applet实现时钟程序_编写多线程的applet小程序类clock,实现数字时钟功能

   java 因applet而兴起，而今他却成了鸡肋。近期看了下jdk，在jdk1.6中applet还是在更新，相信还是有一定的用武之地。

 

   利用applet实现时钟，挺不错的一段小程序，大家先来看看运行的效果图：

                                        

 

 

实现思路：

           

          利用awt中的绘图程序实现，结合多线程动态更新时间

 

         代码如下：

 

               （参考jdk中clock）

 

       import java.util.*;
import java.awt.*;
import java.applet.*;
import java.text.*;

/**
 * Current Time
 *
 * @author softeem-sunhn
 *
 */
public class Clock extends Applet implements Runnable {
    private volatile Thread timer;       // 显示时钟的线程
    private int lastxs, lastys, lastxm,
                lastym, lastxh, lastyh;  // 时间
    private SimpleDateFormat formatter;  // 格式化时间
    private String lastdate;            
    private Font clockFaceFont;          // 时钟数字颜色
    private Date currentDate;            // 当前时间
    private Color handColor;             // 表盘数字颜色
    private Color numberColor;           // 数字变化后颜色
    private int xcenter = 80, ycenter = 55; // 圆心定位

    public void init() {
        lastxs = lastys = lastxm = lastym = lastxh = lastyh = 0;
        formatter = new SimpleDateFormat ("EEE MMM dd hh:mm:ss yyyy",
                                          Locale.getDefault());
        currentDate = new Date();
        lastdate = formatter.format(currentDate);
        clockFaceFont = new Font("Serif", Font.PLAIN, 14);
        handColor = Color.blue;
        numberColor = Color.darkGray;
    }

    // 重新绘钟表图
    @Override
    public void update(Graphics g) {
        int xh, yh, xm, ym, xs, ys;
        int s = 0, m = 10, h = 10;
        String today;

        currentDate = new Date();
       
        formatter.applyPattern("s");
        try {
            s = Integer.parseInt(formatter.format(currentDate));
        } catch (NumberFormatException n) {
            s = 0;
        }
        formatter.applyPattern("m");
        try {
            m = Integer.parseInt(formatter.format(currentDate));
        } catch (NumberFormatException n) {
            m = 10;
        }   
        formatter.applyPattern("h");
        try {
            h = Integer.parseInt(formatter.format(currentDate));
        } catch (NumberFormatException n) {
            h = 10;
        }
   
        // Set position of the ends of the hands
        xs = (int) (Math.cos(s * Math.PI / 30 - Math.PI / 2) * 45 + xcenter);
        ys = (int) (Math.sin(s * Math.PI / 30 - Math.PI / 2) * 45 + ycenter);
        xm = (int) (Math.cos(m * Math.PI / 30 - Math.PI / 2) * 40 + xcenter);
        ym = (int) (Math.sin(m * Math.PI / 30 - Math.PI / 2) * 40 + ycenter);
        xh = (int) (Math.cos((h*30 + m / 2) * Math.PI / 180 - Math.PI / 2) * 30
                   + xcenter);
        yh = (int) (Math.sin((h*30 + m / 2) * Math.PI / 180 - Math.PI / 2) * 30
                   + ycenter);
   
        formatter.applyPattern("EEE MMM dd HH:mm:ss yyyy");
        today = formatter.format(currentDate);

        g.setFont(clockFaceFont);

        g.setColor(getBackground());
        if (xs != lastxs || ys != lastys) {
            g.drawLine(xcenter, ycenter, lastxs, lastys);
            g.drawString(lastdate, 5, 125);
        }
        if (xm != lastxm || ym != lastym) {
            g.drawLine(xcenter, ycenter-1, lastxm, lastym);
            g.drawLine(xcenter-1, ycenter, lastxm, lastym);
        }
        if (xh != lastxh || yh != lastyh) {
            g.drawLine(xcenter, ycenter-1, lastxh, lastyh);
            g.drawLine(xcenter-1, ycenter, lastxh, lastyh);
        }

        g.setColor(numberColor);
        g.drawString(today, 5, 125);   
        g.drawLine(xcenter, ycenter, xs, ys);
        g.setColor(handColor);
        g.drawLine(xcenter, ycenter-1, xm, ym);
        g.drawLine(xcenter-1, ycenter, xm, ym);
        g.drawLine(xcenter, ycenter-1, xh, yh);
        g.drawLine(xcenter-1, ycenter, xh, yh);
        lastxs = xs; lastys = ys;
        lastxm = xm; lastym = ym;
        lastxh = xh; lastyh = yh;
        lastdate = today;
        currentDate = null;
    }
    @Override
    public void paint(Graphics g) {
        g.setFont(clockFaceFont);
        // 绘画表盘及数字
        g.setColor(handColor);
        g.drawArc(xcenter-50, ycenter-50, 100, 100, 0, 360);
        g.setColor(numberColor);
        g.drawString("9", xcenter-45, ycenter+3);
        g.drawString("3", xcenter+40, ycenter+3);
        g.drawString("12", xcenter-5, ycenter-37);
        g.drawString("6", xcenter-3, ycenter+45);

        // 绘画时间
        g.setColor(numberColor);
        g.drawString(lastdate, 5, 125);   
        g.drawLine(xcenter, ycenter, lastxs, lastys);
        g.setColor(handColor);
        g.drawLine(xcenter, ycenter-1, lastxm, lastym);
        g.drawLine(xcenter-1, ycenter, lastxm, lastym);
        g.drawLine(xcenter, ycenter-1, lastxh, lastyh);
        g.drawLine(xcenter-1, ycenter, lastxh, lastyh);
    }

    public void start() {
        timer = new Thread(this);
        timer.start();
    }

    public void stop() {
        timer = null;
    }
    public void run() {
        Thread me = Thread.currentThread();
        while (timer == me) {
            try {
                Thread.currentThread().sleep(100);
            } catch (InterruptedException e) {
            }
            // 负责隔一段时间调用 paint() 与  update() 参见 jdk  repaint()
            repaint();
        }
    }
    // 测试方法
    public static void main(String[] args) {
  Thread t = new Thread(new Clock());
  t.start();
 }
}