用到CountDownTimer这个类，非常简单，只有四个方法，
public final void cancel () //取消后，再次启动会重新开始倒计时
public abstract void onFinish ()
public abstract void onTick (long millisUntilFinished) //onTick的调用是同步的，保证这次调用不会在之前调用完成前发生
public synchronized final CountDownTimer start ()
实例
1 new CountDownTimer(60 * 1000, 1000) {
2 public void onTick(long millisUntilFinished) {
3 testView.setText("seconds remaining: " + millisUntilFinished / 1000);
4 }
5 public void onFinish() {
6 testView.setText("done!");
7 }
8 }.start();
原文：http://www.cnblogs.com/WangKangReg/p/4249254.html