name.
2499         * If <code>reload</code> is <code>true</code>, {@link
2500         * ClassLoader#getResource(String) load.getResource} is called
2501         * to get a {@link URL} for creating a {@link
2502         * URLConnection}. This <code>URLConnection</code> is used to
2503         * {@linkplain URLConnection#setUseCaches(boolean) disable the
2504         * caches} of the underlying resource loading layers,
2505         * and to {@linkplain URLConnection#getInputStream() get an
2506         * <code>InputStream</code>}.
2507         * Otherwise, {@link ClassLoader#getResourceAsStream(String)
2508         * loader.getResourceAsStream} is called to get an {@link
2509         * InputStream}. Then, a {@link
2510         * PropertyResourceBundle} is constructed with the
2511         * <code>InputStream</code>.</li>
2512         *
2513         * <li>If <code>format</code> is neither <code>"java.class"</code>
2514         * nor <code>"java.properties"</code>, an
2515         * <code>IllegalArgumentException</code> is thrown.</li>
2516         *
2517         * </ul>
2518         *
2519         * @param baseName
2520         *        the base bundle name of the resource bundle, a fully
2521         *        qualified class name
2522         * @param locale
2523         *        the locale for which the resource bundle should be
2524         *        instantiated
2525         * @param format
2526         *        the resource bundle format to be loaded
2527         * @param loader
2528         *        the <code>ClassLoader</code> to use to load the bundle
2529         * @param reload
2530         *        the flag to indicate bundle reloading; <code>true</code>
2531         *        if reloading an expired resource bundle,
2532         *        <code>false</code> otherwise
2533         * @return the resource bundle instance,
2534         *        or <code>null</code> if none could be found.
2535         * @exception NullPointerException
2536         *        if <code>bundleName</code>, <code>locale</code>,
2537         *        <code>format</code>, or <code>loader</code> is
2538         *        <code>null</code>, or if <code>null</code> is returned by
2539         *        {@link #toBundleName(String, Locale) toBundleName}
2540         * @exception IllegalArgumentException
2541         *        if <code>format</code> is unknown, or if the resource
2542         *        found for the given parameters contains malformed data.
2543         * @exception ClassCastException
2544         *        if the loaded class cannot be cast to <code>ResourceBundle</code>
2545         * @exception IllegalAccessException
2546         *        if the class or its nullary constructor is not
2547         *        accessible.
2548         * @exception InstantiationException
2549         *        if the instantiation of a class fails for some other
2550         *        reason.
2551         * @exception ExceptionInInitializerError
2552         *        if the initialization provoked by this method fails.
2553         * @exception SecurityException
2554         *        If a security manager is present and creation of new
2555         *        instances is denied. See {@link Class#newInstance()}
2556         *        for details.
2557         * @exception IOException
2558         *        if an error occurred when reading resources using
2559         *        any I/O operations
2560         */
2561        public ResourceBundle newBundle(String baseName, Locale locale, String format,
2562                                        ClassLoader loader, boolean reload)
2563                    throws IllegalAccessException, InstantiationException, IOException {
2564            String bundleName = toBundleName(baseName, locale);
2565            ResourceBundle bundle = null;
2566            if (format.equals("java.class")) {
2567                try {
2568                    Class<? extends ResourceBundle> bundleClass
2569                        = (Class<? extends ResourceBundle>)loader.loadClass(bundleName);
2570
2571                    // If the class isn't a ResourceBundle subclass, throw a
2572                    // ClassCastException.
2573                    if (ResourceBundle.class.isAssignableFrom(bundleClass)) {
2574                        bundle = bundleClass.newInstance();
2575                    } else {
2576                        throw new ClassCastException(bundleClass.getName()
2577                                     + " cannot be cast to ResourceBundle");
2578                    }
2579                } catch (ClassNotFoundException e) {
2580                }
2581            } else if (format.equals("java.properties")) {
2582                final String resourceName = toResourceName(bundleName, "properties");
2583                final ClassLoader classLoader = loader;
2584                final boolean reloadFlag = reload;
2585                InputStream stream = null;
2586                try {
2587                    stream = AccessController.doPrivileged(
2588                        new PrivilegedExceptionAction<InputStream>() {
2589                            public InputStream run() throws IOException {
2590                                InputStream is = null;
2591                                if (reloadFlag) {
2592                                    URL url = classLoader.getResource(resourceName);
2593                                    if (url != null) {
2594                                        URLConnection connection = url.openConnection();
2595                                        if (connection != null) {
2596                                            // Disable caches to get fresh data for
2597                                            // reloading.
2598                                            connection.setUseCaches(false);
2599                                            is = connection.getInputStream();
2600                                        }
2601                                    }
2602                                } else {
2603                                    is = classLoader.getResourceAsStream(resourceName);
2604                                }
2605                                return is;
2606                            }
2607                        });
2608                } catch (PrivilegedActionException e) {
2609                    throw (IOException) e.getException();
2610                }
2611                if (stream != null) {
2612                    try {
2613                        bundle = new PropertyResourceBundle(
2614                                new InputStreamReader(stream, StandardCharsets.UTF_8));
2615                    } finally {
2616                        stream.close();
2617                    }
2618                }
2619            } else {
2620                throw new IllegalArgumentException("unknown format: " + format);
2621            }
2622            return bundle;
2623        }
2624
2625        /**
2626         * Returns the time-to-live (TTL) value for resource bundles that
2627         * are loaded under this
2628         * <code>ResourceBundle.Control</code>. Positive time-to-live values
2629         * specify the number of milliseconds a bundle can remain in the
2630         * cache without being validated against the source data from which
2631         * it was constructed. The value 0 indicates that a bundle must be
2632         * validated each time it is retrieved from the cache. {@link
2633         * #TTL_DONT_CACHE} specifies that loaded resource bundles are not
2634         * put in the cache. {@link #TTL_NO_EXPIRATION_CONTROL} specifies
2635         * that loaded resource bundles are put in the cache with no
2636         * expiration control.
2637         *
2638         * <p>The expiration affects only the bundle loading process by the
2639         * <code>ResourceBundle.getBundle</code> factory method.  That is,
2640         * if the factory method finds a resource bundle in the cache that
2641         * has expired, the factory method calls the {@link
2642         * #needsReload(String, Locale, String, ClassLoader, ResourceBundle,
2643         * long) needsReload} method to determine whether the resource
2644         * bundle needs to be reloaded. If <code>needsReload</code> returns
2645         * <code>true</code>, the cached resource bundle instance is removed
2646         * from the cache. Otherwise, the instance stays in the cache,
2647         * updated with the new TTL value returned by this method.
2648         *
2649         * <p>All cached resource bundles are subject to removal from the
2650         * cache due to memory constraints of the runtime environment.
2651         * Returning a large positive value doesn't mean to lock loaded
2652         * resource bundles in the cache.
2653         *
2654         * <p>The default implementation returns {@link #TTL_NO_EXPIRATION_CONTROL}.
2655         *
2656         * @param baseName
2657         *        the base name of the resource bundle for which the
2658         *        expiration value is specified.
2659         * @param locale
2660         *        the locale of the resource bundle for which the
2661         *        expiration value is specified.
2662         * @return the time (0 or a positive millisecond offset from the
2663         *        cached time) to get loaded bundles expired in the cache,
2664         *        {@link #TTL_NO_EXPIRATION_CONTROL} to disable the
2665         *        expiration control, or {@link #TTL_DONT_CACHE} to disable
2666         *        caching.
2667         * @exception NullPointerException
2668         *        if <code>baseName</code> or <code>locale</code> is
2669         *        <code>null</code>
2670         */
2671        public long getTimeToLive(String baseName, Locale locale) {
2672            if (baseName == null || locale == null) {
2673                throw new NullPointerException();
2674            }
2675            return TTL_NO_EXPIRATION_CONTROL;
2676        }
2677
2678        /**
2679         * Determines if the expired <code>bundle</code> in the cache needs
2680         * to be reloaded based on the loading time given by
2681         * <code>loadTime</code> or some other criteria. The method returns
2682         * <code>true</code> if reloading is required; <code>false</code>
2683         * otherwise. <code>loadTime</code> is a millisecond offset since
2684         * the <a href="Calendar.html#Epoch"> <code>Calendar</code>
2685         * Epoch</a>.
2686         *
2687         * The calling <code>ResourceBundle.getBundle</code> factory method
2688         * calls this method on the <code>ResourceBundle.Control</code>
2689         * instance used for its current invocation, not on the instance
2690         * used in the invocation that originally loaded the resource
2691         * bundle.
2692         *
2693         * <p>The default implementation compares <code>loadTime</code> and
2694         * the last modified time of the source data of the resource
2695         * bundle. If it's determined that the source data has been modified
2696         * since <code>loadTime</code>, <code>true</code> is
2697         * returned. Otherwise, <code>false</code> is returned. This
2698         * implementation assumes that the given <code>format</code> is the
2699         * same string as its file suffix if it's not one of the default
2700         * formats, <code>"java.class"</code> or
2701         * <code>"java.properties"</code>.
2702         *
2703         * @param baseName
2704         *        the base bundle name of the resource bundle, a
2705         *        fully qualified class name
2706         * @param locale
2707         *        the locale for which the resource bundle
2708         *        should be instantiated
2709         * @param format
2710         *        the resource bundle format to be loaded
2711         * @param loader
2712         *        the <code>ClassLoader</code> to use to load the bundle
2713         * @param bundle
2714         *        the resource bundle instance that has been expired
2715         *        in the cache
2716         * @param loadTime
2717         *        the time when <code>bundle</code> was loaded and put
2718         *        in the cache
2719         * @return <code>true</code> if the expired bundle needs to be
2720         *        reloaded; <code>false</code> otherwise.
2721         * @exception NullPointerException
2722         *        if <code>baseName</code>, <code>locale</code>,
2723         *        <code>format</code>, <code>loader</code>, or
2724         *        <code>bundle</code> is <code>null</code>
2725         */
2726        public boolean needsReload(String baseName, Locale locale,
2727                                   String format, ClassLoader loader,
2728                                   ResourceBundle bundle, long loadTime) {
2729            if (bundle == null) {
2730                throw new NullPointerException();
2731            }
2732            if (format.equals("java.class") || format.equals("java.properties")) {
2733                format = format.substring(5);
2734            }
2735            boolean result = false;
2736            try {
2737                String resourceName = toResourceName(toBundleName(baseName, locale), format);
2738                URL url = loader.getResource(resourceName);
2739                if (url != null) {
2740                    long lastModified = 0;
2741                    URLConnection connection = url.openConnection();
2742                    if (connection != null) {
2743                        // disable caches to get the correct data
2744                        connection.setUseCaches(false);
2745                        if (connection instanceof JarURLConnection) {
2746                            JarEntry ent = ((JarURLConnection)connection).getJarEntry();
2747                            if (ent != null) {
2748                                lastModified = ent.getTime();
2749                                if (lastModified == -1) {
2750                                    lastModified = 0;
2751                                }
2752                            }
2753                        } else {
2754                            lastModified = connection.getLastModified();
2755                        }
2756                    }
2757                    result = lastModified >= loadTime;
2758                }
2759            } catch (NullPointerException npe) {
2760                throw npe;
2761            } catch (Exception e) {
2762                // ignore other exceptions
2763            }
2764            return result;
2765        }
2766
2767        /**
2768         * Converts the given <code>baseName</code> and <code>locale</code>
2769         * to the bundle name. This method is called from the default
2770         * implementation of the {@link #newBundle(String, Locale, String,
2771         * ClassLoader, boolean) newBundle} and {@link #needsReload(String,
2772         * Locale, String, ClassLoader, ResourceBundle, long) needsReload}
2773         * methods.
2774         *
2775         * <p>This implementation returns the following value:
2776         * <pre>
2777         *     baseName + "_" + language + "_" + script + "_" + country + "_" + variant
2778         * </pre>
2779         * where <code>language</code>, <code>script</code>, <code>country</code>,
2780         * and <code>variant</code> are the language, script, country, and variant
2781         * values of <code>locale</code>, respectively. Final component values that
2782         * are empty Strings are omitted along with the preceding '_'.  When the
2783         * script is empty, the script value is ommitted along with the preceding '_'.
2784         * If all of the values are empty strings, then <code>baseName</code>
2785         * is returned.
2786         *
2787         * <p>For example, if <code>baseName</code> is
2788         * <code>"baseName"</code> and <code>locale</code> is
2789         * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then
2790         * <code>"baseName_ja_&thinsp;_XX"</code> is returned. If the given
2791         * locale is <code>Locale("en")</code>, then
2792         * <code>"baseName_en"</code> is returned.
2793         *
2794         * <p>Overriding this method allows applications to use different
2795         * conventions in the organization and packaging of localized
2796         * resources.
2797         *
2798         * @param baseName
2799         *        the base name of the resource bundle, a fully
2800         *        qualified class name
2801         * @param locale
2802         *        the locale for which a resource bundle should be
2803         *        loaded
2804         * @return the bundle name for the resource bundle
2805         * @exception NullPointerException
2806         *        if <code>baseName</code> or <code>locale</code>
2807         *        is <code>null</code>
2808         */
2809        public String toBundleName(String baseName, Locale locale) {
2810            if (locale == Locale.ROOT) {
2811                return baseName;
2812            }
2813
2814            String language = locale.getLanguage();
2815            String script = locale.getScript();
2816            String country = locale.getCountry();
2817            String variant = locale.getVariant();
2818
2819            if (language == "" && country == "" && variant == "") {
2820                return baseName;
2821            }
2822
2823            StringBuilder sb = new StringBuilder(baseName);
2824            sb.append('_');
2825            if (script != "") {
2826                if (variant != "") {
2827                    sb.append(language).append('_').append(script).append('_').append(country).append('_').append(variant);
2828                } else if (country != "") {
2829                    sb.append(language).append('_').append(script).append('_').append(country);
2830                } else {
2831                    sb.append(language).append('_').append(script);
2832                }
2833            } else {
2834                if (variant != "") {
2835                    sb.append(language).append('_').append(country).append('_').append(variant);
2836                } else if (country != "") {
2837                    sb.append(language).append('_').append(country);
2838                } else {
2839                    sb.append(language);
2840                }
2841            }
2842            return sb.toString();
2843
2844        }
2845
2846        /**
2847         * Converts the given <code>bundleName</code> to the form required
2848         * by the {@link ClassLoader#getResource ClassLoader.getResource}
2849         * method by replacing all occurrences of <code>'.'</code> in
2850         * <code>bundleName</code> with <code>'/'</code> and appending a
2851         * <code>'.'</code> and the given file <code>suffix</code>. For
2852         * example, if <code>bundleName</code> is
2853         * <code>"foo.bar.MyResources_ja_JP"</code> and <code>suffix</code>
2854         * is <code>"properties"</code>, then
2855         * <code>"foo/bar/MyResources_ja_JP.properties"</code> is returned.
2856         *
2857         * @param bundleName
2858         *        the bundle name
2859         * @param suffix
2860         *        the file type suffix
2861         * @return the converted resource name
2862         * @exception NullPointerException
2863         *         if <code>bundleName</code> or <code>suffix</code>
2864         *         is <code>null</code>
2865         */
2866        public final String toResourceName(String bundleName, String suffix) {
2867            StringBuilder sb = new StringBuilder(bundleName.length() + 1 + suffix.length());
2868            sb.append(bundleName.replace('.', '/')).append('.').append(suffix);
2869            return sb.toString();
2870        }
2871    }
2872
2873    private static class SingleFormatControl extends Control {
2874        private static final Control PROPERTIES_ONLY
2875            = new SingleFormatControl(FORMAT_PROPERTIES);
2876
2877        private static final Control CLASS_ONLY
2878            = new SingleFormatControl(FORMAT_CLASS);
2879
2880        private final List<String> formats;
2881
2882        protected SingleFormatControl(List<String> formats) {
2883            this.formats = formats;
2884        }
2885
2886        public List<String> getFormats(String baseName) {
2887            if (baseName == null) {
2888                throw new NullPointerException();
2889            }
2890            return formats;
2891        }
2892    }
2893
2894    private static final class NoFallbackControl extends SingleFormatControl {
2895        private static final Control NO_FALLBACK
2896            = new NoFallbackControl(FORMAT_DEFAULT);
2897
2898        private static final Control PROPERTIES_ONLY_NO_FALLBACK
2899            = new NoFallbackControl(FORMAT_PROPERTIES);
2900
2901        private static final Control CLASS_ONLY_NO_FALLBACK
2902            = new NoFallbackControl(FORMAT_CLASS);
2903
2904        protected NoFallbackControl(List<String> formats) {
2905            super(formats);
2906        }
2907
2908        public Locale getFallbackLocale(String baseName, Locale locale) {
2909            if (baseName == null || locale == null) {
2910                throw new NullPointerException();
2911            }
2912            return null;
2913        }
2914    }
2915}
2916