java窗体中显示时间，时间自动刷新。

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);

this.setLocation((int) (Toolkit.getDefaultToolkit().getScreenSize().getWidth() - this.getWidth()) / 2,

(int) (Toolkit.getDefaultToolkit().getScreenSize().getHeight() - this.getHeight()) / 2);//居中显示窗体

timeFrame.setVisible(true);

}

}