1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.util;
18
19import java.lang.reflect.Method;
20import java.lang.reflect.InvocationTargetException;
21
22/**
23 * <p>Various utilities for debugging and logging.</p>
24 */
25public class DebugUtils {
26    /** @hide */ public DebugUtils() {}
27
28    /**
29     * <p>Filters objects against the <code>ANDROID_OBJECT_FILTER</code>
30     * environment variable. This environment variable can filter objects
31     * based on their class name and attribute values.</p>
32     *
33     * <p>Here is the syntax for <code>ANDROID_OBJECT_FILTER</code>:</p>
34     *
35     * <p><code>ClassName@attribute1=value1@attribute2=value2...</code></p>
36     *
37     * <p>Examples:</p>
38     * <ul>
39     * <li>Select TextView instances: <code>TextView</code></li>
40     * <li>Select TextView instances of text "Loading" and bottom offset of 22:
41     * <code>TextView@text=Loading.*@bottom=22</code></li>
42     * </ul>
43     *
44     * <p>The class name and the values are regular expressions.</p>
45     *
46     * <p>This class is useful for debugging and logging purpose:</p>
47     * <pre>
48     * if (DEBUG) {
49     *   if (DebugUtils.isObjectSelected(childView) && LOGV_ENABLED) {
50     *     Log.v(TAG, "Object " + childView + " logged!");
51     *   }
52     * }
53     * </pre>
54     *
55     * <p><strong>NOTE</strong>: This method is very expensive as it relies
56     * heavily on regular expressions and reflection. Calls to this method
57     * should always be stripped out of the release binaries and avoided
58     * as much as possible in debug mode.</p>
59     *
60     * @param object any object to match against the ANDROID_OBJECT_FILTER
61     *        environement variable
62     * @return true if object is selected by the ANDROID_OBJECT_FILTER
63     *         environment variable, false otherwise
64     */
65    public static boolean isObjectSelected(Object object) {
66        boolean match = false;
67        String s = System.getenv("ANDROID_OBJECT_FILTER");
68        if (s != null && s.length() > 0) {
69            String[] selectors = s.split("@");
70            // first selector == class name
71            if (object.getClass().getSimpleName().matches(selectors[0])) {
72                // check potential attributes
73                for (int i = 1; i < selectors.length; i++) {
74                    String[] pair = selectors[i].split("=");
75                    Class<?> klass = object.getClass();
76                    try {
77                        Method declaredMethod = null;
78                        Class<?> parent = klass;
79                        do {
80                            declaredMethod = parent.getDeclaredMethod("get" +
81                                    pair[0].substring(0, 1).toUpperCase() +
82                                    pair[0].substring(1),
83                                    (Class[]) null);
84                        } while ((parent = klass.getSuperclass()) != null &&
85                                declaredMethod == null);
86
87                        if (declaredMethod != null) {
88                            Object value = declaredMethod
89                                    .invoke(object, (Object[])null);
90                            match |= (value != null ?
91                                    value.toString() : "null").matches(pair[1]);
92                        }
93                    } catch (NoSuchMethodException e) {
94                        e.printStackTrace();
95                    } catch (IllegalAccessException e) {
96                        e.printStackTrace();
97                    } catch (InvocationTargetException e) {
98                        e.printStackTrace();
99                    }
100                }
101            }
102        }
103        return match;
104    }
105
106    /** @hide */
107    public static void buildShortClassTag(Object cls, StringBuilder out) {
108        if (cls == null) {
109            out.append("null");
110        } else {
111            String simpleName = cls.getClass().getSimpleName();
112            if (simpleName == null || simpleName.isEmpty()) {
113                simpleName = cls.getClass().getName();
114                int end = simpleName.lastIndexOf('.');
115                if (end > 0) {
116                    simpleName = simpleName.substring(end+1);
117                }
118            }
119            out.append(simpleName);
120            out.append('{');
121            out.append(Integer.toHexString(System.identityHashCode(cls)));
122        }
123    }
124
125}
126