//sleep模拟网络延迟：

public class hh implements Runnable {public static void main(String[]args) throws InterruptedException{ Date date=new Date(System.currentTimeMillis()+1000*10);//当前时间加10秒 long endTime=date.getTime(); while(true) { System.out.println(new SimpleDateFormat("mm:ss").format(date));//以分:秒的形式输出 Thread.sleep(1000); date=new Date(date.getTime()-1000); if(endTime-1000*10>date.getTime()) { break; } }}public static void test() throws InterruptedException{ int num=10; while(true) { Thread.sleep(1000); System.out.println(num--); }}}