how to get seekbar to automatically move on song play?

问题

I have looked everywhere to fix my problem but i just cant seem to get it going.

How do i make seekbar automatically slide with song play ?

this is what i have so far.

ArrayList<String> arrlist = new ArrayList<String>(20);
private Handler seekHandler = new Handler();
ImageButton next, playPause, previous;
SeekBar seekBar;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout);
        getSupportActionBar().hide();

        getInit();
    }

    public void getInit() {

        songCurrentDurationLabel = (TextView) findViewById(R.id.startTime);
        songTotalDurationLabel = (TextView) findViewById(R.id.endTime);

        mediaPlayer = new MediaPlayer();
        mediaPlayer = MediaPlayer.create(this, R.raw.firstsong);

        seekBar = (SeekBar) findViewById(R.id.seekBar1);
        seekBar.setMax(mediaPlayer.getDuration());
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                // remove message Handler from updating progress bar
                seekHandler.removeCallbacks(mUpdateTimeTask);
                int totalDuration = mediaPlayer.getDuration();
                int currentPosition = progressToTimer(seekBar.getProgress(), totalDuration);

                // forward or backward to certain seconds
                mediaPlayer.seekTo(currentPosition);

                // update timer progress again
                updateProgressBar();
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
                // remove message Handler from updating progress bar
                seekHandler.removeCallbacks(mUpdateTimeTask);
            }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                if (mediaPlayer != null && fromUser) {
                    mediaPlayer.seekTo(progress);
//                   mediaPlayer.seekTo(progress * 1000);
                }
            }
        });

        spinner = ((Spinner) findViewById(R.id.spinner1));
        spinner.setAdapter(songAdapter);

        previous = ((ImageButton) findViewById(R.id.previous));
        playPause = ((ImageButton) findViewById(R.id.play));
        next = ((ImageButton) findViewById(R.id.next));

        spinner.setOnItemSelectedListener(this);
        previous.setOnClickListener(this);
        playPause.setOnClickListener(this);
        next.setOnClickListener(this);

        totalDuration = mediaPlayer.getDuration();
        currentDuration = mediaPlayer.getCurrentPosition() / 1000;

        // Displaying Total Duration time
        songTotalDurationLabel.setText("" + milliSecondsToTimer(totalDuration));

        // Displaying time completed playing
        songCurrentDurationLabel.setText("" + milliSecondsToTimer(currentDuration));
    }

    public void updateProgressBar() {
        seekHandler.postDelayed(mUpdateTimeTask, 100);
    }

    private Runnable mUpdateTimeTask = new Runnable() {
        @Override
        public void run() {
            long totalDuration = mediaPlayer.getDuration();
            long currentDuration = mediaPlayer.getCurrentPosition() / 1000;
            int progress = (int) getProgressPercentage(currentDuration, totalDuration);

            // Updating progress bar
            seekBar.setProgress(progress);

            // Running this thread after 100 milliseconds
            seekHandler.postDelayed(this, 100);
        }
    };

    public int progressToTimer(int progress, int totalDuration) {
        int currentDuration = 0;
        totalDuration = (int) (totalDuration / 1000);
        currentDuration = (int) ((((double) progress) / 100) * totalDuration);

        // return current duration in milliseconds
        return currentDuration * 1000;
    }

    public int getProgressPercentage(long currentDuration1, long totalDuration1) {
        Double percentage = (double) 0;

        long currentSeconds = (int) (currentDuration1 / 1000);
        long totalSeconds = (int) (totalDuration1 / 1000);

        // calculating percentage
        percentage = (((double) currentSeconds) / totalSeconds) * 100;

        // return percentage
        return percentage.intValue();
    }

    public String milliSecondsToTimer(long milliseconds) {
        String finalTimerString = "";
        String secondsString = "";

        // Convert total duration into time
        int hours = (int) (milliseconds / (1000 * 60 * 60));
        int minutes = (int) (milliseconds % (1000 * 60 * 60)) / (1000 * 60);
        int seconds = (int) ((milliseconds % (1000 * 60 * 60)) % (1000 * 60) / 1000);
        // Add hours if there
        if (hours > 0) {
            finalTimerString = hours + ":";
        }

        // Prepending 0 to seconds if it is one digit
        if (seconds < 10) {
            secondsString = "0" + seconds;
        } else {
            secondsString = "" + seconds;
        }

        finalTimerString = finalTimerString + minutes + ":" + secondsString;

        // return timer string
        return finalTimerString;
    }

}

I didnt include the song list and all the other stuff as i dont see why it would be necesary to put here. But anyways, when i do what i have here i dont get no error or anything, the seekbar just doesnt automatically move and when i try to move it manually to a position it goes right back to 0.

回答1:

First of all you should define a Runnable object that will be triggered each second. For your situation, in everysecond that class will be triggered.

I will paste some example code. Here is the runnable class.

Runnable timerRunnable = new Runnable() {

   public void run() {
    // Get mediaplayer time and set the value                           

    // This will trigger itself every one second.
    updateHandler.postDelayed(this, 1000);
   }
};

And you should also have a Handler that will trigger Runnable instance.

Handler updateHandler = new Handler();

updateHandler.postDelayed(timerRunnable, 1000);

I hope that sample will help you.

回答2:

I am using a Runnable and it looks like this:

private Runnable mUpdateTimeTask = new Runnable()
                                   {
                                     public void run()
                                       {
                                         long currentDuration = mediaPlayer.getCurrentPosition();
                                         long elapsedDuration = mediaPlayer.getDuration() - currentDuration;

                                         // Displaying current song progress
                                         // playing
                                         tvProgressLeft.setText("" + utils.milliSecondsToTimer(currentDuration));
                                         // Displaying remaining time
                                         tvProgressRight.setText("" + utils.milliSecondsToTimer(elapsedDuration));

                                         // Updating progress bar
                                         int progress = (int) (utils.getProgressPercentage(currentDuration,
                                             elapsedDuration));
                                         // Log.d("Progress", ""+progress);
                                         songProgressBar.setProgress(progress);

                                         // Running this thread after 100
                                         // milliseconds
                                         handler.postDelayed(this, 100);
                                       }
                                   };

/***/

But better yet here is a link to the sample that I have adopted.

http://www.androidhive.info/2012/03/android-building-audio-player-tutorial/

Regarding the tutorial the only thing that will not work is retrieving and filtering the song from the given file path. Somehow I couldn't get it to work. But I found another solution which was to write your own FileFilter and use it instead of the default File Filter.

来源：https://stackoverflow.com/questions/22621336/how-to-get-seekbar-to-automatically-move-on-song-play