public void run() {
   if (mPlayerEngineListener != null) {
     // TODO use getCurrentPosition less frequently (usage of currentTimeMillis or
     // uptimeMillis)
     if (mCurrentMediaPlayer != null)
       mPlayerEngineListener.onTrackProgress(
           mCurrentMediaPlayer.getCurrentPosition() / 1000);
     mHandler.postDelayed(this, 1000); // 让mUpdateTimeTask延时一秒
   }
 }
 @Override
 public void rewind(int time) {
   mCurrentMediaPlayer.seekTo(mCurrentMediaPlayer.getCurrentPosition() - time);
 }
 public void forward(int time) {
   mCurrentMediaPlayer.seekTo(mCurrentMediaPlayer.getCurrentPosition() + time);
 }