java - 以编程方式连接到配对的蓝牙扬声器并播放音频

Question

在我们的应用中，我想使用 Android v4.2 或更高版本连接到之前配对的 A2DP 蓝牙扬声器并直接向其播放音频。

我可以使用此代码成功创建 A2DP 配置文件对象以启动该过程:

---

/* Manifest permissions */
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

---

// Get the default adapter
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

// Establish connection to the proxy.
mBluetoothAdapter.getProfileProxy(this, mProfileListener, BluetoothProfile.A2DP)

和以下监听器响应连接:

private BluetoothProfile.ServiceListener mProfileListener = new BluetoothProfile.ServiceListener() {
public void onServiceConnected(int profile, BluetoothProfile proxy) {

    if (profile == BluetoothProfile.A2DP) {

        mBluetoothSpeaker = (BluetoothA2dp) proxy;

        // no devices are connected         
        List<BluetoothDevice> connectedDevices = mBluetoothSpeaker.getConnectedDevices();

        //the one paired (and disconnected) speaker is returned here
        int[] statesToCheck = {BluetoothA2dp.STATE_DISCONNECTED};           
        List<BluetoothDevice> disconnectedDevices = mBluetoothSpeaker.getDevicesMatchingConnectionStates(statesToCheck);



        BluetoothDevice btSpeaker = disconnectedDevices.get(0); 

        //WHAT NOW?

    }
}
public void onServiceDisconnected(int profile) {
    if (profile == BluetoothProfile.A2DP) {
        mBluetoothSpeaker = null;
    }
}
};

我只是有点不知道现在该做什么，连接设备，并将音频输出定向到它。我试过连接到设备，as detailed in the Android docs , 使用以下代码，但最后的 BluetoothSpeaker.getConnectedDevices()调用未返回连接的设备。

    BluetoothSocket tmp = null;
    UUID MY_UUID = UUID.fromString("00001108-0000-1000-8000-00805f9b34fb");
    try {           
        tmp = btSpeaker.createInsecureRfcommSocketToServiceRecord(MY_UUID);

    } catch (IOException e1) {
        // TODO Auto-generated catch block
        Log.d("createRfcommSocketToServiceRecord ERROR", e1.getMessage());
    }
    mmSocket = tmp;

    try {
        // Connect the device through the socket. This will block
        // until it succeeds or throws an exception
        mmSocket.connect();
    } catch (IOException connectException) {
        // Unable to connect; close the socket and get out
        try {
            Log.d("connectException", connectException.getMessage());
            mmSocket.close();
        } catch (IOException closeException) { }
        return;
    }

    connectedDevices = mBluetoothSpeaker.getConnectedDevices();

不过，代码似乎确实以某种方式连接到设备，因为当我停止执行时，蓝牙扬声器会通知它已准备好配对(当它与音频源断开连接时总是如此)。

旧版本的 BluetoothA2dp似乎有一个 connect(BluetoothDevice device)方法，但现在已被删除(从 4.2 开始)，我正在努力寻找任何清晰的示例，说明如何以编程方式连接到 A2DP 设备，并将音频输出定向到它。我们将不胜感激地收到有关如何处理其中任何一个的任何帮助。

任何有关如何处理此问题的建议都将不胜感激。

Answer 1

这个对我有用。接收到BluetoothA2dp.STATE_CONNECTED后，即可正常播放音乐。

public class A2DPActivity extends Activity {

protected static final String TAG = "ZS-A2dp";

Button mBtPlay;

BluetoothAdapter mBtAdapter;
BluetoothA2dp mA2dpService;

AudioManager mAudioManager;
MediaPlayer mPlayer;

BroadcastReceiver mReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context ctx, Intent intent) {
        String action = intent.getAction();
        Log.d(TAG, "receive intent for action : " + action);
        if (action.equals(BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED)) {
            int state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, BluetoothA2dp.STATE_DISCONNECTED);
            if (state == BluetoothA2dp.STATE_CONNECTED) {
                setIsA2dpReady(true);
                playMusic();
            } else if (state == BluetoothA2dp.STATE_DISCONNECTED) {
                setIsA2dpReady(false);
            }
        } else if (action.equals(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED)) {
            int state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, BluetoothA2dp.STATE_NOT_PLAYING);
            if (state == BluetoothA2dp.STATE_PLAYING) {
                Log.d(TAG, "A2DP start playing");
                Toast.makeText(A2DPActivity.this, "A2dp is playing", Toast.LENGTH_SHORT).show();
            } else {
                Log.d(TAG, "A2DP stop playing");
                Toast.makeText(A2DPActivity.this, "A2dp is stopped", Toast.LENGTH_SHORT).show();
            }
        }
    }

};

boolean mIsA2dpReady = false;
void setIsA2dpReady(boolean ready) {
    mIsA2dpReady = ready;
    Toast.makeText(this, "A2DP ready ? " + (ready ? "true" : "false"), Toast.LENGTH_SHORT).show();
}

private ServiceListener mA2dpListener = new ServiceListener() {

    @Override
    public void onServiceConnected(int profile, BluetoothProfile a2dp) {
        Log.d(TAG, "a2dp service connected. profile = " + profile);
        if (profile == BluetoothProfile.A2DP) {
            mA2dpService = (BluetoothA2dp) a2dp;
            if (mAudioManager.isBluetoothA2dpOn()) {
                setIsA2dpReady(true);
                playMusic();
            } else {
                Log.d(TAG, "bluetooth a2dp is not on while service connected");
            }
        }
    }

    @Override
    public void onServiceDisconnected(int profile) {
        setIsA2dpReady(false);
    }

};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    LinearLayout ll = new LinearLayout(this);
    setContentView(ll);

    mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    registerReceiver(mReceiver, new IntentFilter(BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED));
    registerReceiver(mReceiver, new IntentFilter(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED));

    mBtAdapter = BluetoothAdapter.getDefaultAdapter();
    mBtAdapter.getProfileProxy(this, mA2dpListener , BluetoothProfile.A2DP);

}

@Override
protected void onDestroy() {
    mBtAdapter.closeProfileProxy(BluetoothProfile.A2DP, mA2dpService);
    releaseMediaPlayer();
    unregisterReceiver(mReceiver);
    super.onDestroy();
}

@Override
protected void onPause() {
    releaseMediaPlayer();
    super.onPause();
}

private void releaseMediaPlayer() {
    if (mPlayer != null) {
        mPlayer.release();
        mPlayer = null;
    }
}

private void playMusic() {
    mPlayer = new MediaPlayer();
    AssetManager assetManager = this.getAssets();
    AssetFileDescriptor fd;
    try {
        fd = assetManager.openFd("Radioactive.mp3");
        Log.d(TAG, "fd = " + fd);
        mPlayer.setDataSource(fd.getFileDescriptor());
        mPlayer.prepare();
        Log.d(TAG, "start play music");
        mPlayer.start();
    } catch (IOException e) {
        e.printStackTrace();
    }
}