Android实现音乐播放进度条传递信息的两种方式(在service和activity中)

//当前音乐播放进度
  private static TextView nowTime;
	//音乐进度条
  static SeekBar songseek;
  
  //运用Handler中的handleMessage方法接收service传递的音乐播放进度信息
  public static Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
      // super.handleMessage(msg);
      // 将SeekBar位置设置到当前播放位置，
      // msg.arg1是service传过来的音乐播放进度信息,将其设置为进度条进度
      songseek.setProgress(msg.arg1);
      //将进度时间其转为mm:ss时间格式
      nowTime.setText(new SimpleDateFormat("mm:ss",Locale.getDefault()).format(new Date(msg.arg1)));
      return false;
    }
  });

	//下面才是android的onCreate方法
	protected void onCreate(Bundle savedInstanceState) {
		......
	}

//开始播放音乐
    	mediaPlayer.start();
   	//每隔50毫秒发送音乐进度
   	Timer timer = new Timer();
    	timer.schedule(new TimerTask() {
    	@Override
    		public void run() {
    			//实例化一个Message对象
				Message msg = Message.obtain();
				//Message对象的arg1参数携带音乐当前播放进度信息，类型是int
      	msg.arg1 = mediaPlayer.getCurrentPosition();
      	//使用MainActivity中的handler发送信息
      	MainActivity.handler.sendMessage(msg);
    		}
    }, 0, 50);

//创建一个线程每隔100毫秒发送一次信息
    Runnable runnable = new Runnable() {
		@Override
			public void run() {
				while (true) {
					try {
						Thread.sleep(100);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
          Message msg = Message.obtain();
          msg.arg1 = mediaPlayer.getCurrentPosition();
          MainActivity.handler.sendMessage(msg);
          }
         }
      };
    Thread musicThread = new Thread(runnable);
    musicThread.start();

java.lang.IllegalStateException android.media.MediaPlayer._prepare(Native Method)

mediaPlayer.prepare();
	mediaPlayer.start();

mediaPlayer.prepareAsync();
	//需要设置一个监听器
	mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
		@Override
		public void onPrepared(MediaPlayer mp) {
			mediaPlayer.start();
		}
	});