啟用背景音訊

若要在應用程式於背景時啟用音訊播放，應用程式應呼叫 enableAudioPlaybackInBackground 當播放器處於「已準備」狀態時，具有true作為引數的MediaPlayer的API。

_mediaPlayer.enableAudioPlaybackInBackground(true);

應用程式在回應電話等事件期間失去音訊焦點保留時，應暫停播放。 下列程式碼片段示範如何實作 OnAudioFocusChangeListener：

/**
 * Register the AudioFocus Change listener to track Audio focus from device.
 */
 AudioManager.OnAudioFocusChangeListener onAudioFocusChangeListener = new AudioManager.OnAudioFocusChangeListener(){
     @Override
     public void onAudioFocusChange(int focusChange){
          switch(focusChange){
               case AudioManager.AUDIOFOCUS_GAIN:
                    break;
               case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
                    /* lower output volume*/
                    break;
               case AudioManager.AUDIOFOCUS_LOSS:
               case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
                    if(_lastKnownStatus ==MediaPlayerStatus.PLAYING)
                         _mediaPlayer.pause();
                    break;
          }
     }
};

AudioManager audioManager = (AudioManager) getActivity().getApplicationContext().getSystemService(Context.AUDIO_SERVICE);
audioManager.requestAudioFocus(onAudioFocusChangeListener, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);