Android uses AudioManager to control the pause and play of the background music player

1.

Operate the player state by triggering the media button: KeyEvent.KEYCODE_MEDIA_PAUSE 

public static void sendMediaButton(Context context, int keyCode) {
    AudioManager audioManager= (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    //先判断后台是否再播放音乐
    if (audioManager.isMusicActive()){
        KeyEvent keyEvent = new KeyEvent(KeyEvent.ACTION_DOWN, keyCode);
        Intent intent = new Intent(Intent.ACTION_MEDIA_BUTTON);
        intent.putExtra(Intent.EXTRA_KEY_EVENT, keyEvent);
        context.sendOrderedBroadcast(intent,null);

        keyEvent = new KeyEvent(KeyEvent.ACTION_UP, keyCode);
        intent = new Intent(Intent.ACTION_MEDIA_BUTTON);
        intent.putExtra(Intent.EXTRA_KEY_EVENT, keyEvent);
        context.sendOrderedBroadcast(intent,null);
    }
}

 2. Obtain the audio focus AudioFocus through AudioManager to compete to use audio to stop playing or lower the sound.  
AudioManager am = (AudioManager) mAppContext.getSystemService(Context.AUDIO_SERVICE);  
am.requestAudioFocus(null, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN_TRANSIENT) ;  
AudioManager.AUDIOFOCUS_GAIN: Acquire media focus permanently (play music). It is estimated that the music player uses this method. It is called during video playback and does not work.  
AudioManager.AUDIOFOCUS_GAIN_TRANSIENT Temporarily obtains focus is suitable for short-lived audio  
AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK Duck our application and others When the application shares the focus, other audio will lower the volume when we play