Android NFC 文件传输

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mUris = new ArrayList<Uri>();
        mNdefMessage = null;
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        mLaunchIntent = getIntent();
        if (mNfcAdapter == null) {
            ......
        } else {
            // NFC 没打开则先弹出请求打开 NFC 的请求框 
            if (!mNfcAdapter.isEnabled()) {
                showNfcDialogAndExit(com.android.nfc.R.string.beam_requires_nfc_enabled);
            } else {
                parseShareIntentAndFinish(mLaunchIntent);
            }
        }
    }

    public void parseShareIntentAndFinish(Intent intent) {
 	......  //从intent 中获取 uri 

	//创建并填充 BeamShareData 变量
        BeamShareData shareData = null;
        UserHandle myUserHandle = new UserHandle(UserHandle.myUserId());
        if (mUris.size() > 0) {
            // Uris have our first preference for sharing
            Uri[] uriArray = new Uri[mUris.size()];
            int numValidUris = 0;
            for (Uri uri : mUris) {
                try {
                    int uid = ActivityManagerNative.getDefault().getLaunchedFromUid(getActivityToken());
                    grantUriPermission("com.android.nfc", uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);
                    uriArray[numValidUris++] = uri;
                    if (DBG) Log.d(TAG, "Found uri: " + uri);
                } 
            }
            if (numValidUris != 0 && numValidUris == mUris.size()) {
                shareData = new BeamShareData(null, uriArray, myUserHandle, 0);
            } else {
                // No uris left
                shareData = new BeamShareData(null, null, myUserHandle, 0);
            }
        } ......
        mNfcAdapter.invokeBeam(shareData);
        finish();
    }

        public void invokeBeamInternal(BeamShareData shareData) {
            NfcPermissions.enforceAdminPermissions(mContext);
            Message msg = Message.obtain();
            msg.what = MSG_INVOKE_BEAM;
            msg.obj = shareData;
            mHandler.sendMessageDelayed(msg, INVOKE_BEAM_DELAY_MS);
        }
        
=>           case MSG_INVOKE_BEAM: {
                    mP2pLinkManager.onManualBeamInvoke((BeamShareData)msg.obj);
                    break;
                }        

    public void onManualBeamInvoke(BeamShareData shareData) {
        synchronized (P2pLinkManager.this)    {
            ......
            if (mMessageToSend != null ||
                    (mUrisToSend != null && mHandoverDataParser.isHandoverSupported())) {
                mSendState = SEND_STATE_PENDING;
                mEventListener.onP2pNfcTapRequested();
                scheduleTimeoutLocked(MSG_WAIT_FOR_LINK_TIMEOUT, WAIT_FOR_LINK_TIMEOUT_MS);
            }
        }
    }
    
    // 播放start 的声音， 此外截图并显出出 Android Beam 界面
     public void onP2pNfcTapRequested() {
        mNfcService.playSound(NfcService.SOUND_START);
        mNdefSent = false;
        mNdefReceived = false;
        mInDebounce = false;

        mVibrator.vibrate(VIBRATION_PATTERN, -1);
        if (mSendUi != null) {
            mSendUi.takeScreenshot();
            mSendUi.showPreSend(true);     

    final class ConnectTask extends AsyncTask<Void, Void, Boolean> {
        @Override
        protected void onPostExecute(Boolean result)  {
                onLlcpServicesConnected();
        }
    }        
            
    void onLlcpServicesConnected() {
            mLlcpServicesConnected = true;
            if (mSendState == SEND_STATE_NEED_CONFIRMATION) {
		.......
            } else if (mSendState == SEND_STATE_SENDING) {
                mEventListener.onP2pResumeSend();
                sendNdefMessage();
            } 
        }
    void sendNdefMessage() {
        synchronized (this) {
            cancelSendNdefMessage();
            mSendTask = new SendTask();
            mSendTask.execute();
        }
    }        

    public boolean startBeamSend(Context context,
                               HandoverDataParser.BluetoothHandoverData outgoingHandoverData,
                               Uri[] uris, UserHandle userHandle) {
                mBeamInProgress = true;

        BeamTransferRecord transferRecord = BeamTransferRecord.forBluetoothDevice(
                outgoingHandoverData.device, outgoingHandoverData.carrierActivating,
                uris);
        Intent sendIntent = new Intent(context.getApplicationContext(),
                BeamSendService.class);
        sendIntent.putExtra(BeamSendService.EXTRA_BEAM_TRANSFER_RECORD, transferRecord);
        sendIntent.putExtra(BeamSendService.EXTRA_BEAM_COMPLETE_CALLBACK,
                new Messenger(mCallback));
        context.startServiceAsUser(sendIntent, userHandle);
        return true;
    }

public class BeamSendService extends Service implements BeamTransferManager.Callback {
    public int onStartCommand(Intent intent, int flags, int startId) {
        BeamTransferRecord transferRecord;    
        transferRecord = intent.getParcelableExtra(EXTRA_BEAM_TRANSFER_RECORD)   
        mCompleteCallback = intent.getParcelableExtra(EXTRA_BEAM_COMPLETE_CALLBACK);
        if (doTransfer(transferRecord)) {
            return START_STICKY;
        } 
    }
    
    boolean doTransfer(BeamTransferRecord transferRecord) {
        if (createBeamTransferManager(transferRecord)) {
            // register Beam status receiver
            mBeamStatusReceiver = new BeamStatusReceiver(this, mTransferManager);
            registerReceiver(mBeamStatusReceiver, mBeamStatusReceiver.getIntentFilter(),
                    BeamStatusReceiver.BEAM_STATUS_PERMISSION, new Handler());

            if (transferRecord.dataLinkType == BeamTransferRecord.DATA_LINK_TYPE_BLUETOOTH) {
                if (mBluetoothAdapter.isEnabled()) {
                    // Start the transfer
                    mTransferManager.start();
                } else {
                     //如果蓝牙当前没有开启则开启蓝牙， 等待收到开启的广播时会在调用 mTransferManager.start
                    if (!mBluetoothAdapter.enableNoAutoConnect()) {
                        Log.e(TAG, "Error enabling Bluetooth.");
                        mTransferManager = null;
                        return false;
                    }
                    mBluetoothEnabledByNfc = true;
                    if (DBG) Log.d(TAG, "Queueing out transfer "
                            + Integer.toString(transferRecord.id));
                }
            }
            return true;
        }
        return false;
    }    

public class BeamTransferManager implements Handler.Callback,
        MediaScannerConnection.OnScanCompletedListener {
    public void start() {
        mStartTime = System.currentTimeMillis();

        if (!mIncoming) {
            if (mDataLinkType == BeamTransferRecord.DATA_LINK_TYPE_BLUETOOTH) {
                new BluetoothOppHandover(mContext, mRemoteDevice, mUris, mRemoteActivating).start();
            }
        }
    }     

public class BluetoothOppHandover implements Handler.Callback {
    public void start() {
    	//如果 remote 蓝牙未开启则等待一小段时间
        if (mRemoteActivating) {
            Long timeElapsed = SystemClock.elapsedRealtime() - mCreateTime;
            if (timeElapsed < REMOTE_BT_ENABLE_DELAY_MS) {
                mHandler.sendEmptyMessageDelayed(MSG_START_SEND,
                        REMOTE_BT_ENABLE_DELAY_MS - timeElapsed);
            } else {
                // Already waited long enough for BT to come up
                // - start send.
                sendIntent();
            }
        } else {
            // Remote BT enabled already, start send immediately
            sendIntent();
        }
    }

   //发送 broadcast 交给 BT 来传输
    void sendIntent() {
        Intent intent = new Intent();
        intent.setPackage("com.android.bluetooth");
        String mimeType = MimeTypeUtil.getMimeTypeForUri(mContext, mUris.get(0));
        intent.setType(mimeType);
        intent.putExtra(BluetoothDevice.EXTRA_DEVICE, mDevice);
        if (mUris.size() == 1) {
            intent.setAction(ACTION_HANDOVER_SEND);
            intent.putExtra(Intent.EXTRA_STREAM, mUris.get(0));
        } else {
            intent.setAction(ACTION_HANDOVER_SEND_MULTIPLE);
            intent.putParcelableArrayListExtra(Intent.EXTRA_STREAM, mUris);
        }
        intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
        mContext.sendBroadcast(intent);
        complete();
    }    

public class BeamStatusReceiver extends BroadcastReceiver {

    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        int dataLinkType = intent.getIntExtra(EXTRA_HANDOVER_DATA_LINK_TYPE,
                BeamTransferManager.DATA_LINK_TYPE_BLUETOOTH);

        if (ACTION_CANCEL_HANDOVER_TRANSFER.equals(action)) {
            if (mTransferManager != null) {
                mTransferManager.cancel();
            }
        } else if (ACTION_TRANSFER_PROGRESS.equals(action) ||
                ACTION_TRANSFER_DONE.equals(action) ||
                ACTION_HANDOVER_STARTED.equals(action)) {
            handleTransferEvent(intent, dataLinkType);
        }
    }