package pretoct;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;   
import java.awt.event.ActionListener;   
import java.text.SimpleDateFormat;   
import java.util.Date;   
  
import javax.swing.JLabel;
import javax.swing.Timer;   
import javax.swing.JFrame;   


public class NowTime extends JFrame{
//添加 显示时间的JLabel 
    public  NowTime(){   
        JLabel time = new JLabel();   
        add(time);   
        this.setTimer(time);   
    }   
     
  
    //设置Timer 1000ms实现一次动作 实际是一个线程   
    private void setTimer(JLabel time){   
        final JLabel varTime = time;   
        Timer timeAction = new Timer(1000, new ActionListener() {          
  
            public void actionPerformed(ActionEvent e) {       
                long timemillis = System.currentTimeMillis();   
                //转换日期显示格式   
                SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");   
                varTime.setText(df.format(new Date(timemillis)));   
            }      
        });            
        timeAction.start();        
    }   
  
    //运行方法
    public static void main(String[] args) {   
    NowTime timeFrame = new NowTime(); 
    timeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    
    timeFrame.setSize(160, 80);   
    timeFrame.setLocation((int) (Toolkit.getDefaultToolkit().getScreenSize().getWidth() - timeFrame.getWidth()) / 2,
                        (int) (Toolkit.getDefaultToolkit().getScreenSize().getHeight() - timeFrame.getHeight()) / 2);//居中显示窗体
    timeFrame.setVisible(true);   
         
    }   
}