import java.awt.Color;import java.awt.Dimension;import java.awt.Font;import java.awt.Graphics;import java.awt.Graphics2D;import java.util.Calendar;import java.util.GregorianCalendar;import javax.swing.JFrame;/***1、画界面 2、绘制界面（显示静态时间） 3、调用线程刷新界面*/public class Demo extends JFrame implements Runnable{Thread clock; public Demo(){super("数字时钟"); // 调用父类的构造函数setFont(new Font("Times",Font.BOLD,60)); // 显示调用时钟的字体start();setSize(300,100);// 设置界面大小setVisible(true); // 窗口可视setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 关闭窗口的时候退出程序}public void start(){ //开始if(clock==null){clock = new Thread(this); // 实例化进程// jdk提供 一旦调用start方法，则会通过JVM找到run()方法clock.start(); // 开始进程}}// 运行进程public void run() { while(clock!=null){repaint(); // 重绘界面try {Thread.sleep(1000); // 线程暂停1000毫秒} catch (InterruptedException e) {e.printStackTrace();}}}public void paint(Graphics g){ // 重写组件的paint方法Graphics2D g2 = (Graphics2D)g; Calendar now = new GregorianCalendar(); // 提供日历的系统String timeInfo = "";int hour = now.get(Calendar.HOUR_OF_DAY); //得到小时int minute = now.get(Calendar.MINUTE);int second = now.get(Calendar.SECOND);if(hour<=9){timeInfo+="0"+hour+":";}else{timeInfo+=hour+":";}if(minute<=9){timeInfo+="0"+minute+":";}else{timeInfo+=minute+":";}if(second<=9){timeInfo+="0"+second;}else{timeInfo+=second;}g.setColor(Color.white); // 设置颜色 白色Dimension dim = getSize(); // 得到窗口大小g.fillRect(0, 0, dim.width, dim.height);g.setColor(Color.orange); // 橙色g.drawString(timeInfo, 20, 80);}// 程序的入口public static void main(String[] args){new Demo();}}
