CountDownTimer_countdowntimer暂停

CountDownTimer (long millisInFuture, long countDownInterval)
参数1，设置倒计时的总时间（毫秒）
参数2，设置每次减去多少毫秒

    private Button btn;
private TextView vertifyView;  
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initView();
}
private void initView(){
vertifyView =(TextView) findViewById(R.id.vertifyView);
btn =(Button) findViewById(R.id.button);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//1,请求后台...
//2,触发定时器刷新UI（启动代码最好放在请求后台回调成功之后）
timer.start();
}
});
}
private CountDownTimer timer = new CountDownTimer(10000, 1000) {  
@Override  
public void onTick(long millisUntilFinished) {  
vertifyView.setText((millisUntilFinished / 1000) + "秒后可重发");  
}  
@Override  
public void onFinish() {  
vertifyView.setEnabled(true);  
vertifyView.setText("获取验证码");  
}  
};  

public abstract class CountDownTimer { 

/** * Millis since epoch when alarm should stop. */
private final long mMillisInFuture;
/** * The interval in millis that the user receives callbacks */
private final long mCountdownInterval;
private long mStopTimeInFuture;
/** * boolean representing if the timer was cancelled */
private boolean mCancelled = false;
/** * @param millisInFuture The number of millis in the future from the call * to {@link #start()} until the countdown is done and {@link #onFinish()} * is called. * @param countDownInterval The interval along the way to receive * {@link #onTick(long)} callbacks. */
public CountDownTimer(long millisInFuture, long countDownInterval) {
mMillisInFuture = millisInFuture;
mCountdownInterval = countDownInterval;
}
/** * Cancel the countdown. */
public synchronized final void cancel() {
mCancelled = true;
mHandler.removeMessages(MSG);
}
/** * Start the countdown. */
public synchronized final CountDownTimer start() {
mCancelled = false;
if (mMillisInFuture <= 0) {
onFinish();
return this;
}
mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
mHandler.sendMessage(mHandler.obtainMessage(MSG));
return this;
}
/** * Callback fired on regular interval. * @param millisUntilFinished The amount of time until finished. */
public abstract void onTick(long millisUntilFinished);
/** * Callback fired when the time is up. */
public abstract void onFinish();
private static final int MSG = 1;
// handles counting down
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
synchronized (CountDownTimer.this) {
if (mCancelled) {
return;
}
final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();
if (millisLeft <= 0) {
onFinish();
} else if (millisLeft < mCountdownInterval) {
// 剩余时间小于一次时间间隔的时候，不再通知，只是延迟一下
sendMessageDelayed(obtainMessage(MSG), millisLeft);
} else {
long lastTickStart = SystemClock.elapsedRealtime();
onTick(millisLeft);
// 处理用户onTick执行的时间
long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();
// 特殊情况：用户的onTick方法花费的时间比interval长，那么直接跳转到下一次interval
while (delay < 0) delay += mCountdownInterval;
sendMessageDelayed(obtainMessage(MSG), delay);
}
}
}
};
}

sendMessageDelayed(obtainMessage(MSG), delay);

onTick(millisLeft);

vertifyView.setText((millisUntilFinished / 1000) + "秒后可重发"); 

activity中
if(!activity.isFinishing()){
//doing something...
}
fragment中
if(getActivity()!=null){
//doing something...
}

    @Override
public void onFinish() {
if(getFragmentManager()!=null){
dismiss();
}
}

@Override
public void onDestroy() {
if(timer!=null){
timer.cancel();
timer = null;
}
super.onDestroy();
}