用JAVA做一个时钟程序

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Calendar;
import java.util.GregorianCalendar;

import javax.swing.JFrame;
import javax.swing.JPanel;
/**
 * 时间类
 * *
 */
public class Clock extends JFrame {
    /**
     *
     */
    private static final long serialVersionUID = 1L;

    public Clock() {
        ClockPaint cp = new ClockPaint(20, 20, 70);

        this.add(cp);
        this.setSize(200, 200);
        this.setResizable(false);
        this.setLocation(260, 120);
        this.setTitle("小时钟");
        this.setVisible(true);
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }

    public static void main(String[] s) {
        new Clock();
    }
}

class ClockPaint extends JPanel implements Runnable {
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    int x, y, r;
    int h, m, s;// 小时，分钟，秒
    double rad = Math.PI / 180;

    public ClockPaint(int x, int y, int r) {
        this.x = x;
        this.y = y;
        this.r = r;
        Calendar now = new GregorianCalendar();
        s = now.get(Calendar.SECOND) * 6;// 获得秒转换成度数
        m = now.get(Calendar.MINUTE) * 6;// 获得分钟
        h = (now.get(Calendar.HOUR_OF_DAY) - 12) * 30
                + now.get(Calendar.MINUTE) / 12 * 6;// 获得小时

        Thread t = new Thread(this);
        t.start();
    }

    public void paint(Graphics g) {
        // 清屏
        super.paint(g);
        g.setColor(Color.BLACK);
        g.fillRect(0, 0, r * 3, r * 3);
        // 画圆
        g.setColor(Color.WHITE);
        g.drawOval(x, y, r * 2, r * 2);
        // 秒针
        g.setColor(Color.RED);
        int x1 = (int) ((r - 10) * Math.sin(rad * s));
        int y1 = (int) ((r - 10) * Math.cos(rad * s));
        g.drawLine(x + r, y + r, x + r + x1, y + r - y1);
        // 分针
        g.setColor(Color.BLUE);
        x1 = (int) ((r - r / 2.5) * Math.sin(rad * m));
        y1 = (int) ((r - r / 2.5) * Math.cos(rad * m));
        g.drawLine(x + r, y + r, x + r + x1, y + r - y1);
        // 时针
        g.setColor(Color.CYAN);
        x1 = (int) ((r - r / 1.5) * Math.sin(rad * h));
        y1 = (int) ((r - r / 1.5) * Math.cos(rad * h));
        g.drawLine(x + r, y + r, x + r + x1, y + r - y1);
        // 数字
        g.setColor(Color.YELLOW);
        int d = 29;
        for (int i = 1; i <= 12; i++) {
            x1 = (int) ((r - 10) * Math.sin(rad * d));
            y1 = (int) ((r - 10) * Math.cos(rad * d));
            g.drawString(i + "", x + r + x1 - 4, x + r - y1 + 5);
            d += 30;
        }
        // 小点
        d = 0;
        for (int i = 0; i < 60; i++) {
            x1 = (int) ((r - 2) * Math.sin(rad * d));
            y1 = (int) ((r - 2) * Math.cos(rad * d));
            g.drawString(".", x + r + x1 - 1, x + r - y1 + 1);
            d += 6;
        }
        // 显示时间
        //Calendar now1 = new GregorianCalendar();
        //g.drawString(now1.get(Calendar.HOUR_OF_DAY) + "："
                //+ now1.get(Calendar.MINUTE) + "：" + now1.get(Calendar.SECOND),
                //0, 10);

    }

    public void run() {
        while (true) {
            try {
                Thread.sleep(1000);
            } catch (Exception ex) {
            }
            s += 6;
            if (s >= 360) {
                s = 0;
                m += 6;
                if (m == 72 || m == 144 || m == 216 || m == 288) {
                    h += 6;
                }
                if (m >= 360) {
                    m = 0;
                    h += 6;
                }
                if (h >= 360) {
                    h = 0;
                }
            }
            this.repaint();
        }
    }
}