我正在尝试使用服务播放音乐，但它不起作用

Question

我从这里开始服务

         Intent intent=new Intent(getActivity(),MyService.class);
        s=sn;
        u=ur;
    intent.putExtra("uri",u);
            ServiceConnection serviceConnection=new ServiceConnection() {
                @Override
                public void onServiceConnected(ComponentName name, IBinder service) {
    MyService.LocalBinder binder = (MyService.LocalBinder) service;
    myService=binder.getService();

            }

            @Override
            public void onServiceDisconnected(ComponentName name) {
                myService=null;
            }
        };
        getActivity().startService(intent);

这是我的服务等级

    public class MyService extends android.app.Service {
    MediaPlayer mediaPlayer=new MediaPlayer();

    String str;
    private final IBinder binder = new LocalBinder();
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        // str=intent.getStringExtra("uri");
        Toast.makeText(this, str, Toast.LENGTH_SHORT).show();
        this.str=intent.getStringExtra("uri");
        try {
            mediaPlayer.setDataSource(str);
        } catch (IOException e) {
            e.printStackTrace();
        }

        if(!isplaying()){
            mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                @Override
                public void onPrepared(MediaPlayer mp) {
                    startmusic();
                }
            });

        }
         return START_STICKY;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }
    public class LocalBinder extends Binder {
        MyService getService() {
            // Return this instance of LocalService so clients can call public methods.
            return MyService.this;
        }
    }
    @Override
    public IBinder onBind(Intent intent) {

        return binder;
    }
    public void startmusic(){
   mediaPlayer.start();

    }
    public void stopmusic(){
        mediaPlayer.stop();
    }
    public boolean isplaying(){
        return  mediaPlayer.isPlaying();

    }
}

我收到这个错误

java.lang.RuntimeException：无法使用 Intent { cmp=com.example.firebasemp/.MyService（有额外的）} 启动服务 com.example.firebasemp.MyService@da4ba03：java.lang.IllegalStateException"

在这条线上 “mediaPlayer.setDataSource(str);”