private TimerTask timerTask;
  private Timer timer;
  private int time = 5000;//五秒
  private int timess;
/**
   * 開始倒計時
   */
  private void startTimer() {
    timess = time/1000;
    tvTime.setText(timess+"S");
    if(timerTask==null){
      TimerTask timerTask = new TimerTask() {
        @Override
        public void run() {
          runOnUiThread(new Runnable() {
            @Override
            public void run() {
              timess--;
              tvTime.setText(timess+"S");
              btnSkipActivity();
              if(timess<=0){
                stopTimer();
                return;
              }
            }
          });
        }
      };
    }
    if(timer==null){
      timer = new Timer();
    }
    timer.schedule(timerTask, 1000, 1000);
  }
/**
   * 時間一到 ，停止倒計時
   */
  private void stopTimer(){
    if(timer!=null){
      timer.cancel();
      timer=null;
    }
    if(timerTask!=null){
      timerTask.cancel();
      timerTask=null;
    }
  }