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