Question

我有一个使用Android媒体播放器播放MIDI文件的应用程序。我将textview作为一个计时器，它将根据播放进度动态改变。然而，由于它陷入了2s标记，这是非常错误的

class progressTrack extends AsyncTask<String,Void,String>{

            @Override
            protected String doInBackground(String... arg0) {
                ToggleButton mStartStop;
                int currentPosition=0;
                int total=mediaPlayer.getDuration();
                TextView timer=(TextView) findViewById(R.id.timer);
                while (mediaPlayer != null && currentPosition < total) {
                    try {
                        Thread.sleep(1000);
                        currentPosition = mediaPlayer
                                .getCurrentPosition();
                        double seconds=currentPosition/1000;
                        int time= (int) Math.round(seconds);
                        String timeS=Integer.toString(time);
                        Log.d("Time",timeS);
                        timer.setText(timeS+"s");
                        fSlider.setProgress(currentPosition);
                    } catch (InterruptedException e) {

                    } catch (Exception e) {

                    }
                    OnSeekBarChangeListener listener = new OnSeekBarChangeListener() {
                        public void onStopTrackingTouch(SeekBar seekBar) { }
                        public void onStartTrackingTouch(SeekBar seekBar) { }
                        public void onProgressChanged(SeekBar seekBar, 
                                int progress,
                                boolean fromUser) {
                            if(fromUser) 
                                mediaPlayer.seekTo(progress);
                        }
                    };
                    fSlider.setOnSeekBarChangeListener(listener);
                }

时间确实在Logcat上正确显示，但为什么它不会在textview上改变？

解决：

protected void onPostExecute(String result) {

                ScheduledExecutorService myScheduledExecutorService = Executors.newScheduledThreadPool(1);
                myScheduledExecutorService.scheduleWithFixedDelay(
                         new Runnable(){
                             @Override
                             public void run() {
                              monitorHandler.sendMessage(monitorHandler.obtainMessage());
                             }}, 
                                  200, //initialDelay
                                  200,
                                  TimeUnit.MILLISECONDS//delay                                    TimeUnit.MILLISECONDS
                         );                                                                                         
            }           
 }

 Handler monitorHandler = new Handler(){

      @Override
      public void handleMessage(Message msg) {
       startUI();
      }

 };

 void startUI(){
        Log.d("UI", "Started player UI");
        ToggleButton mStartStop;
        int currentPosition=0;
        int total=mediaPlayer.getDuration();
        TextView timer=(TextView) findViewById(R.id.timer);
        if(mediaPlayer.isPlaying())
            try {
                currentPosition = mediaPlayer
                        .getCurrentPosition();
                double seconds=currentPosition/1000;
                int time= (int) Math.round(seconds);
                String timeS=Integer.toString(time);
                timer.setText(timeS+"s");
                Log.d("position",timeS);
                fSlider.setProgress(currentPosition);
            }  catch (Exception e) {

            }
            OnSeekBarChangeListener listener = new OnSeekBarChangeListener() {
                public void onStopTrackingTouch(SeekBar seekBar) { }
                public void onStartTrackingTouch(SeekBar seekBar) { }
                public void onProgressChanged(SeekBar seekBar, 
                        int progress,
                        boolean fromUser) {
                    if(fromUser) 
                        mediaPlayer.seekTo(progress);
                }
            };
            fSlider.setOnSeekBarChangeListener(listener);

        mStartStop= (ToggleButton) findViewById(R.id.toggleButton1);
        mStartStop.setOnCheckedChangeListener(pauseListener);

 }

Answer 1

您需要在单独的线程中执行此操作，并通过runOnUiThread通过runnable发回GUI线程以设置计时器的文本。因为你可能毫无例外地设置了GUI组件的文本，我假设你现在没有这样做。

请发布完整的方法。通过完整的方法，我们可以帮助追踪它在2秒标记处停止的原因。

Android Buggy媒体播放计时器

1 个答案: