clock2.java

一个用java applet编写的时钟程序,可以用ie直接打开运行

/* 
//保存为Clock2.java 
//编译: javac Clock2.java 
//在本目录下新建一个记事本,保存为html的网页文件,内容为<applet code="Clock2.class" width=200 height=150></applet> 
//最后打开该网页 
*/ 
import java.util.*; 
import java.awt.*; 
import java.applet.*; 
public class Clock2 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); // Set clock window size 
    } 
    // Plotpoints allows calculation to only cover 45 degrees of the circle, 
    // and then mirror 
    public void plotpoints(int x0, int y0, int x, int y, Graphics g) 
    {
        g.drawLine(x0+x,y0+y,x0+x,y0+y); 
        g.drawLine(x0+y,y0+x,x0+y,y0+x); 
        g.drawLine(x0+y,y0-x,x0+y,y0-x); 
        g.drawLine(x0+x,y0-y,x0+x,y0-y); 
        g.drawLine(x0-x,y0-y,x0-x,y0-y); 
        g.drawLine(x0-y,y0-x,x0-y,y0-x); 
        g.drawLine(x0-y,y0+x,x0-y,y0+x); 
        g.drawLine(x0-x,y0+y,x0-x,y0+y); 
    } 
    // Circle is just Bresenham′s algorithm for a scan converted circle 
    public void circle(int x0, int y0, int r, Graphics g) 
    {
        int x,y; 
        float d; 
        x=0; 
        y=r; 
        d=5/4-r; 
        plotpoints(x0,y0,x,y,g); 
        while (y>x)
        {
            if (d<0) 
            {
                d=d+2*x+3; 
                x++; 
            } 
            else 
            {
                d=d+2*(x-y)+5; 
                x++; 
                y--; 
            } 
            plotpoints(x0,y0,x,y,g); 
        } 
    } 
    // Paint is the main part of the program 
    public void paint(Graphics g) 
    {
        int xh, yh, xm, ym, xs, ys, s, m, h, xcenter, ycenter; 
        String today; 
        Date dat = new Date(); 
        s = dat.getSeconds(); 
        m = dat.getMinutes(); 
        h = dat.getHours(); 
        today = dat.toLocaleString(); 
        xcenter=80; 
        ycenter=55; 
        // a= s* pi/2 - pi/2 (to switch 0,0 from 3:00 to 12:00) 
        // x = r(cos a) + xcenter, y = r(sin a) + ycenter 
        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); 
        // Draw the circle and numbers 
        g.setFont(new Font("TimesRoman", Font.PLAIN, 14)); 
        g.setColor(Color.blue); 
        circle(xcenter,ycenter,50,g); 
        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); 
        // Erase if necessary, and redraw 
        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(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); 
        lastxs=xs; lastys=ys; 
        lastxm=xm; lastym=ym; 
        lastxh=xh; lastyh=yh; 
        lastdate = today; 
    } 
    public void start() 
    {
        if(timer == null) 
        {
            timer = new Thread(this); 
            timer.start(); 
        } 
    } 
    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); 
    } 
}