如何在后台淡出Mediaplayer？

public class MyService extends Service {
    private MediaPlayer mediaPlayer;
    private AudioManager audioManager;
    private BroadcastReceiver audioFocusReceiver;

    @Override
    public void onCreate() {
        super.onCreate();
        mediaPlayer = new MediaPlayer();
        audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        audioFocusReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (AudioManager.ACTION_AUDIO_BECOMING_NOISY.equals(intent.getAction())) {
                    // 处理音频焦点丢失的情况
                    fadeOutMediaPlayer();
                }
            }
        };
        registerReceiver(audioFocusReceiver, new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY));
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // 在这里开始播放音乐
        mediaPlayer.start();
        return START_STICKY;
    }

    private void fadeOutMediaPlayer() {
        final int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
        int currentVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);

        // 逐渐降低音量
        while (currentVolume > 0) {
            float volume = (float) currentVolume / maxVolume;
            mediaPlayer.setVolume(volume, volume);
            currentVolume--;
            try {
                Thread.sleep(100); // 控制音量变化的速度
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        // 停止播放并释放资源
        mediaPlayer.stop();
        mediaPlayer.release();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unregisterReceiver(audioFocusReceiver);
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}