clock.java~1~

《Java课程设计案例精编（第二版）》-黄晓东-源代码-4450

package manpowersystem;

import java.util.*;
import java.awt.*;
import javax.swing.*;

public class Clock extends JPanel implements Runnable {

  boolean keepRunning=true;
  int lastxs=0, lastys=0, lastxm=0, lastym=0, lastxh=0, lastyh=0;
  Date dummy = new Date();
  String lastdate = dummy.toLocaleString();
  String myName;

  public Clock(String inName) {
     myName=new String(inName);
  }

  // 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 paintComponent(Graphics g) {
  super.paintComponent(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=getWidth()/2;
  ycenter=getHeight()/2-10;

  // 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) * 35 + xcenter);
  ys = (int)(Math.sin(s * 3.14f/30 - 3.14f/2) * 35 + ycenter);
  xm = (int)(Math.cos(m * 3.14f/30 - 3.14f/2) * 30 + xcenter);
  ym = (int)(Math.sin(m * 3.14f/30 - 3.14f/2) * 30 + ycenter);
  xh = (int)(Math.cos((h*30 + m/2) * 3.14f/180 - 3.14f/2) * 20 + xcenter);
  yh = (int)(Math.sin((h*30 + m/2) * 3.14f/180 - 3.14f/2) * 20 + ycenter);

  // Draw the circle and numbers

  g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
  g.setColor(Color.green);
  circle(xcenter,ycenter,40,g);
  g.setColor(new Color(0,0,200));
  g.drawString("9",xcenter-35,ycenter+3);
  g.drawString("3",xcenter+30,ycenter+3);
  g.drawString("12",xcenter-5,ycenter-27);
  g.drawString("6",xcenter-3,ycenter+35);

  // Erase if necessary, and redraw

  g.setColor(Color.red);
  if (xs != lastxs || ys != lastys) {
    g.drawLine(xcenter, ycenter, lastxs, lastys);
    g.drawString(lastdate,xcenter-55, ycenter+55);
  }
  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.red);
  g.drawString(today, xcenter-55, ycenter+55);
  g.drawLine(xcenter, ycenter, xs, ys);
  g.setColor(Color.black);
  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 stop() {
  keepRunning= false;
}

public void run() {
  while (keepRunning) {
    try {Thread.sleep(100);} catch (InterruptedException e){}
    repaint();
  }
}

}