应用关闭后，让应用在后台运行

Question

我正在构建一个可在手机屏幕开启或关闭时播放音频的应用。

以下是我播放音频的方式

public class LockScreenReceiver extends BroadcastReceiver {

MediaPlayer mp;
ArrayList<File> mySongs;
ArrayList<File> mySongs2;
Uri u;
Uri u2;
AudioManager am;
private static final String TAG = SecondScreen.class.getSimpleName();

@Override
public void onReceive(Context context, Intent intent) {

    String action = intent.getAction();
    am = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);

    if(action.equals("my.action")) {
            Bundle b = intent.getExtras();
            mySongs = (ArrayList) b.getParcelableArrayList("songlistLock");
            int position = b.getInt("posLock", 0);

            u = Uri.parse(mySongs.get(position).toString());
        }

        if(action.equals("my.action.unlock")) {
            Bundle b = intent.getExtras();
            mySongs2 = (ArrayList) b.getParcelableArrayList("songlistUnlock");
            int position = b.getInt("posUnlock", 0);

            u2 = Uri.parse(mySongs2.get(position).toString());
        }


    if (action.equals(Intent.ACTION_SCREEN_ON) && am.getRingerMode() == AudioManager.RINGER_MODE_NORMAL)
    {
        if(u2!=null) {
            stopPlaying();
            mp = MediaPlayer.create(context, u2);
            mp.start();
            Toast.makeText(context, "Audio on playing", Toast.LENGTH_SHORT).show();
        }
    }
    else if (action.equals(Intent.ACTION_SCREEN_OFF) && am.getRingerMode() == AudioManager.RINGER_MODE_NORMAL)
    {
        if(u!=null) {
            stopPlaying();
            mp = MediaPlayer.create(context, u);
            mp.start();
            Toast.makeText(context, "Audio off playing", Toast.LENGTH_SHORT).show();

        }
    }


}

这是我的服务类

public class LockScreenService extends Service {

BroadcastReceiver receiver;

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

@Override
@SuppressWarnings("deprecation")
public void onCreate() {

    //Start listening for the Screen On, Screen Off, and Boot completed actions
    IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
    filter.addAction(Intent.ACTION_SCREEN_OFF);
    filter.addAction(Intent.ACTION_BOOT_COMPLETED);

    //Set up a receiver to listen for the Intents in this Service
    receiver = new LockScreenReceiver();
    registerReceiver(receiver, filter);
    registerReceiver( receiver, new IntentFilter( "my.action" ) );
    registerReceiver( receiver, new IntentFilter( "my.action.unlock" ) );

   // Toast.makeText(getApplicationContext(), "Starting service now", Toast.LENGTH_SHORT).show();

    super.onCreate();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    return START_STICKY;
}

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

即使应用程序从任务管理器关闭后我想让我的应用程序能够播放音频。但START_STICKY似乎不起作用。

我错过了什么吗？我真的需要使用共享偏好吗？由于音乐文件是从用户的设备存储中提取的。