clock.java

java程序

//类 Clock
import java.util.*;
import java.awt.*;
import java.applet.*;

public class Clock extends Applet implements Runnable
{
Thread timer = null;
int lastxs=0, lastys=0,
 lastxm=0, lastym=0,
 lastxh=0, lastyh=0;
Date dummy = new Date();
String lastdate = dummy.toLocaleString();

public void init()
{
int x,y;
resize(300,300);              // 设置时钟窗口大小
}

    public void paint(Graphics g)
{
int xh, yh, xm, ym, xs, ys,
s, m, h,
 xcenter, ycenter;
String today;
Date dat = new Date();//创建日期对象

s = dat.getSeconds(); //读秒数
m = dat.getMinutes(); //读分钟
h = dat.getHours();   //读小时
today = dat.toLocaleString();//把日期转为字符串
    xcenter=110;           //园中心x坐标
ycenter=55;           //园中心y坐标

// 计算出秒钟，分钟，时钟末点坐标
xs = (int)(Math.cos(s * 3.14f/30 - 3.14f/2) * 45 + xcenter);
ys = (int)(Math.sin(s * 3.14f/30 - 3.14f/2) * 45 + ycenter);
xm = (int)(Math.cos(m * 3.14f/30 - 3.14f/2) * 40 + xcenter);
ym = (int)(Math.sin(m * 3.14f/30 - 3.14f/2) * 40 + ycenter);
xh = (int)(Math.cos((h*30 + m/2) * 3.14f/180 - 3.14f/2) * 30 + xcenter);
yh = (int)(Math.sin((h*30 + m/2) * 3.14f/180 - 3.14f/2) * 30 + ycenter);

// 画出表盘
g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
g.setColor(Color.blue);
g.drawOval(xcenter-50,ycenter-50,100,100);
g.setColor(Color.darkGray);
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);

//如果当前秒钟，分钟，时钟末点坐标与上次不一样，
    //则先擦掉原来显示的秒钟，分钟，时钟和日期
g.setColor(getBackground());

//如果秒数发生变化，则擦除原来的秒针和原来的日期
    if (xs != lastxs || ys != lastys)
{
    g.drawLine(xcenter, ycenter, lastxs, lastys);
    g.drawString(lastdate, 5, 125);
}

//如果分钟数发生变化，则擦除原来的分针和原来的日期
if (xm != lastxm || ym != lastym)
{
    g.drawLine(xcenter, ycenter-1, lastxm, lastym);
    g.drawLine(xcenter-1, ycenter, lastxm, lastym);
}

//如果小时数发生变化，则擦除原来的时针和原来的日期
    if (xh != lastxh || yh != lastyh)
{
    g.drawLine(xcenter, ycenter-1, lastxh, lastyh);
    g.drawLine(xcenter-1, ycenter, lastxh, lastyh);
}
  
    //在新的位置重画秒钟，分钟，时钟和日期
g.setColor(Color.darkGray);
g.drawString(today, 5, 125);  
g.drawLine(xcenter, ycenter, xs, ys);
g.setColor(Color.blue);
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);

    //更新秒钟，分钟，时钟线的坐标和日期字符串
    lastxs=xs; lastys=ys;
lastxm=xm; lastym=ym;
lastxh=xh; lastyh=yh;
lastdate = today;
}

public void start()
{
if(timer == null)
{
      timer = new Thread(this);//创建线程
      timer.start();           //线程开始运行
}
}

public void stop()
{
    timer = null;
}

public void run()
{
while (timer != null)
{
    try {Thread.sleep(100);} catch (InterruptedException e){}
    repaint();
}
timer = null;
}

public void update(Graphics g)
{
    paint(g);
}
}