applet-----Clock

//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.text.*;
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(); 不要用了
Calendar cal = Calendar.getInstance(); //使用新库
DateFormat df = DateFormat.getDateInstance();
//String lastdate = dummy.toLocaleString();
String lastdate = df.format(cal.getTime()); //使用新方法


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;
/* 不用在使用Data类了
Date dat = new Date();
s = dat.getSeconds();
m = dat.getMinutes();
h = dat.getHours();
today = dat.toLocaleString();

*/

s = cal.get(Calendar.SECOND); //使用新库新方法
m = cal.get(Calendar.MINUTE); //使用新库新方法
h = cal.get(Calendar.HOUR); //使用新库新方法
today=df.format(cal.getTime()); //使用新库新方法

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);
}
}