jdk中有现成的例子 !你看看就应该知道了
给你一段代码:
mport java.util.*;
import java.awt.*;
import java.applet.*;
import java.text.*;
/**
* Time!
*
* @author Rachel Gollub
* @modified Daniel Peek replaced circle drawing calculation, few more changes
*/
public class Clock extends Applet implements Runnable {
private volatile Thread timer;
// The thread that displays clock
private int lastxs, lastys, lastxm,
lastym, lastxh, lastyh;
// Dimensions used to draw hands
private SimpleDateFormat formatter;
// Formats the date displayed
private String lastdate;
// String to hold date displayed
private Font clockFaceFont;
// Font for number display on clock
private Date currentDate;
// Used to get date to display
private Color handColor;
// Color of main hands and dial
private Color numberColor;
// Color of second hand and numbers
private int xcenter = 80, ycenter = 55;
// Center position
public void init() {
int x,y;
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;
try {
setBackground(new Color(Integer.parseInt(getParameter("bgcolor"
,
16)));
} catch (NullPointerException e) {
} catch (NumberFormatException e) {
}
try {
handColor = new Color(Integer.parseInt(getParameter("fgcolor1"
,
16));
} catch (NullPointerException e) {
} catch (NumberFormatException e) {
}
try {
numberColor = new Color(Integer.parseInt(getParameter("fgcolor2"
,
16));
} catch (NullPointerException e) {
} catch (NumberFormatException e) {
}
resize(300,300);
// Set clock window size
}
// Paint is the main part of the program
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);
// Get the date to print at the bottom
formatter.applyPattern("EEE MMM dd HH:mm:ss yyyy"
;
today = formatter.format(currentDate);
g.setFont(clockFaceFont);
// Erase if necessary
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);
}
// Draw date and hands
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;
}
public void paint(Graphics g) {
g.setFont(clockFaceFont);
// Draw the circle and numbers
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);
// Draw date and hands
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) {
}
repaint();
}
}
public String getAppletInfo() {
return "Title: A Clock /n"
+ "Author: Rachel Gollub, 1995 /n"
+ "An analog clock.";
}
public String[][] getParameterInfo() {
String[][] info = {
{"bgcolor", "hexadecimal RGB number",
"The background color. Default is the color of your browser."},
{"fgcolor1", "hexadecimal RGB number",
"The color of the hands and dial. Default is blue."},
{"fgcolor2", "hexadecimal RGB number",
"The color of the second hand and numbers. Default is dark gray."}
};
return info;
}
}
]