1/*
2 * Copyright (C) 2010 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.nfc;
18
19import android.annotation.RequiresPermission;
20import android.annotation.SdkConstant;
21import android.annotation.SdkConstant.SdkConstantType;
22import android.annotation.SystemApi;
23import android.app.Activity;
24import android.app.ActivityThread;
25import android.app.OnActivityPausedListener;
26import android.app.PendingIntent;
27import android.content.Context;
28import android.content.IntentFilter;
29import android.content.pm.IPackageManager;
30import android.content.pm.PackageManager;
31import android.net.Uri;
32import android.nfc.tech.MifareClassic;
33import android.nfc.tech.Ndef;
34import android.nfc.tech.NfcA;
35import android.nfc.tech.NfcF;
36import android.os.Bundle;
37import android.os.Handler;
38import android.os.IBinder;
39import android.os.RemoteException;
40import android.os.ServiceManager;
41import android.util.Log;
42
43import java.io.IOException;
44import java.util.HashMap;
45
46/**
47 * Represents the local NFC adapter.
48 * <p>
49 * Use the helper {@link #getDefaultAdapter(Context)} to get the default NFC
50 * adapter for this Android device.
51 *
52 * <div class="special reference">
53 * <h3>Developer Guides</h3>
54 * <p>For more information about using NFC, read the
55 * <a href="{@docRoot}guide/topics/nfc/index.html">Near Field Communication</a> developer guide.</p>
56 * <p>To perform basic file sharing between devices, read
57 * <a href="{@docRoot}training/beam-files/index.html">Sharing Files with NFC</a>.
58 * </div>
59 */
60public final class NfcAdapter {
61    static final String TAG = "NFC";
62
63    /**
64     * Intent to start an activity when a tag with NDEF payload is discovered.
65     *
66     * <p>The system inspects the first {@link NdefRecord} in the first {@link NdefMessage} and
67     * looks for a URI, SmartPoster, or MIME record. If a URI or SmartPoster record is found the
68     * intent will contain the URI in its data field. If a MIME record is found the intent will
69     * contain the MIME type in its type field. This allows activities to register
70     * {@link IntentFilter}s targeting specific content on tags. Activities should register the
71     * most specific intent filters possible to avoid the activity chooser dialog, which can
72     * disrupt the interaction with the tag as the user interacts with the screen.
73     *
74     * <p>If the tag has an NDEF payload this intent is started before
75     * {@link #ACTION_TECH_DISCOVERED}. If any activities respond to this intent neither
76     * {@link #ACTION_TECH_DISCOVERED} or {@link #ACTION_TAG_DISCOVERED} will be started.
77     *
78     * <p>The MIME type or data URI of this intent are normalized before dispatch -
79     * so that MIME, URI scheme and URI host are always lower-case.
80     */
81    @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
82    public static final String ACTION_NDEF_DISCOVERED = "android.nfc.action.NDEF_DISCOVERED";
83
84    /**
85     * Intent to start an activity when a tag is discovered and activities are registered for the
86     * specific technologies on the tag.
87     *
88     * <p>To receive this intent an activity must include an intent filter
89     * for this action and specify the desired tech types in a
90     * manifest <code>meta-data</code> entry. Here is an example manfiest entry:
91     * <pre>
92     * &lt;activity android:name=".nfc.TechFilter" android:label="NFC/TechFilter"&gt;
93     *     &lt;!-- Add a technology filter --&gt;
94     *     &lt;intent-filter&gt;
95     *         &lt;action android:name="android.nfc.action.TECH_DISCOVERED" /&gt;
96     *     &lt;/intent-filter&gt;
97     *
98     *     &lt;meta-data android:name="android.nfc.action.TECH_DISCOVERED"
99     *         android:resource="@xml/filter_nfc"
100     *     /&gt;
101     * &lt;/activity&gt;</pre>
102     *
103     * <p>The meta-data XML file should contain one or more <code>tech-list</code> entries
104     * each consisting or one or more <code>tech</code> entries. The <code>tech</code> entries refer
105     * to the qualified class name implementing the technology, for example "android.nfc.tech.NfcA".
106     *
107     * <p>A tag matches if any of the
108     * <code>tech-list</code> sets is a subset of {@link Tag#getTechList() Tag.getTechList()}. Each
109     * of the <code>tech-list</code>s is considered independently and the
110     * activity is considered a match is any single <code>tech-list</code> matches the tag that was
111     * discovered. This provides AND and OR semantics for filtering desired techs. Here is an
112     * example that will match any tag using {@link NfcF} or any tag using {@link NfcA},
113     * {@link MifareClassic}, and {@link Ndef}:
114     *
115     * <pre>
116     * &lt;resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2"&gt;
117     *     &lt;!-- capture anything using NfcF --&gt;
118     *     &lt;tech-list&gt;
119     *         &lt;tech&gt;android.nfc.tech.NfcF&lt;/tech&gt;
120     *     &lt;/tech-list&gt;
121     *
122     *     &lt;!-- OR --&gt;
123     *
124     *     &lt;!-- capture all MIFARE Classics with NDEF payloads --&gt;
125     *     &lt;tech-list&gt;
126     *         &lt;tech&gt;android.nfc.tech.NfcA&lt;/tech&gt;
127     *         &lt;tech&gt;android.nfc.tech.MifareClassic&lt;/tech&gt;
128     *         &lt;tech&gt;android.nfc.tech.Ndef&lt;/tech&gt;
129     *     &lt;/tech-list&gt;
130     * &lt;/resources&gt;</pre>
131     *
132     * <p>This intent is started after {@link #ACTION_NDEF_DISCOVERED} and before
133     * {@link #ACTION_TAG_DISCOVERED}. If any activities respond to {@link #ACTION_NDEF_DISCOVERED}
134     * this intent will not be started. If any activities respond to this intent
135     * {@link #ACTION_TAG_DISCOVERED} will not be started.
136     */
137    @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
138    public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED";
139
140    /**
141     * Intent to start an activity when a tag is discovered.
142     *
143     * <p>This intent will not be started when a tag is discovered if any activities respond to
144     * {@link #ACTION_NDEF_DISCOVERED} or {@link #ACTION_TECH_DISCOVERED} for the current tag.
145     */
146    @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
147    public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED";
148
149    /**
150     * Broadcast Action: Intent to notify an application that an transaction event has occurred
151     * on the Secure Element.
152     *
153     * <p>This intent will only be sent if the application has requested permission for
154     * {@link android.Manifest.permission#NFC_TRANSACTION_EVENT} and if the application has the
155     * necessary access to Secure Element which witnessed the particular event.
156     */
157    @RequiresPermission(android.Manifest.permission.NFC_TRANSACTION_EVENT)
158    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
159    public static final String ACTION_TRANSACTION_DETECTED =
160            "android.nfc.action.TRANSACTION_DETECTED";
161
162    /**
163     * Broadcast to only the activity that handles ACTION_TAG_DISCOVERED
164     * @hide
165     */
166    public static final String ACTION_TAG_LEFT_FIELD = "android.nfc.action.TAG_LOST";
167
168    /**
169     * Mandatory extra containing the {@link Tag} that was discovered for the
170     * {@link #ACTION_NDEF_DISCOVERED}, {@link #ACTION_TECH_DISCOVERED}, and
171     * {@link #ACTION_TAG_DISCOVERED} intents.
172     */
173    public static final String EXTRA_TAG = "android.nfc.extra.TAG";
174
175    /**
176     * Extra containing an array of {@link NdefMessage} present on the discovered tag.<p>
177     * This extra is mandatory for {@link #ACTION_NDEF_DISCOVERED} intents,
178     * and optional for {@link #ACTION_TECH_DISCOVERED}, and
179     * {@link #ACTION_TAG_DISCOVERED} intents.<p>
180     * When this extra is present there will always be at least one
181     * {@link NdefMessage} element. Most NDEF tags have only one NDEF message,
182     * but we use an array for future compatibility.
183     */
184    public static final String EXTRA_NDEF_MESSAGES = "android.nfc.extra.NDEF_MESSAGES";
185
186    /**
187     * Optional extra containing a byte array containing the ID of the discovered tag for
188     * the {@link #ACTION_NDEF_DISCOVERED}, {@link #ACTION_TECH_DISCOVERED}, and
189     * {@link #ACTION_TAG_DISCOVERED} intents.
190     */
191    public static final String EXTRA_ID = "android.nfc.extra.ID";
192
193    /**
194     * Broadcast Action: The state of the local NFC adapter has been
195     * changed.
196     * <p>For example, NFC has been turned on or off.
197     * <p>Always contains the extra field {@link #EXTRA_ADAPTER_STATE}
198     */
199    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
200    public static final String ACTION_ADAPTER_STATE_CHANGED =
201            "android.nfc.action.ADAPTER_STATE_CHANGED";
202
203    /**
204     * Used as an int extra field in {@link #ACTION_ADAPTER_STATE_CHANGED}
205     * intents to request the current power state. Possible values are:
206     * {@link #STATE_OFF},
207     * {@link #STATE_TURNING_ON},
208     * {@link #STATE_ON},
209     * {@link #STATE_TURNING_OFF},
210     */
211    public static final String EXTRA_ADAPTER_STATE = "android.nfc.extra.ADAPTER_STATE";
212
213    /**
214     * Mandatory byte[] extra field in {@link #ACTION_TRANSACTION_DETECTED}
215     */
216    public static final String EXTRA_AID = "android.nfc.extra.AID";
217
218    /**
219     * Optional byte[] extra field in {@link #ACTION_TRANSACTION_DETECTED}
220     */
221    public static final String EXTRA_DATA = "android.nfc.extra.DATA";
222
223    /**
224     * Mandatory String extra field in {@link #ACTION_TRANSACTION_DETECTED}
225     * Indicates the Secure Element on which the transaction occurred.
226     * eSE1...eSEn for Embedded Secure Elements, SIM1...SIMn for UICC, etc.
227     */
228    public static final String EXTRA_SECURE_ELEMENT_NAME = "android.nfc.extra.SECURE_ELEMENT_NAME";
229
230    public static final int STATE_OFF = 1;
231    public static final int STATE_TURNING_ON = 2;
232    public static final int STATE_ON = 3;
233    public static final int STATE_TURNING_OFF = 4;
234
235    /**
236     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
237     * <p>
238     * Setting this flag enables polling for Nfc-A technology.
239     */
240    public static final int FLAG_READER_NFC_A = 0x1;
241
242    /**
243     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
244     * <p>
245     * Setting this flag enables polling for Nfc-B technology.
246     */
247    public static final int FLAG_READER_NFC_B = 0x2;
248
249    /**
250     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
251     * <p>
252     * Setting this flag enables polling for Nfc-F technology.
253     */
254    public static final int FLAG_READER_NFC_F = 0x4;
255
256    /**
257     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
258     * <p>
259     * Setting this flag enables polling for Nfc-V (ISO15693) technology.
260     */
261    public static final int FLAG_READER_NFC_V = 0x8;
262
263    /**
264     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
265     * <p>
266     * Setting this flag enables polling for NfcBarcode technology.
267     */
268    public static final int FLAG_READER_NFC_BARCODE = 0x10;
269
270    /**
271     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
272     * <p>
273     * Setting this flag allows the caller to prevent the
274     * platform from performing an NDEF check on the tags it
275     * finds.
276     */
277    public static final int FLAG_READER_SKIP_NDEF_CHECK = 0x80;
278
279    /**
280     * Flag for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
281     * <p>
282     * Setting this flag allows the caller to prevent the
283     * platform from playing sounds when it discovers a tag.
284     */
285    public static final int FLAG_READER_NO_PLATFORM_SOUNDS = 0x100;
286
287    /**
288     * Int Extra for use with {@link #enableReaderMode(Activity, ReaderCallback, int, Bundle)}.
289     * <p>
290     * Setting this integer extra allows the calling application to specify
291     * the delay that the platform will use for performing presence checks
292     * on any discovered tag.
293     */
294    public static final String EXTRA_READER_PRESENCE_CHECK_DELAY = "presence";
295
296    /** @hide */
297    @SystemApi
298    public static final int FLAG_NDEF_PUSH_NO_CONFIRM = 0x1;
299
300    /** @hide */
301    public static final String ACTION_HANDOVER_TRANSFER_STARTED =
302            "android.nfc.action.HANDOVER_TRANSFER_STARTED";
303
304    /** @hide */
305    public static final String ACTION_HANDOVER_TRANSFER_DONE =
306            "android.nfc.action.HANDOVER_TRANSFER_DONE";
307
308    /** @hide */
309    public static final String EXTRA_HANDOVER_TRANSFER_STATUS =
310            "android.nfc.extra.HANDOVER_TRANSFER_STATUS";
311
312    /** @hide */
313    public static final int HANDOVER_TRANSFER_STATUS_SUCCESS = 0;
314    /** @hide */
315    public static final int HANDOVER_TRANSFER_STATUS_FAILURE = 1;
316
317    /** @hide */
318    public static final String EXTRA_HANDOVER_TRANSFER_URI =
319            "android.nfc.extra.HANDOVER_TRANSFER_URI";
320
321    // Guarded by NfcAdapter.class
322    static boolean sIsInitialized = false;
323    static boolean sHasNfcFeature;
324
325    // Final after first constructor, except for
326    // attemptDeadServiceRecovery() when NFC crashes - we accept a best effort
327    // recovery
328    static INfcAdapter sService;
329    static INfcTag sTagService;
330    static INfcCardEmulation sCardEmulationService;
331    static INfcFCardEmulation sNfcFCardEmulationService;
332
333    /**
334     * The NfcAdapter object for each application context.
335     * There is a 1-1 relationship between application context and
336     * NfcAdapter object.
337     */
338    static HashMap<Context, NfcAdapter> sNfcAdapters = new HashMap(); //guard by NfcAdapter.class
339
340    /**
341     * NfcAdapter used with a null context. This ctor was deprecated but we have
342     * to support it for backwards compatibility. New methods that require context
343     * might throw when called on the null-context NfcAdapter.
344     */
345    static NfcAdapter sNullContextNfcAdapter;  // protected by NfcAdapter.class
346
347    final NfcActivityManager mNfcActivityManager;
348    final Context mContext;
349    final HashMap<NfcUnlockHandler, INfcUnlockHandler> mNfcUnlockHandlers;
350    final Object mLock;
351
352    ITagRemovedCallback mTagRemovedListener; // protected by mLock
353
354    /**
355     * A callback to be invoked when the system finds a tag while the foreground activity is
356     * operating in reader mode.
357     * <p>Register your {@code ReaderCallback} implementation with {@link
358     * NfcAdapter#enableReaderMode} and disable it with {@link
359     * NfcAdapter#disableReaderMode}.
360     * @see NfcAdapter#enableReaderMode
361     */
362    public interface ReaderCallback {
363        public void onTagDiscovered(Tag tag);
364    }
365
366    /**
367     * A callback to be invoked when the system successfully delivers your {@link NdefMessage}
368     * to another device.
369     * @see #setOnNdefPushCompleteCallback
370     */
371    public interface OnNdefPushCompleteCallback {
372        /**
373         * Called on successful NDEF push.
374         *
375         * <p>This callback is usually made on a binder thread (not the UI thread).
376         *
377         * @param event {@link NfcEvent} with the {@link NfcEvent#nfcAdapter} field set
378         * @see #setNdefPushMessageCallback
379         */
380        public void onNdefPushComplete(NfcEvent event);
381    }
382
383    /**
384     * A callback to be invoked when another NFC device capable of NDEF push (Android Beam)
385     * is within range.
386     * <p>Implement this interface and pass it to {@link
387     * NfcAdapter#setNdefPushMessageCallback setNdefPushMessageCallback()} in order to create an
388     * {@link NdefMessage} at the moment that another device is within range for NFC. Using this
389     * callback allows you to create a message with data that might vary based on the
390     * content currently visible to the user. Alternatively, you can call {@link
391     * #setNdefPushMessage setNdefPushMessage()} if the {@link NdefMessage} always contains the
392     * same data.
393     */
394    public interface CreateNdefMessageCallback {
395        /**
396         * Called to provide a {@link NdefMessage} to push.
397         *
398         * <p>This callback is usually made on a binder thread (not the UI thread).
399         *
400         * <p>Called when this device is in range of another device
401         * that might support NDEF push. It allows the application to
402         * create the NDEF message only when it is required.
403         *
404         * <p>NDEF push cannot occur until this method returns, so do not
405         * block for too long.
406         *
407         * <p>The Android operating system will usually show a system UI
408         * on top of your activity during this time, so do not try to request
409         * input from the user to complete the callback, or provide custom NDEF
410         * push UI. The user probably will not see it.
411         *
412         * @param event {@link NfcEvent} with the {@link NfcEvent#nfcAdapter} field set
413         * @return NDEF message to push, or null to not provide a message
414         */
415        public NdefMessage createNdefMessage(NfcEvent event);
416    }
417
418
419    // TODO javadoc
420    public interface CreateBeamUrisCallback {
421        public Uri[] createBeamUris(NfcEvent event);
422    }
423
424    /**
425     * A callback that is invoked when a tag is removed from the field.
426     * @see NfcAdapter#ignore
427     */
428    public interface OnTagRemovedListener {
429        void onTagRemoved();
430    }
431
432    /**
433     * A callback to be invoked when an application has registered as a
434     * handler to unlock the device given an NFC tag at the lockscreen.
435     * @hide
436     */
437    @SystemApi
438    public interface NfcUnlockHandler {
439        /**
440         * Called at the lock screen to attempt to unlock the device with the given tag.
441         * @param tag the detected tag, to be used to unlock the device
442         * @return true if the device was successfully unlocked
443         */
444        public boolean onUnlockAttempted(Tag tag);
445    }
446
447
448    /**
449     * Helper to check if this device has FEATURE_NFC, but without using
450     * a context.
451     * Equivalent to
452     * context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_NFC)
453     */
454    private static boolean hasNfcFeature() {
455        IPackageManager pm = ActivityThread.getPackageManager();
456        if (pm == null) {
457            Log.e(TAG, "Cannot get package manager, assuming no NFC feature");
458            return false;
459        }
460        try {
461            return pm.hasSystemFeature(PackageManager.FEATURE_NFC, 0);
462        } catch (RemoteException e) {
463            Log.e(TAG, "Package manager query failed, assuming no NFC feature", e);
464            return false;
465        }
466    }
467
468    /**
469     * Helper to check if this device is NFC HCE capable, by checking for
470     * FEATURE_NFC_HOST_CARD_EMULATION and/or FEATURE_NFC_HOST_CARD_EMULATION_NFCF,
471     * but without using a context.
472     */
473    private static boolean hasNfcHceFeature() {
474        IPackageManager pm = ActivityThread.getPackageManager();
475        if (pm == null) {
476            Log.e(TAG, "Cannot get package manager, assuming no NFC feature");
477            return false;
478        }
479        try {
480            return pm.hasSystemFeature(PackageManager.FEATURE_NFC_HOST_CARD_EMULATION, 0)
481                || pm.hasSystemFeature(PackageManager.FEATURE_NFC_HOST_CARD_EMULATION_NFCF, 0);
482        } catch (RemoteException e) {
483            Log.e(TAG, "Package manager query failed, assuming no NFC feature", e);
484            return false;
485        }
486    }
487
488    /**
489     * Returns the NfcAdapter for application context,
490     * or throws if NFC is not available.
491     * @hide
492     */
493    public static synchronized NfcAdapter getNfcAdapter(Context context) {
494        if (!sIsInitialized) {
495            sHasNfcFeature = hasNfcFeature();
496            boolean hasHceFeature = hasNfcHceFeature();
497            /* is this device meant to have NFC */
498            if (!sHasNfcFeature && !hasHceFeature) {
499                Log.v(TAG, "this device does not have NFC support");
500                throw new UnsupportedOperationException();
501            }
502            sService = getServiceInterface();
503            if (sService == null) {
504                Log.e(TAG, "could not retrieve NFC service");
505                throw new UnsupportedOperationException();
506            }
507            if (sHasNfcFeature) {
508                try {
509                    sTagService = sService.getNfcTagInterface();
510                } catch (RemoteException e) {
511                    Log.e(TAG, "could not retrieve NFC Tag service");
512                    throw new UnsupportedOperationException();
513                }
514            }
515            if (hasHceFeature) {
516                try {
517                    sNfcFCardEmulationService = sService.getNfcFCardEmulationInterface();
518                } catch (RemoteException e) {
519                    Log.e(TAG, "could not retrieve NFC-F card emulation service");
520                    throw new UnsupportedOperationException();
521                }
522                try {
523                    sCardEmulationService = sService.getNfcCardEmulationInterface();
524                } catch (RemoteException e) {
525                    Log.e(TAG, "could not retrieve card emulation service");
526                    throw new UnsupportedOperationException();
527                }
528            }
529
530            sIsInitialized = true;
531        }
532        if (context == null) {
533            if (sNullContextNfcAdapter == null) {
534                sNullContextNfcAdapter = new NfcAdapter(null);
535            }
536            return sNullContextNfcAdapter;
537        }
538        NfcAdapter adapter = sNfcAdapters.get(context);
539        if (adapter == null) {
540            adapter = new NfcAdapter(context);
541            sNfcAdapters.put(context, adapter);
542        }
543        return adapter;
544    }
545
546    /** get handle to NFC service interface */
547    private static INfcAdapter getServiceInterface() {
548        /* get a handle to NFC service */
549        IBinder b = ServiceManager.getService("nfc");
550        if (b == null) {
551            return null;
552        }
553        return INfcAdapter.Stub.asInterface(b);
554    }
555
556    /**
557     * Helper to get the default NFC Adapter.
558     * <p>
559     * Most Android devices will only have one NFC Adapter (NFC Controller).
560     * <p>
561     * This helper is the equivalent of:
562     * <pre>
563     * NfcManager manager = (NfcManager) context.getSystemService(Context.NFC_SERVICE);
564     * NfcAdapter adapter = manager.getDefaultAdapter();</pre>
565     * @param context the calling application's context
566     *
567     * @return the default NFC adapter, or null if no NFC adapter exists
568     */
569    public static NfcAdapter getDefaultAdapter(Context context) {
570        if (context == null) {
571            throw new IllegalArgumentException("context cannot be null");
572        }
573        context = context.getApplicationContext();
574        if (context == null) {
575            throw new IllegalArgumentException(
576                    "context not associated with any application (using a mock context?)");
577        }
578        /* use getSystemService() for consistency */
579        NfcManager manager = (NfcManager) context.getSystemService(Context.NFC_SERVICE);
580        if (manager == null) {
581            // NFC not available
582            return null;
583        }
584        return manager.getDefaultAdapter();
585    }
586
587    /**
588     * Legacy NfcAdapter getter, always use {@link #getDefaultAdapter(Context)} instead.<p>
589     * This method was deprecated at API level 10 (Gingerbread MR1) because a context is required
590     * for many NFC API methods. Those methods will fail when called on an NfcAdapter
591     * object created from this method.<p>
592     * @deprecated use {@link #getDefaultAdapter(Context)}
593     * @hide
594     */
595    @Deprecated
596    public static NfcAdapter getDefaultAdapter() {
597        // introduced in API version 9 (GB 2.3)
598        // deprecated in API version 10 (GB 2.3.3)
599        // removed from public API in version 16 (ICS MR2)
600        // should maintain as a hidden API for binary compatibility for a little longer
601        Log.w(TAG, "WARNING: NfcAdapter.getDefaultAdapter() is deprecated, use " +
602                "NfcAdapter.getDefaultAdapter(Context) instead", new Exception());
603
604        return NfcAdapter.getNfcAdapter(null);
605    }
606
607    NfcAdapter(Context context) {
608        mContext = context;
609        mNfcActivityManager = new NfcActivityManager(this);
610        mNfcUnlockHandlers = new HashMap<NfcUnlockHandler, INfcUnlockHandler>();
611        mTagRemovedListener = null;
612        mLock = new Object();
613    }
614
615    /**
616     * @hide
617     */
618    public Context getContext() {
619        return mContext;
620    }
621
622    /**
623     * Returns the binder interface to the service.
624     * @hide
625     */
626    public INfcAdapter getService() {
627        isEnabled();  // NOP call to recover sService if it is stale
628        return sService;
629    }
630
631    /**
632     * Returns the binder interface to the tag service.
633     * @hide
634     */
635    public INfcTag getTagService() {
636        isEnabled();  // NOP call to recover sTagService if it is stale
637        return sTagService;
638    }
639
640    /**
641     * Returns the binder interface to the card emulation service.
642     * @hide
643     */
644    public INfcCardEmulation getCardEmulationService() {
645        isEnabled();
646        return sCardEmulationService;
647    }
648
649    /**
650     * Returns the binder interface to the NFC-F card emulation service.
651     * @hide
652     */
653    public INfcFCardEmulation getNfcFCardEmulationService() {
654        isEnabled();
655        return sNfcFCardEmulationService;
656    }
657
658    /**
659     * Returns the binder interface to the NFC-DTA test interface.
660     * @hide
661     */
662    public INfcDta getNfcDtaInterface() {
663        if (mContext == null) {
664            throw new UnsupportedOperationException("You need a context on NfcAdapter to use the "
665                    + " NFC extras APIs");
666        }
667        try {
668            return sService.getNfcDtaInterface(mContext.getPackageName());
669        } catch (RemoteException e) {
670            attemptDeadServiceRecovery(e);
671            return null;
672        }
673    }
674
675    /**
676     * NFC service dead - attempt best effort recovery
677     * @hide
678     */
679    public void attemptDeadServiceRecovery(Exception e) {
680        Log.e(TAG, "NFC service dead - attempting to recover", e);
681        INfcAdapter service = getServiceInterface();
682        if (service == null) {
683            Log.e(TAG, "could not retrieve NFC service during service recovery");
684            // nothing more can be done now, sService is still stale, we'll hit
685            // this recovery path again later
686            return;
687        }
688        // assigning to sService is not thread-safe, but this is best-effort code
689        // and on a well-behaved system should never happen
690        sService = service;
691        try {
692            sTagService = service.getNfcTagInterface();
693        } catch (RemoteException ee) {
694            Log.e(TAG, "could not retrieve NFC tag service during service recovery");
695            // nothing more can be done now, sService is still stale, we'll hit
696            // this recovery path again later
697            return;
698        }
699
700        try {
701            sCardEmulationService = service.getNfcCardEmulationInterface();
702        } catch (RemoteException ee) {
703            Log.e(TAG, "could not retrieve NFC card emulation service during service recovery");
704        }
705
706        try {
707            sNfcFCardEmulationService = service.getNfcFCardEmulationInterface();
708        } catch (RemoteException ee) {
709            Log.e(TAG, "could not retrieve NFC-F card emulation service during service recovery");
710        }
711
712        return;
713    }
714
715    /**
716     * Return true if this NFC Adapter has any features enabled.
717     *
718     * <p>If this method returns false, the NFC hardware is guaranteed not to
719     * generate or respond to any NFC communication over its NFC radio.
720     * <p>Applications can use this to check if NFC is enabled. Applications
721     * can request Settings UI allowing the user to toggle NFC using:
722     * <p><pre>startActivity(new Intent(Settings.ACTION_NFC_SETTINGS))</pre>
723     *
724     * @see android.provider.Settings#ACTION_NFC_SETTINGS
725     * @return true if this NFC Adapter has any features enabled
726     */
727    public boolean isEnabled() {
728        try {
729            return sService.getState() == STATE_ON;
730        } catch (RemoteException e) {
731            attemptDeadServiceRecovery(e);
732            return false;
733        }
734    }
735
736    /**
737     * Return the state of this NFC Adapter.
738     *
739     * <p>Returns one of {@link #STATE_ON}, {@link #STATE_TURNING_ON},
740     * {@link #STATE_OFF}, {@link #STATE_TURNING_OFF}.
741     *
742     * <p>{@link #isEnabled()} is equivalent to
743     * <code>{@link #getAdapterState()} == {@link #STATE_ON}</code>
744     *
745     * @return the current state of this NFC adapter
746     *
747     * @hide
748     */
749    public int getAdapterState() {
750        try {
751            return sService.getState();
752        } catch (RemoteException e) {
753            attemptDeadServiceRecovery(e);
754            return NfcAdapter.STATE_OFF;
755        }
756    }
757
758    /**
759     * Enable NFC hardware.
760     *
761     * <p>This call is asynchronous. Listen for
762     * {@link #ACTION_ADAPTER_STATE_CHANGED} broadcasts to find out when the
763     * operation is complete.
764     *
765     * <p>If this returns true, then either NFC is already on, or
766     * a {@link #ACTION_ADAPTER_STATE_CHANGED} broadcast will be sent
767     * to indicate a state transition. If this returns false, then
768     * there is some problem that prevents an attempt to turn
769     * NFC on (for example we are in airplane mode and NFC is not
770     * toggleable in airplane mode on this platform).
771     *
772     * @hide
773     */
774    @SystemApi
775    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
776    public boolean enable() {
777        try {
778            return sService.enable();
779        } catch (RemoteException e) {
780            attemptDeadServiceRecovery(e);
781            return false;
782        }
783    }
784
785    /**
786     * Disable NFC hardware.
787     *
788     * <p>No NFC features will work after this call, and the hardware
789     * will not perform or respond to any NFC communication.
790     *
791     * <p>This call is asynchronous. Listen for
792     * {@link #ACTION_ADAPTER_STATE_CHANGED} broadcasts to find out when the
793     * operation is complete.
794     *
795     * <p>If this returns true, then either NFC is already off, or
796     * a {@link #ACTION_ADAPTER_STATE_CHANGED} broadcast will be sent
797     * to indicate a state transition. If this returns false, then
798     * there is some problem that prevents an attempt to turn
799     * NFC off.
800     *
801     * @hide
802     */
803    @SystemApi
804    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
805    public boolean disable() {
806        try {
807            return sService.disable(true);
808        } catch (RemoteException e) {
809            attemptDeadServiceRecovery(e);
810            return false;
811        }
812    }
813
814    /**
815     * Disable NFC hardware.
816     * @hide
817    */
818    @SystemApi
819    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
820    public boolean disable(boolean persist) {
821        try {
822            return sService.disable(persist);
823        } catch (RemoteException e) {
824            attemptDeadServiceRecovery(e);
825            return false;
826        }
827    }
828
829    /**
830     * Pauses polling for a {@code timeoutInMs} millis. If polling must be resumed before timeout,
831     * use {@link #resumePolling()}.
832     * @hide
833     */
834    public void pausePolling(int timeoutInMs) {
835        try {
836            sService.pausePolling(timeoutInMs);
837        } catch (RemoteException e) {
838            attemptDeadServiceRecovery(e);
839        }
840    }
841
842    /**
843     * Resumes default polling for the current device state if polling is paused. Calling
844     * this while polling is not paused is a no-op.
845     *
846     * @hide
847     */
848    public void resumePolling() {
849        try {
850            sService.resumePolling();
851        } catch (RemoteException e) {
852            attemptDeadServiceRecovery(e);
853        }
854    }
855
856    /**
857     * Set one or more {@link Uri}s to send using Android Beam (TM). Every
858     * Uri you provide must have either scheme 'file' or scheme 'content'.
859     *
860     * <p>For the data provided through this method, Android Beam tries to
861     * switch to alternate transports such as Bluetooth to achieve a fast
862     * transfer speed. Hence this method is very suitable
863     * for transferring large files such as pictures or songs.
864     *
865     * <p>The receiving side will store the content of each Uri in
866     * a file and present a notification to the user to open the file
867     * with a {@link android.content.Intent} with action
868     * {@link android.content.Intent#ACTION_VIEW}.
869     * If multiple URIs are sent, the {@link android.content.Intent} will refer
870     * to the first of the stored files.
871     *
872     * <p>This method may be called at any time before {@link Activity#onDestroy},
873     * but the URI(s) are only made available for Android Beam when the
874     * specified activity(s) are in resumed (foreground) state. The recommended
875     * approach is to call this method during your Activity's
876     * {@link Activity#onCreate} - see sample
877     * code below. This method does not immediately perform any I/O or blocking work,
878     * so is safe to call on your main thread.
879     *
880     * <p>{@link #setBeamPushUris} and {@link #setBeamPushUrisCallback}
881     * have priority over both {@link #setNdefPushMessage} and
882     * {@link #setNdefPushMessageCallback}.
883     *
884     * <p>If {@link #setBeamPushUris} is called with a null Uri array,
885     * and/or {@link #setBeamPushUrisCallback} is called with a null callback,
886     * then the Uri push will be completely disabled for the specified activity(s).
887     *
888     * <p>Code example:
889     * <pre>
890     * protected void onCreate(Bundle savedInstanceState) {
891     *     super.onCreate(savedInstanceState);
892     *     NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
893     *     if (nfcAdapter == null) return;  // NFC not available on this device
894     *     nfcAdapter.setBeamPushUris(new Uri[] {uri1, uri2}, this);
895     * }</pre>
896     * And that is it. Only one call per activity is necessary. The Android
897     * OS will automatically release its references to the Uri(s) and the
898     * Activity object when it is destroyed if you follow this pattern.
899     *
900     * <p>If your Activity wants to dynamically supply Uri(s),
901     * then set a callback using {@link #setBeamPushUrisCallback} instead
902     * of using this method.
903     *
904     * <p class="note">Do not pass in an Activity that has already been through
905     * {@link Activity#onDestroy}. This is guaranteed if you call this API
906     * during {@link Activity#onCreate}.
907     *
908     * <p class="note">If this device does not support alternate transports
909     * such as Bluetooth or WiFI, calling this method does nothing.
910     *
911     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
912     *
913     * @param uris an array of Uri(s) to push over Android Beam
914     * @param activity activity for which the Uri(s) will be pushed
915     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
916     */
917    public void setBeamPushUris(Uri[] uris, Activity activity) {
918        synchronized (NfcAdapter.class) {
919            if (!sHasNfcFeature) {
920                throw new UnsupportedOperationException();
921            }
922        }
923        if (activity == null) {
924            throw new NullPointerException("activity cannot be null");
925        }
926        if (uris != null) {
927            for (Uri uri : uris) {
928                if (uri == null) throw new NullPointerException("Uri not " +
929                        "allowed to be null");
930                String scheme = uri.getScheme();
931                if (scheme == null || (!scheme.equalsIgnoreCase("file") &&
932                        !scheme.equalsIgnoreCase("content"))) {
933                    throw new IllegalArgumentException("URI needs to have " +
934                            "either scheme file or scheme content");
935                }
936            }
937        }
938        mNfcActivityManager.setNdefPushContentUri(activity, uris);
939    }
940
941    /**
942     * Set a callback that will dynamically generate one or more {@link Uri}s
943     * to send using Android Beam (TM). Every Uri the callback provides
944     * must have either scheme 'file' or scheme 'content'.
945     *
946     * <p>For the data provided through this callback, Android Beam tries to
947     * switch to alternate transports such as Bluetooth to achieve a fast
948     * transfer speed. Hence this method is very suitable
949     * for transferring large files such as pictures or songs.
950     *
951     * <p>The receiving side will store the content of each Uri in
952     * a file and present a notification to the user to open the file
953     * with a {@link android.content.Intent} with action
954     * {@link android.content.Intent#ACTION_VIEW}.
955     * If multiple URIs are sent, the {@link android.content.Intent} will refer
956     * to the first of the stored files.
957     *
958     * <p>This method may be called at any time before {@link Activity#onDestroy},
959     * but the URI(s) are only made available for Android Beam when the
960     * specified activity(s) are in resumed (foreground) state. The recommended
961     * approach is to call this method during your Activity's
962     * {@link Activity#onCreate} - see sample
963     * code below. This method does not immediately perform any I/O or blocking work,
964     * so is safe to call on your main thread.
965     *
966     * <p>{@link #setBeamPushUris} and {@link #setBeamPushUrisCallback}
967     * have priority over both {@link #setNdefPushMessage} and
968     * {@link #setNdefPushMessageCallback}.
969     *
970     * <p>If {@link #setBeamPushUris} is called with a null Uri array,
971     * and/or {@link #setBeamPushUrisCallback} is called with a null callback,
972     * then the Uri push will be completely disabled for the specified activity(s).
973     *
974     * <p>Code example:
975     * <pre>
976     * protected void onCreate(Bundle savedInstanceState) {
977     *     super.onCreate(savedInstanceState);
978     *     NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
979     *     if (nfcAdapter == null) return;  // NFC not available on this device
980     *     nfcAdapter.setBeamPushUrisCallback(callback, this);
981     * }</pre>
982     * And that is it. Only one call per activity is necessary. The Android
983     * OS will automatically release its references to the Uri(s) and the
984     * Activity object when it is destroyed if you follow this pattern.
985     *
986     * <p class="note">Do not pass in an Activity that has already been through
987     * {@link Activity#onDestroy}. This is guaranteed if you call this API
988     * during {@link Activity#onCreate}.
989     *
990     * <p class="note">If this device does not support alternate transports
991     * such as Bluetooth or WiFI, calling this method does nothing.
992     *
993     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
994     *
995     * @param callback callback, or null to disable
996     * @param activity activity for which the Uri(s) will be pushed
997     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
998     */
999    public void setBeamPushUrisCallback(CreateBeamUrisCallback callback, Activity activity) {
1000        synchronized (NfcAdapter.class) {
1001            if (!sHasNfcFeature) {
1002                throw new UnsupportedOperationException();
1003            }
1004        }
1005        if (activity == null) {
1006            throw new NullPointerException("activity cannot be null");
1007        }
1008        mNfcActivityManager.setNdefPushContentUriCallback(activity, callback);
1009    }
1010
1011    /**
1012     * Set a static {@link NdefMessage} to send using Android Beam (TM).
1013     *
1014     * <p>This method may be called at any time before {@link Activity#onDestroy},
1015     * but the NDEF message is only made available for NDEF push when the
1016     * specified activity(s) are in resumed (foreground) state. The recommended
1017     * approach is to call this method during your Activity's
1018     * {@link Activity#onCreate} - see sample
1019     * code below. This method does not immediately perform any I/O or blocking work,
1020     * so is safe to call on your main thread.
1021     *
1022     * <p>Only one NDEF message can be pushed by the currently resumed activity.
1023     * If both {@link #setNdefPushMessage} and
1024     * {@link #setNdefPushMessageCallback} are set, then
1025     * the callback will take priority.
1026     *
1027     * <p>If neither {@link #setNdefPushMessage} or
1028     * {@link #setNdefPushMessageCallback} have been called for your activity, then
1029     * the Android OS may choose to send a default NDEF message on your behalf,
1030     * such as a URI for your application.
1031     *
1032     * <p>If {@link #setNdefPushMessage} is called with a null NDEF message,
1033     * and/or {@link #setNdefPushMessageCallback} is called with a null callback,
1034     * then NDEF push will be completely disabled for the specified activity(s).
1035     * This also disables any default NDEF message the Android OS would have
1036     * otherwise sent on your behalf for those activity(s).
1037     *
1038     * <p>If you want to prevent the Android OS from sending default NDEF
1039     * messages completely (for all activities), you can include a
1040     * {@code <meta-data>} element inside the {@code <application>}
1041     * element of your AndroidManifest.xml file, like this:
1042     * <pre>
1043     * &lt;application ...>
1044     *     &lt;meta-data android:name="android.nfc.disable_beam_default"
1045     *         android:value="true" />
1046     * &lt;/application></pre>
1047     *
1048     * <p>The API allows for multiple activities to be specified at a time,
1049     * but it is strongly recommended to just register one at a time,
1050     * and to do so during the activity's {@link Activity#onCreate}. For example:
1051     * <pre>
1052     * protected void onCreate(Bundle savedInstanceState) {
1053     *     super.onCreate(savedInstanceState);
1054     *     NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
1055     *     if (nfcAdapter == null) return;  // NFC not available on this device
1056     *     nfcAdapter.setNdefPushMessage(ndefMessage, this);
1057     * }</pre>
1058     * And that is it. Only one call per activity is necessary. The Android
1059     * OS will automatically release its references to the NDEF message and the
1060     * Activity object when it is destroyed if you follow this pattern.
1061     *
1062     * <p>If your Activity wants to dynamically generate an NDEF message,
1063     * then set a callback using {@link #setNdefPushMessageCallback} instead
1064     * of a static message.
1065     *
1066     * <p class="note">Do not pass in an Activity that has already been through
1067     * {@link Activity#onDestroy}. This is guaranteed if you call this API
1068     * during {@link Activity#onCreate}.
1069     *
1070     * <p class="note">For sending large content such as pictures and songs,
1071     * consider using {@link #setBeamPushUris}, which switches to alternate transports
1072     * such as Bluetooth to achieve a fast transfer rate.
1073     *
1074     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1075     *
1076     * @param message NDEF message to push over NFC, or null to disable
1077     * @param activity activity for which the NDEF message will be pushed
1078     * @param activities optional additional activities, however we strongly recommend
1079     *        to only register one at a time, and to do so in that activity's
1080     *        {@link Activity#onCreate}
1081     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1082     */
1083    public void setNdefPushMessage(NdefMessage message, Activity activity,
1084            Activity ... activities) {
1085        synchronized (NfcAdapter.class) {
1086            if (!sHasNfcFeature) {
1087                throw new UnsupportedOperationException();
1088            }
1089        }
1090        int targetSdkVersion = getSdkVersion();
1091        try {
1092            if (activity == null) {
1093                throw new NullPointerException("activity cannot be null");
1094            }
1095            mNfcActivityManager.setNdefPushMessage(activity, message, 0);
1096            for (Activity a : activities) {
1097                if (a == null) {
1098                    throw new NullPointerException("activities cannot contain null");
1099                }
1100                mNfcActivityManager.setNdefPushMessage(a, message, 0);
1101            }
1102        } catch (IllegalStateException e) {
1103            if (targetSdkVersion < android.os.Build.VERSION_CODES.JELLY_BEAN) {
1104                // Less strict on old applications - just log the error
1105                Log.e(TAG, "Cannot call API with Activity that has already " +
1106                        "been destroyed", e);
1107            } else {
1108                // Prevent new applications from making this mistake, re-throw
1109                throw(e);
1110            }
1111        }
1112    }
1113
1114    /**
1115     * @hide
1116     */
1117    @SystemApi
1118    public void setNdefPushMessage(NdefMessage message, Activity activity, int flags) {
1119        synchronized (NfcAdapter.class) {
1120            if (!sHasNfcFeature) {
1121                throw new UnsupportedOperationException();
1122            }
1123        }
1124        if (activity == null) {
1125            throw new NullPointerException("activity cannot be null");
1126        }
1127        mNfcActivityManager.setNdefPushMessage(activity, message, flags);
1128    }
1129
1130    /**
1131     * Set a callback that dynamically generates NDEF messages to send using Android Beam (TM).
1132     *
1133     * <p>This method may be called at any time before {@link Activity#onDestroy},
1134     * but the NDEF message callback can only occur when the
1135     * specified activity(s) are in resumed (foreground) state. The recommended
1136     * approach is to call this method during your Activity's
1137     * {@link Activity#onCreate} - see sample
1138     * code below. This method does not immediately perform any I/O or blocking work,
1139     * so is safe to call on your main thread.
1140     *
1141     * <p>Only one NDEF message can be pushed by the currently resumed activity.
1142     * If both {@link #setNdefPushMessage} and
1143     * {@link #setNdefPushMessageCallback} are set, then
1144     * the callback will take priority.
1145     *
1146     * <p>If neither {@link #setNdefPushMessage} or
1147     * {@link #setNdefPushMessageCallback} have been called for your activity, then
1148     * the Android OS may choose to send a default NDEF message on your behalf,
1149     * such as a URI for your application.
1150     *
1151     * <p>If {@link #setNdefPushMessage} is called with a null NDEF message,
1152     * and/or {@link #setNdefPushMessageCallback} is called with a null callback,
1153     * then NDEF push will be completely disabled for the specified activity(s).
1154     * This also disables any default NDEF message the Android OS would have
1155     * otherwise sent on your behalf for those activity(s).
1156     *
1157     * <p>If you want to prevent the Android OS from sending default NDEF
1158     * messages completely (for all activities), you can include a
1159     * {@code <meta-data>} element inside the {@code <application>}
1160     * element of your AndroidManifest.xml file, like this:
1161     * <pre>
1162     * &lt;application ...>
1163     *     &lt;meta-data android:name="android.nfc.disable_beam_default"
1164     *         android:value="true" />
1165     * &lt;/application></pre>
1166     *
1167     * <p>The API allows for multiple activities to be specified at a time,
1168     * but it is strongly recommended to just register one at a time,
1169     * and to do so during the activity's {@link Activity#onCreate}. For example:
1170     * <pre>
1171     * protected void onCreate(Bundle savedInstanceState) {
1172     *     super.onCreate(savedInstanceState);
1173     *     NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
1174     *     if (nfcAdapter == null) return;  // NFC not available on this device
1175     *     nfcAdapter.setNdefPushMessageCallback(callback, this);
1176     * }</pre>
1177     * And that is it. Only one call per activity is necessary. The Android
1178     * OS will automatically release its references to the callback and the
1179     * Activity object when it is destroyed if you follow this pattern.
1180     *
1181     * <p class="note">Do not pass in an Activity that has already been through
1182     * {@link Activity#onDestroy}. This is guaranteed if you call this API
1183     * during {@link Activity#onCreate}.
1184     * <p class="note">For sending large content such as pictures and songs,
1185     * consider using {@link #setBeamPushUris}, which switches to alternate transports
1186     * such as Bluetooth to achieve a fast transfer rate.
1187     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1188     *
1189     * @param callback callback, or null to disable
1190     * @param activity activity for which the NDEF message will be pushed
1191     * @param activities optional additional activities, however we strongly recommend
1192     *        to only register one at a time, and to do so in that activity's
1193     *        {@link Activity#onCreate}
1194     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1195     */
1196    public void setNdefPushMessageCallback(CreateNdefMessageCallback callback, Activity activity,
1197            Activity ... activities) {
1198        synchronized (NfcAdapter.class) {
1199            if (!sHasNfcFeature) {
1200                throw new UnsupportedOperationException();
1201            }
1202        }
1203        int targetSdkVersion = getSdkVersion();
1204        try {
1205            if (activity == null) {
1206                throw new NullPointerException("activity cannot be null");
1207            }
1208            mNfcActivityManager.setNdefPushMessageCallback(activity, callback, 0);
1209            for (Activity a : activities) {
1210                if (a == null) {
1211                    throw new NullPointerException("activities cannot contain null");
1212                }
1213                mNfcActivityManager.setNdefPushMessageCallback(a, callback, 0);
1214            }
1215        } catch (IllegalStateException e) {
1216            if (targetSdkVersion < android.os.Build.VERSION_CODES.JELLY_BEAN) {
1217                // Less strict on old applications - just log the error
1218                Log.e(TAG, "Cannot call API with Activity that has already " +
1219                        "been destroyed", e);
1220            } else {
1221                // Prevent new applications from making this mistake, re-throw
1222                throw(e);
1223            }
1224        }
1225    }
1226
1227    /**
1228     * @hide
1229     */
1230    public void setNdefPushMessageCallback(CreateNdefMessageCallback callback, Activity activity,
1231            int flags) {
1232        if (activity == null) {
1233            throw new NullPointerException("activity cannot be null");
1234        }
1235        mNfcActivityManager.setNdefPushMessageCallback(activity, callback, flags);
1236    }
1237
1238    /**
1239     * Set a callback on successful Android Beam (TM).
1240     *
1241     * <p>This method may be called at any time before {@link Activity#onDestroy},
1242     * but the callback can only occur when the
1243     * specified activity(s) are in resumed (foreground) state. The recommended
1244     * approach is to call this method during your Activity's
1245     * {@link Activity#onCreate} - see sample
1246     * code below. This method does not immediately perform any I/O or blocking work,
1247     * so is safe to call on your main thread.
1248     *
1249     * <p>The API allows for multiple activities to be specified at a time,
1250     * but it is strongly recommended to just register one at a time,
1251     * and to do so during the activity's {@link Activity#onCreate}. For example:
1252     * <pre>
1253     * protected void onCreate(Bundle savedInstanceState) {
1254     *     super.onCreate(savedInstanceState);
1255     *     NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
1256     *     if (nfcAdapter == null) return;  // NFC not available on this device
1257     *     nfcAdapter.setOnNdefPushCompleteCallback(callback, this);
1258     * }</pre>
1259     * And that is it. Only one call per activity is necessary. The Android
1260     * OS will automatically release its references to the callback and the
1261     * Activity object when it is destroyed if you follow this pattern.
1262     *
1263     * <p class="note">Do not pass in an Activity that has already been through
1264     * {@link Activity#onDestroy}. This is guaranteed if you call this API
1265     * during {@link Activity#onCreate}.
1266     *
1267     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1268     *
1269     * @param callback callback, or null to disable
1270     * @param activity activity for which the NDEF message will be pushed
1271     * @param activities optional additional activities, however we strongly recommend
1272     *        to only register one at a time, and to do so in that activity's
1273     *        {@link Activity#onCreate}
1274     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1275     */
1276    public void setOnNdefPushCompleteCallback(OnNdefPushCompleteCallback callback,
1277            Activity activity, Activity ... activities) {
1278        synchronized (NfcAdapter.class) {
1279            if (!sHasNfcFeature) {
1280                throw new UnsupportedOperationException();
1281            }
1282        }
1283        int targetSdkVersion = getSdkVersion();
1284        try {
1285            if (activity == null) {
1286                throw new NullPointerException("activity cannot be null");
1287            }
1288            mNfcActivityManager.setOnNdefPushCompleteCallback(activity, callback);
1289            for (Activity a : activities) {
1290                if (a == null) {
1291                    throw new NullPointerException("activities cannot contain null");
1292                }
1293                mNfcActivityManager.setOnNdefPushCompleteCallback(a, callback);
1294            }
1295        } catch (IllegalStateException e) {
1296            if (targetSdkVersion < android.os.Build.VERSION_CODES.JELLY_BEAN) {
1297                // Less strict on old applications - just log the error
1298                Log.e(TAG, "Cannot call API with Activity that has already " +
1299                        "been destroyed", e);
1300            } else {
1301                // Prevent new applications from making this mistake, re-throw
1302                throw(e);
1303            }
1304        }
1305    }
1306
1307    /**
1308     * Enable foreground dispatch to the given Activity.
1309     *
1310     * <p>This will give give priority to the foreground activity when
1311     * dispatching a discovered {@link Tag} to an application.
1312     *
1313     * <p>If any IntentFilters are provided to this method they are used to match dispatch Intents
1314     * for both the {@link NfcAdapter#ACTION_NDEF_DISCOVERED} and
1315     * {@link NfcAdapter#ACTION_TAG_DISCOVERED}. Since {@link NfcAdapter#ACTION_TECH_DISCOVERED}
1316     * relies on meta data outside of the IntentFilter matching for that dispatch Intent is handled
1317     * by passing in the tech lists separately. Each first level entry in the tech list represents
1318     * an array of technologies that must all be present to match. If any of the first level sets
1319     * match then the dispatch is routed through the given PendingIntent. In other words, the second
1320     * level is ANDed together and the first level entries are ORed together.
1321     *
1322     * <p>If you pass {@code null} for both the {@code filters} and {@code techLists} parameters
1323     * that acts a wild card and will cause the foreground activity to receive all tags via the
1324     * {@link NfcAdapter#ACTION_TAG_DISCOVERED} intent.
1325     *
1326     * <p>This method must be called from the main thread, and only when the activity is in the
1327     * foreground (resumed). Also, activities must call {@link #disableForegroundDispatch} before
1328     * the completion of their {@link Activity#onPause} callback to disable foreground dispatch
1329     * after it has been enabled.
1330     *
1331     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1332     *
1333     * @param activity the Activity to dispatch to
1334     * @param intent the PendingIntent to start for the dispatch
1335     * @param filters the IntentFilters to override dispatching for, or null to always dispatch
1336     * @param techLists the tech lists used to perform matching for dispatching of the
1337     *      {@link NfcAdapter#ACTION_TECH_DISCOVERED} intent
1338     * @throws IllegalStateException if the Activity is not currently in the foreground
1339     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1340     */
1341    public void enableForegroundDispatch(Activity activity, PendingIntent intent,
1342            IntentFilter[] filters, String[][] techLists) {
1343        synchronized (NfcAdapter.class) {
1344            if (!sHasNfcFeature) {
1345                throw new UnsupportedOperationException();
1346            }
1347        }
1348        if (activity == null || intent == null) {
1349            throw new NullPointerException();
1350        }
1351        if (!activity.isResumed()) {
1352            throw new IllegalStateException("Foreground dispatch can only be enabled " +
1353                    "when your activity is resumed");
1354        }
1355        try {
1356            TechListParcel parcel = null;
1357            if (techLists != null && techLists.length > 0) {
1358                parcel = new TechListParcel(techLists);
1359            }
1360            ActivityThread.currentActivityThread().registerOnActivityPausedListener(activity,
1361                    mForegroundDispatchListener);
1362            sService.setForegroundDispatch(intent, filters, parcel);
1363        } catch (RemoteException e) {
1364            attemptDeadServiceRecovery(e);
1365        }
1366    }
1367
1368    /**
1369     * Disable foreground dispatch to the given activity.
1370     *
1371     * <p>After calling {@link #enableForegroundDispatch}, an activity
1372     * must call this method before its {@link Activity#onPause} callback
1373     * completes.
1374     *
1375     * <p>This method must be called from the main thread.
1376     *
1377     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1378     *
1379     * @param activity the Activity to disable dispatch to
1380     * @throws IllegalStateException if the Activity has already been paused
1381     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1382     */
1383    public void disableForegroundDispatch(Activity activity) {
1384        synchronized (NfcAdapter.class) {
1385            if (!sHasNfcFeature) {
1386                throw new UnsupportedOperationException();
1387            }
1388        }
1389        ActivityThread.currentActivityThread().unregisterOnActivityPausedListener(activity,
1390                mForegroundDispatchListener);
1391        disableForegroundDispatchInternal(activity, false);
1392    }
1393
1394    OnActivityPausedListener mForegroundDispatchListener = new OnActivityPausedListener() {
1395        @Override
1396        public void onPaused(Activity activity) {
1397            disableForegroundDispatchInternal(activity, true);
1398        }
1399    };
1400
1401    void disableForegroundDispatchInternal(Activity activity, boolean force) {
1402        try {
1403            sService.setForegroundDispatch(null, null, null);
1404            if (!force && !activity.isResumed()) {
1405                throw new IllegalStateException("You must disable foreground dispatching " +
1406                        "while your activity is still resumed");
1407            }
1408        } catch (RemoteException e) {
1409            attemptDeadServiceRecovery(e);
1410        }
1411    }
1412
1413    /**
1414     * Limit the NFC controller to reader mode while this Activity is in the foreground.
1415     *
1416     * <p>In this mode the NFC controller will only act as an NFC tag reader/writer,
1417     * thus disabling any peer-to-peer (Android Beam) and card-emulation modes of
1418     * the NFC adapter on this device.
1419     *
1420     * <p>Use {@link #FLAG_READER_SKIP_NDEF_CHECK} to prevent the platform from
1421     * performing any NDEF checks in reader mode. Note that this will prevent the
1422     * {@link Ndef} tag technology from being enumerated on the tag, and that
1423     * NDEF-based tag dispatch will not be functional.
1424     *
1425     * <p>For interacting with tags that are emulated on another Android device
1426     * using Android's host-based card-emulation, the recommended flags are
1427     * {@link #FLAG_READER_NFC_A} and {@link #FLAG_READER_SKIP_NDEF_CHECK}.
1428     *
1429     * @param activity the Activity that requests the adapter to be in reader mode
1430     * @param callback the callback to be called when a tag is discovered
1431     * @param flags Flags indicating poll technologies and other optional parameters
1432     * @param extras Additional extras for configuring reader mode.
1433     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1434     */
1435    public void enableReaderMode(Activity activity, ReaderCallback callback, int flags,
1436            Bundle extras) {
1437        synchronized (NfcAdapter.class) {
1438            if (!sHasNfcFeature) {
1439                throw new UnsupportedOperationException();
1440            }
1441        }
1442        mNfcActivityManager.enableReaderMode(activity, callback, flags, extras);
1443    }
1444
1445    /**
1446     * Restore the NFC adapter to normal mode of operation: supporting
1447     * peer-to-peer (Android Beam), card emulation, and polling for
1448     * all supported tag technologies.
1449     *
1450     * @param activity the Activity that currently has reader mode enabled
1451     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1452     */
1453    public void disableReaderMode(Activity activity) {
1454        synchronized (NfcAdapter.class) {
1455            if (!sHasNfcFeature) {
1456                throw new UnsupportedOperationException();
1457            }
1458        }
1459        mNfcActivityManager.disableReaderMode(activity);
1460    }
1461
1462    /**
1463     * Manually invoke Android Beam to share data.
1464     *
1465     * <p>The Android Beam animation is normally only shown when two NFC-capable
1466     * devices come into range.
1467     * By calling this method, an Activity can invoke the Beam animation directly
1468     * even if no other NFC device is in range yet. The Beam animation will then
1469     * prompt the user to tap another NFC-capable device to complete the data
1470     * transfer.
1471     *
1472     * <p>The main advantage of using this method is that it avoids the need for the
1473     * user to tap the screen to complete the transfer, as this method already
1474     * establishes the direction of the transfer and the consent of the user to
1475     * share data. Callers are responsible for making sure that the user has
1476     * consented to sharing data on NFC tap.
1477     *
1478     * <p>Note that to use this method, the passed in Activity must have already
1479     * set data to share over Beam by using method calls such as
1480     * {@link #setNdefPushMessageCallback} or
1481     * {@link #setBeamPushUrisCallback}.
1482     *
1483     * @param activity the current foreground Activity that has registered data to share
1484     * @return whether the Beam animation was successfully invoked
1485     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1486     */
1487    public boolean invokeBeam(Activity activity) {
1488        synchronized (NfcAdapter.class) {
1489            if (!sHasNfcFeature) {
1490                throw new UnsupportedOperationException();
1491            }
1492        }
1493        if (activity == null) {
1494            throw new NullPointerException("activity may not be null.");
1495        }
1496        enforceResumed(activity);
1497        try {
1498            sService.invokeBeam();
1499            return true;
1500        } catch (RemoteException e) {
1501            Log.e(TAG, "invokeBeam: NFC process has died.");
1502            attemptDeadServiceRecovery(e);
1503            return false;
1504        }
1505    }
1506
1507    /**
1508     * @hide
1509     */
1510    public boolean invokeBeam(BeamShareData shareData) {
1511        try {
1512            Log.e(TAG, "invokeBeamInternal()");
1513            sService.invokeBeamInternal(shareData);
1514            return true;
1515        } catch (RemoteException e) {
1516            Log.e(TAG, "invokeBeam: NFC process has died.");
1517            attemptDeadServiceRecovery(e);
1518            return false;
1519        }
1520    }
1521
1522    /**
1523     * Enable NDEF message push over NFC while this Activity is in the foreground.
1524     *
1525     * <p>You must explicitly call this method every time the activity is
1526     * resumed, and you must call {@link #disableForegroundNdefPush} before
1527     * your activity completes {@link Activity#onPause}.
1528     *
1529     * <p>Strongly recommend to use the new {@link #setNdefPushMessage}
1530     * instead: it automatically hooks into your activity life-cycle,
1531     * so you do not need to call enable/disable in your onResume/onPause.
1532     *
1533     * <p>For NDEF push to function properly the other NFC device must
1534     * support either NFC Forum's SNEP (Simple Ndef Exchange Protocol), or
1535     * Android's "com.android.npp" (Ndef Push Protocol). This was optional
1536     * on Gingerbread level Android NFC devices, but SNEP is mandatory on
1537     * Ice-Cream-Sandwich and beyond.
1538     *
1539     * <p>This method must be called from the main thread.
1540     *
1541     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1542     *
1543     * @param activity foreground activity
1544     * @param message a NDEF Message to push over NFC
1545     * @throws IllegalStateException if the activity is not currently in the foreground
1546     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1547     * @deprecated use {@link #setNdefPushMessage} instead
1548     */
1549    @Deprecated
1550    public void enableForegroundNdefPush(Activity activity, NdefMessage message) {
1551        synchronized (NfcAdapter.class) {
1552            if (!sHasNfcFeature) {
1553                throw new UnsupportedOperationException();
1554            }
1555        }
1556        if (activity == null || message == null) {
1557            throw new NullPointerException();
1558        }
1559        enforceResumed(activity);
1560        mNfcActivityManager.setNdefPushMessage(activity, message, 0);
1561    }
1562
1563    /**
1564     * Disable NDEF message push over P2P.
1565     *
1566     * <p>After calling {@link #enableForegroundNdefPush}, an activity
1567     * must call this method before its {@link Activity#onPause} callback
1568     * completes.
1569     *
1570     * <p>Strongly recommend to use the new {@link #setNdefPushMessage}
1571     * instead: it automatically hooks into your activity life-cycle,
1572     * so you do not need to call enable/disable in your onResume/onPause.
1573     *
1574     * <p>This method must be called from the main thread.
1575     *
1576     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
1577     *
1578     * @param activity the Foreground activity
1579     * @throws IllegalStateException if the Activity has already been paused
1580     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1581     * @deprecated use {@link #setNdefPushMessage} instead
1582     */
1583    @Deprecated
1584    public void disableForegroundNdefPush(Activity activity) {
1585        synchronized (NfcAdapter.class) {
1586            if (!sHasNfcFeature) {
1587                throw new UnsupportedOperationException();
1588            }
1589        }
1590        if (activity == null) {
1591            throw new NullPointerException();
1592        }
1593        enforceResumed(activity);
1594        mNfcActivityManager.setNdefPushMessage(activity, null, 0);
1595        mNfcActivityManager.setNdefPushMessageCallback(activity, null, 0);
1596        mNfcActivityManager.setOnNdefPushCompleteCallback(activity, null);
1597    }
1598
1599    /**
1600     * Enable NDEF Push feature.
1601     * <p>This API is for the Settings application.
1602     * @hide
1603     */
1604    @SystemApi
1605    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
1606    public boolean enableNdefPush() {
1607        if (!sHasNfcFeature) {
1608            throw new UnsupportedOperationException();
1609        }
1610        try {
1611            return sService.enableNdefPush();
1612        } catch (RemoteException e) {
1613            attemptDeadServiceRecovery(e);
1614            return false;
1615        }
1616    }
1617
1618    /**
1619     * Disable NDEF Push feature.
1620     * <p>This API is for the Settings application.
1621     * @hide
1622     */
1623    @SystemApi
1624    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
1625    public boolean disableNdefPush() {
1626        synchronized (NfcAdapter.class) {
1627            if (!sHasNfcFeature) {
1628                throw new UnsupportedOperationException();
1629            }
1630        }
1631        try {
1632            return sService.disableNdefPush();
1633        } catch (RemoteException e) {
1634            attemptDeadServiceRecovery(e);
1635            return false;
1636        }
1637    }
1638
1639    /**
1640     * Return true if the NDEF Push (Android Beam) feature is enabled.
1641     * <p>This function will return true only if both NFC is enabled, and the
1642     * NDEF Push feature is enabled.
1643     * <p>Note that if NFC is enabled but NDEF Push is disabled then this
1644     * device can still <i>receive</i> NDEF messages, it just cannot send them.
1645     * <p>Applications cannot directly toggle the NDEF Push feature, but they
1646     * can request Settings UI allowing the user to toggle NDEF Push using
1647     * <code>startActivity(new Intent(Settings.ACTION_NFCSHARING_SETTINGS))</code>
1648     * <p>Example usage in an Activity that requires NDEF Push:
1649     * <p><pre>
1650     * protected void onResume() {
1651     *     super.onResume();
1652     *     if (!nfcAdapter.isEnabled()) {
1653     *         startActivity(new Intent(Settings.ACTION_NFC_SETTINGS));
1654     *     } else if (!nfcAdapter.isNdefPushEnabled()) {
1655     *         startActivity(new Intent(Settings.ACTION_NFCSHARING_SETTINGS));
1656     *     }
1657     * }</pre>
1658     *
1659     * @see android.provider.Settings#ACTION_NFCSHARING_SETTINGS
1660     * @return true if NDEF Push feature is enabled
1661     * @throws UnsupportedOperationException if FEATURE_NFC is unavailable.
1662     */
1663    public boolean isNdefPushEnabled() {
1664        synchronized (NfcAdapter.class) {
1665            if (!sHasNfcFeature) {
1666                throw new UnsupportedOperationException();
1667            }
1668        }
1669        try {
1670            return sService.isNdefPushEnabled();
1671        } catch (RemoteException e) {
1672            attemptDeadServiceRecovery(e);
1673            return false;
1674        }
1675    }
1676
1677    /**
1678     * Signals that you are no longer interested in communicating with an NFC tag
1679     * for as long as it remains in range.
1680     *
1681     * All future attempted communication to this tag will fail with {@link IOException}.
1682     * The NFC controller will be put in a low-power polling mode, allowing the device
1683     * to save power in cases where it's "attached" to a tag all the time (e.g. a tag in
1684     * car dock).
1685     *
1686     * Additionally the debounceMs parameter allows you to specify for how long the tag needs
1687     * to have gone out of range, before it will be dispatched again.
1688     *
1689     * Note: the NFC controller typically polls at a pretty slow interval (100 - 500 ms).
1690     * This means that if the tag repeatedly goes in and out of range (for example, in
1691     * case of a flaky connection), and the controller happens to poll every time the
1692     * tag is out of range, it *will* re-dispatch the tag after debounceMs, despite the tag
1693     * having been "in range" during the interval.
1694     *
1695     * Note 2: if a tag with another UID is detected after this API is called, its effect
1696     * will be cancelled; if this tag shows up before the amount of time specified in
1697     * debounceMs, it will be dispatched again.
1698     *
1699     * Note 3: some tags have a random UID, in which case this API won't work reliably.
1700     *
1701     * @param tag        the {@link android.nfc.Tag Tag} to ignore.
1702     * @param debounceMs minimum amount of time the tag needs to be out of range before being
1703     *                   dispatched again.
1704     * @param tagRemovedListener listener to be called when the tag is removed from the field.
1705     *                           Note that this will only be called if the tag has been out of range
1706     *                           for at least debounceMs, or if another tag came into range before
1707     *                           debounceMs. May be null in case you don't want a callback.
1708     * @param handler the {@link android.os.Handler Handler} that will be used for delivering
1709     *                the callback. if the handler is null, then the thread used for delivering
1710     *                the callback is unspecified.
1711     * @return false if the tag couldn't be found (or has already gone out of range), true otherwise
1712     */
1713    public boolean ignore(final Tag tag, int debounceMs,
1714                          final OnTagRemovedListener tagRemovedListener, final Handler handler) {
1715        ITagRemovedCallback.Stub iListener = null;
1716        if (tagRemovedListener != null) {
1717            iListener = new ITagRemovedCallback.Stub() {
1718                @Override
1719                public void onTagRemoved() throws RemoteException {
1720                    if (handler != null) {
1721                        handler.post(new Runnable() {
1722                            @Override
1723                            public void run() {
1724                                tagRemovedListener.onTagRemoved();
1725                            }
1726                        });
1727                    } else {
1728                        tagRemovedListener.onTagRemoved();
1729                    }
1730                    synchronized (mLock) {
1731                        mTagRemovedListener = null;
1732                    }
1733                }
1734            };
1735        }
1736        synchronized (mLock) {
1737            mTagRemovedListener = iListener;
1738        }
1739        try {
1740            return sService.ignore(tag.getServiceHandle(), debounceMs, iListener);
1741        } catch (RemoteException e) {
1742            return false;
1743        }
1744    }
1745
1746    /**
1747     * Inject a mock NFC tag.<p>
1748     * Used for testing purposes.
1749     * <p class="note">Requires the
1750     * {@link android.Manifest.permission#WRITE_SECURE_SETTINGS} permission.
1751     * @hide
1752     */
1753    public void dispatch(Tag tag) {
1754        if (tag == null) {
1755            throw new NullPointerException("tag cannot be null");
1756        }
1757        try {
1758            sService.dispatch(tag);
1759        } catch (RemoteException e) {
1760            attemptDeadServiceRecovery(e);
1761        }
1762    }
1763
1764    /**
1765     * @hide
1766     */
1767    public void setP2pModes(int initiatorModes, int targetModes) {
1768        try {
1769            sService.setP2pModes(initiatorModes, targetModes);
1770        } catch (RemoteException e) {
1771            attemptDeadServiceRecovery(e);
1772        }
1773    }
1774
1775    /**
1776     * Registers a new NFC unlock handler with the NFC service.
1777     *
1778     * <p />NFC unlock handlers are intended to unlock the keyguard in the presence of a trusted
1779     * NFC device. The handler should return true if it successfully authenticates the user and
1780     * unlocks the keyguard.
1781     *
1782     * <p /> The parameter {@code tagTechnologies} determines which Tag technologies will be polled for
1783     * at the lockscreen. Polling for less tag technologies reduces latency, and so it is
1784     * strongly recommended to only provide the Tag technologies that the handler is expected to
1785     * receive. There must be at least one tag technology provided, otherwise the unlock handler
1786     * is ignored.
1787     *
1788     * @hide
1789     */
1790    @SystemApi
1791    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
1792    public boolean addNfcUnlockHandler(final NfcUnlockHandler unlockHandler,
1793                                       String[] tagTechnologies) {
1794        synchronized (NfcAdapter.class) {
1795            if (!sHasNfcFeature) {
1796                throw new UnsupportedOperationException();
1797            }
1798        }
1799        // If there are no tag technologies, don't bother adding unlock handler
1800        if (tagTechnologies.length == 0) {
1801            return false;
1802        }
1803
1804        try {
1805            synchronized (mLock) {
1806                if (mNfcUnlockHandlers.containsKey(unlockHandler)) {
1807                    // update the tag technologies
1808                    sService.removeNfcUnlockHandler(mNfcUnlockHandlers.get(unlockHandler));
1809                    mNfcUnlockHandlers.remove(unlockHandler);
1810                }
1811
1812                INfcUnlockHandler.Stub iHandler = new INfcUnlockHandler.Stub() {
1813                    @Override
1814                    public boolean onUnlockAttempted(Tag tag) throws RemoteException {
1815                        return unlockHandler.onUnlockAttempted(tag);
1816                    }
1817                };
1818
1819                sService.addNfcUnlockHandler(iHandler,
1820                        Tag.getTechCodesFromStrings(tagTechnologies));
1821                mNfcUnlockHandlers.put(unlockHandler, iHandler);
1822            }
1823        } catch (RemoteException e) {
1824            attemptDeadServiceRecovery(e);
1825            return false;
1826        } catch (IllegalArgumentException e) {
1827            Log.e(TAG, "Unable to register LockscreenDispatch", e);
1828            return false;
1829        }
1830
1831        return true;
1832    }
1833
1834    /**
1835     * Removes a previously registered unlock handler. Also removes the tag technologies
1836     * associated with the removed unlock handler.
1837     *
1838     * @hide
1839     */
1840    @SystemApi
1841    @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS)
1842    public boolean removeNfcUnlockHandler(NfcUnlockHandler unlockHandler) {
1843        synchronized (NfcAdapter.class) {
1844            if (!sHasNfcFeature) {
1845                throw new UnsupportedOperationException();
1846            }
1847        }
1848        try {
1849            synchronized (mLock) {
1850                if (mNfcUnlockHandlers.containsKey(unlockHandler)) {
1851                    sService.removeNfcUnlockHandler(mNfcUnlockHandlers.remove(unlockHandler));
1852                }
1853
1854                return true;
1855            }
1856        } catch (RemoteException e) {
1857            attemptDeadServiceRecovery(e);
1858            return false;
1859        }
1860    }
1861
1862    /**
1863     * @hide
1864     */
1865    public INfcAdapterExtras getNfcAdapterExtrasInterface() {
1866        if (mContext == null) {
1867            throw new UnsupportedOperationException("You need a context on NfcAdapter to use the "
1868                    + " NFC extras APIs");
1869        }
1870        try {
1871            return sService.getNfcAdapterExtrasInterface(mContext.getPackageName());
1872        } catch (RemoteException e) {
1873            attemptDeadServiceRecovery(e);
1874            return null;
1875        }
1876    }
1877
1878    void enforceResumed(Activity activity) {
1879        if (!activity.isResumed()) {
1880            throw new IllegalStateException("API cannot be called while activity is paused");
1881        }
1882    }
1883
1884    int getSdkVersion() {
1885        if (mContext == null) {
1886            return android.os.Build.VERSION_CODES.GINGERBREAD; // best guess
1887        } else {
1888            return mContext.getApplicationInfo().targetSdkVersion;
1889        }
1890    }
1891}
1892