import java.awt.*;    
import java.awt.event.*;    
import javax.swing.*;    
import java.util.*;    
public class DigitalClockTest{    
        public static void main(String[] args){    
                JFrame jf = new JFrame("Digital Clock");    
                JLabel jlblClock = new JLabel("time");    
                
                jlblClock.setHorizontalAlignment(JLabel.CENTER);//设置Label中文件居中显示    
                jf.add(jlblClock,"Center");    
                jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    
                jf.setLocationByPlatform(true);    
                jf.pack();    
                jf.setVisible(true);    
                
                MyThread mt = new MyThread(jlblClock);    
                mt.start();    
        }    
}    
class MyThread extends Thread{    
        private JLabel clock;    
        
        //得到当前的时期和时间    
        public String getTime(){    
                Calendar c = new GregorianCalendar();    
                String time = c.get(Calendar.YEAR)+"/"+(c.get(Calendar.MONTH)+1)+"/"+c.get(Calendar.DATE)+" ";    
                int h = c.get(Calendar.HOUR_OF_DAY);    
                int m = c.get(Calendar.MINUTE);    
                int s = c.get(Calendar.SECOND);    
                String ph = h<10 ? "0":"";    
                String pm = m<10 ? "0":"";    
                String ps = s<10 ? "0":"";    
                time+= ph+h+":"+pm+m+":"+ps+s;    
                return time;    
        }    
        //将日期和时间显示在lable上面并设置 1 秒刷新一次    
        public MyThread(JLabel clock){    
                this.clock = clock;    
        }    
        @Override    
        public void run(){    
                while(true){    
                        clock.setText(this.getTime());    
                        try{    
                                Thread.sleep(1000);//设置时间间隔为1000ms    
                        }    
                        catch(Exception e){    
                                System.out.println(e);    
                        }    
                }    
        }    
}