實時監聽耳機拔除

當用戶正在使用咱們產品裏提供的音樂播放器播放音樂時，用戶把耳機或者藍牙耳機接入後，過一下子，用戶又把耳機給拔除，或者斷開藍牙耳機的鏈接，咱們須要暫停播放音樂，定義一個BroadcastReceiver對象，  對於有線耳機，監聽Intent.ACTION_HEADSET_PLUG系統廣播，對於藍牙耳機，監聽BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED系統廣播

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private void registerHeadsetPlugReceiver() {            IntentFilter intentFilter = new IntentFilter();            intentFilter.addAction("android.intent.action.HEADSET_PLUG");            registerReceiver(headsetPlugReceiver, intentFilter);                       // for bluetooth headset connection receiver          IntentFilter bluetoothFilter = new IntentFilter(BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED);          registerReceiver(headsetPlugReceiver, bluetoothFilter);      }              private BroadcastReceiver headsetPlugReceiver = new BroadcastReceiver() {              @Override          public void onReceive(Context context, Intent intent) {                              String action = intent.getAction();              if (BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED.equals(action)) {                  BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();                  if(BluetoothProfile.STATE_DISCONNECTED == adapter.getProfileConnectionState(BluetoothProfile.HEADSET)) {                      //Bluetooth headset is now disconnected                      handleHeadsetDisconnected();                  }              } else if ("android.intent.action.HEADSET_PLUG".equals(action)) {                  if (intent.hasExtra("state")) {                      if (intent.getIntExtra("state", 0) == 0) {                          handleHeadsetDisconnected();                      }                  }              }          }                  };

 這樣作能夠基本知足需求，但不完美，由於當拔出有線耳機時，播放器不會立刻暫停，要等上一秒鐘，纔會收到Android的系統廣播，

1	android.intent.action.HEADSET_PLUG，他說其餘音樂播放器沒有這個延遲，通過調查發現，QQ音樂確實沒有這個延遲，耳機一拔，播放器馬上暫停，

 

相關資料：從硬件層面來看，直接監聽耳機拔出事件不難，耳機的拔出和插入，會引發手機電平的變化，而後觸發什麼什麼中斷，

最終在stack overflow找到答案，監聽Android的系統廣播AudioManager.ACTION_AUDIO_BECOMING_NOISY， 可是這個廣播只是針對有線耳機，或者無線耳機的手機斷開鏈接的事件，監聽不到有線耳機和藍牙耳機的接入，但對於個人需求來講足夠了，監聽這個廣播就沒有延遲了，UI能夠當即響應

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private void registerHeadsetPlugReceiver() {            IntentFilter intentFilter = new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY);            registerReceiver(headsetPlugReceiver, intentFilter);       }              private BroadcastReceiver headsetPlugReceiver = new BroadcastReceiver() {              @Override          public void onReceive(Context context, Intent intent) {              String action = intent.getAction();              if (AudioManager.ACTION_AUDIO_BECOMING_NOISY.equals(action)) {                  handleHeadsetDisconnected();              }          }                  };