Android 蓝牙基础篇之 —— A2DP
本篇文章主要介绍 A2DP 基础操作。
- 介绍
A2DP ：Advanced Audio Distribution Profile。高质量音频数据传输的协议，其定义里了传送单声道或立体声等高质量音频（区别于蓝牙SCO链路上传输的普通语音）信息的协议和过程。A2DP的典型应用是将音乐播放器的音频数据发送到耳机或音箱。
A2DP 定义了两种角色：
Audio Source ：（音频源） 音频的输入端对音频数据进行编码，发送到Sink端。
Audio Sink ： （音频接收器） 接收到音频数据后，进行解码操作还原出音频。
- 初始化 A2DP 代理对象
private void initBluetooth() {
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
if (!mBtAdapter.isEnabled()) {
return;
}
//获取A2DP代理对象
mBtAdapter.getProfileProxy(mContext, mListener, BluetoothProfile.A2DP);
}
private void initReceiver() {
//广播接收者监听状态
IntentFilter filter = new IntentFilter(BluetoothA2dp.
ACTION_CONNECTION_STATE_CHANGED);
filter.addAction(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED);
mContext.registerReceiver(mReceiver, filter);
}- 初始化 A2DP 代理对象
private void initBluetooth() {
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
if (!mBtAdapter.isEnabled()) {
return;
}
//获取A2DP代理对象
mBtAdapter.getProfileProxy(mContext, mListener, BluetoothProfile.A2DP);
}
private void initReceiver() {
//广播接收者监听状态
IntentFilter filter = new IntentFilter(BluetoothA2dp.
ACTION_CONNECTION_STATE_CHANGED);
filter.addAction(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED);
mContext.registerReceiver(mReceiver, filter);
}- 广播接收者，获取连接状态
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
//A2DP连接状态改变
if (action != null) {
if (action.equals(BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED)) {
int state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, BluetoothA2dp.STATE_DISCONNECTED);
callBackA2dpConnectState(state);
} else if (action.equals(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED)) {
//A2DP播放状态改变
int state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, BluetoothA2dp.STATE_NOT_PLAYING);
Log.i(TAG, "play state=" + state);
}
}
}
};- 获取 A2DP 代理对象 proxy
private BluetoothProfile.ServiceListener mListener = new BluetoothProfile.ServiceListener() {
@Override
public void onServiceDisconnected(int profile) {
Log.i(TAG, "onServiceDisconnected profile=" + profile);
if (profile == BluetoothProfile.A2DP) {
mA2dp = null;
}
}
@Override
public void onServiceConnected(int profile, BluetoothProfile proxy) {
Log.i(TAG, "onServiceConnected profile=" + profile);
if (profile == BluetoothProfile.A2DP) {
mA2dp = (BluetoothA2dp) proxy; //转换
if (onBluetoothA2dpReadyListener != null) {
onBluetoothA2dpReadyListener.onBluetoothA2dpReady();
}
}
}
};- 连接
a2dp connect is hide 需要通过反射获取，连接成功之后，可以在蓝牙设备中播放音乐等音频
public void connectA2dp(BluetoothDevice device) {
Log.i(TAG, "connect to device :" + device);
mConnectDevice = device;
setPriority(device, 100); //设置priority
try {
//通过反射获取BluetoothA2dp中connect方法（hide的），进行连接。
Method connectMethod = BluetoothA2dp.class.getMethod("connect",
BluetoothDevice.class);
connectMethod.invoke(mA2dp, device);
} catch (Exception e) {
e.printStackTrace();
}
}- 断开连接
public void disConnectA2dp(BluetoothDevice device) {
mConnectDevice = null;
setPriority(device, 0);
try {
//通过反射获取BluetoothA2dp中connect方法（hide的），断开连接。
Method connectMethod = BluetoothA2dp.class.getMethod("disconnect",
BluetoothDevice.class);
connectMethod.invoke(mA2dp, device);
} catch (Exception e) {
e.printStackTrace();
}
}
- 设置优先级，一般 priority = 100
public void setPriority(BluetoothDevice device, int priority) {
if (mA2dp == null) return;
try {//通过反射获取BluetoothA2dp中setPriority方法（hide的），设置优先级
Method connectMethod = BluetoothA2dp.class.getMethod("setPriority",
BluetoothDevice.class, int.class);
connectMethod.invoke(mA2dp, device, priority);
} catch (Exception e) {
e.printStackTrace();
}
}好了，到这里相信大家都明白了，HFP 和 A2DP 的操作流程基本一样。