需求：手机端音乐暂停和播放状态从服务端告诉客户端、设备端实现暂停、播放、上一首、下一首等功能
代码路径：
packages/apps/Bluetooth/src/com/android/bluetooth/avrcpcontroller/AvrcpControllerService.java
packages/apps/Bluetooth/src/com/android/bluetooth/avrcpcontroller/AvrcpControllerStateMachine.java
packages/apps/Bluetooth/src/com/android/bluetooth/a2dpsink/A2dpSinkService.java
packages/apps/Bluetooth/src/com/android/bluetooth/avrcpcontroller/AvrcpControllerService.java
packages/apps/Bluetooth/jni/com_android_bluetooth_avrcp_controller.cpp
一、蓝牙音乐播放状态
1、在AvrcpControllerService.java文件中onPlayStatusChanged()方法就是音乐播放状态改变，该方法是由JNI层中com_android_bluetooth_avrcp_controller.cpp中调用java层的
private synchronized void onPlayStatusChanged(byte[] address, byte playStatus) {if (DBG) {Log.d(TAG, "onPlayStatusChanged " + playStatus);}int playbackState = PlaybackState.STATE_NONE;switch (playStatus) {case JNI_PLAY_STATUS_STOPPED:playbackState = PlaybackState.STATE_STOPPED;break;case JNI_PLAY_STATUS_PLAYING:playbackState = PlaybackState.STATE_PLAYING;break;case JNI_PLAY_STATUS_PAUSED:playbackState = PlaybackState.STATE_PAUSED;break;case JNI_PLAY_STATUS_FWD_SEEK:playbackState = PlaybackState.STATE_FAST_FORWARDING;break;case JNI_PLAY_STATUS_REV_SEEK:playbackState = PlaybackState.STATE_REWINDING;break;default:playbackState = PlaybackState.STATE_NONE;}BluetoothDevice device = BluetoothAdapter.getDefaultAdapter().getRemoteDevice(address);AvrcpControllerStateMachine stateMachine = getStateMachine(device);if (stateMachine != null) {stateMachine.sendMessage(AvrcpControllerStateMachine.MESSAGE_PROCESS_PLAY_STATUS_CHANGED, playbackState);}}
2、在AvrcpControllerStateMachine.java文件中Connected类中MESSAGE_PROCESS_PLAY_STATUS_CHANGED消息就是处理播放状态的，然后通过广播方式把该状态发送出去
case MESSAGE_PROCESS_PLAY_STATUS_CHANGED:if (SystemProperties.get("persist.ivi.feature", "0").equals("1")) {A2dpSinkService a2dpSinkService = A2dpSinkService.getA2dpSinkService();Log.d(TAG, "the state: " + msg.arg1);if (a2dpSinkService != null && msg.arg1 != preAudioStatus) {preAudioStatus = msg.arg1;Log.d(TAG, "preAudioStatus: " + msg.arg1);if (msg.arg1 == PlaybackState.STATE_PLAYING) {//播放a2dpSinkService.informPlayState(mDevice, true);} else if (msg.arg1 == PlaybackState.STATE_PAUSED) {//暂停a2dpSinkService.informPlayState(mDevice, false);}}}Intent intent = new Intent("zqc.bluetooth.PLAY_STATUS_CHANGED");intent.putExtra("zqc.bluetooth.PLAYBACK", msg.arg1);mService.sendBroadcast(intent);mAddressedPlayer.setPlayStatus(msg.arg1);BluetoothMediaBrowserService.notifyChanged(mAddressedPlayer.getPlaybackState());if (mAddressedPlayer.getPlaybackState().getState()== PlaybackState.STATE_PLAYING&& A2dpSinkService.getFocusState() == AudioManager.AUDIOFOCUS_NONE&& !shouldRequestFocus()) {sendMessage(MSG_AVRCP_PASSTHRU,AvrcpControllerService.PASS_THRU_CMD_ID_PAUSE);}return true;
二、蓝牙音乐中怎么获取音乐信息
1、在AvrcpControllerService.java文件中onTrackChanged()方法中是获取JNI层上报的音乐信息，该方法是由JNI层中com_android_bluetooth_avrcp_controller.cpp中调用java层的
private synchronized void onTrackChanged(byte[] address, byte numAttributes, int[] attributes,String[] attribVals) {if (DBG) {Log.d(TAG, "onTrackChanged");}BluetoothDevice device = BluetoothAdapter.getDefaultAdapter().getRemoteDevice(address);AvrcpControllerStateMachine stateMachine = getStateMachine(device);//该方法就是把蓝牙音乐的信息传递给java层getElementAttrRsp(attributes,attribVals,numAttributes);if (stateMachine != null) {stateMachine.sendMessage(AvrcpControllerStateMachine.MESSAGE_PROCESS_TRACK_CHANGED,TrackInfo.getMetadata(attributes, attribVals));}}
2、在AvrcpControllerService.java文件中getElementAttrRsp()中，然后通过该方法中通过广播告诉出去
private void getElementAttrRsp(int[] attr_id,String[] textArray,byte num_attr){String artist = null;String trackTitle = null;String album = null;for (int i = 0; i < num_attr; i++){switch (attr_id[i]) {case JNI_MEDIA_ATTR_ID_TITLE:trackTitle = textArray[i];if (trackTitle == null){trackTitle = "Unknown";}break;case JNI_MEDIA_ATTR_ID_ARTIST:artist = textArray[i];if (artist == null){artist = "Unknown";}break;case JNI_MEDIA_ATTR_ID_ALBUM:album = textArray[i];if (album == null){album = "Unknown";}break;}}Intent intent = new Intent("com.android.getelementattrrsp");intent.putExtra("artist", artist);intent.putExtra("trackTitle",trackTitle);intent.putExtra("album",album);Log.d(TAG,"getElementAttrRsp,artist: " + artist + ",trackTitle: " + trackTitle + ",album: " + album);intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);sendBroadcast(intent, ProfileService.BLUETOOTH_PERM);}
三、设备蓝牙音乐中上一首、下一首、暂停功能控制手机端
1、在AvrcpControllerService.java文件中sendPassThroughCmd()方法来控制暂停、播放、上一首、下一首等功能
public synchronized void sendPassThroughCmd(BluetoothDevice device, int keyCode, int keyState) {Log.v(TAG, "sendPassThroughCmd keyCode: " + keyCode + " keyState: " + keyState);if (device == null) {Log.e(TAG, "sendPassThroughCmd Device is null");return;}AvrcpControllerStateMachine stateMachine = getStateMachine(device);if (stateMachine != null) {stateMachine.sendMessage(AvrcpControllerStateMachine.MESSAGE_SEND_PASS_THROUGH_CMD,keyCode, keyState, device);}}
2、在AvrcpControllerStateMachine.java文件中MESSAGE_SEND_PASS_THROUGH_CMD变量中通过JNI层来实现功能
case MESSAGE_SEND_PASS_THROUGH_CMD:BluetoothDevice device = (BluetoothDevice) msg.obj;mService.sendPassThroughCommandNative(Utils.getByteAddress(device), msg.arg1,msg.arg2);return true;
