clock.java

Java实例入门

package appletclock;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;
import java.text.*;

/**
 * Title:        使用Applet完成的时钟
 * Description:
 * Copyright:    Copyright (c) 2001
 * Company:
 * @author
 * @version 1.0
 */

public class clock extends Applet implements Runnable {
  boolean isStandalone = false;
  String bgcolor;
  String fgcolor1;
  String fgcolor2;
  Thread timer;                // The thread that displays clock
  int lastxs, lastys, lastxm,
      lastym, lastxh, lastyh;  // Dimensions used to draw hands
  SimpleDateFormat formatter;  // Formats the date displayed
  String lastdate;             // String to hold date displayed
  Font clockFaceFont;          // Font for number display on clock
  Date currentDate;            // Used to get date to display
  Color handColor;             // Color of main hands and dial
  Color numberColor;           // Color of second hand and numbers
  /**Get a parameter value*/
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }

  /**Construct the applet*/
  public clock() {
  }
  /**Initialize the applet*/
  public void init() {
    try {
      bgcolor = this.getParameter("bgcolor", "000000");
    }
    catch(Exception e) {
      e.printStackTrace();
    }
    try {
      fgcolor1 = this.getParameter("fgcolor1", "ff0000");
    }
    catch(Exception e) {
      e.printStackTrace();
    }
    try {
      fgcolor2 = this.getParameter("fgcolor2", "ff00ff");
    }
    catch(Exception e) {
      e.printStackTrace();
    }
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }

  }
  /**Component initialization*/
  private void jbInit() throws Exception {
   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 (Exception E) { }
        try {
            handColor = new Color(Integer.parseInt(getParameter("fgcolor1"),16));
        } catch (Exception E) { }
        try {
            numberColor = new Color(Integer.parseInt(getParameter("fgcolor2"),16));
        } catch (Exception E) { }
        resize(200,150);              // Set clock window size
  }
  /**Start the applet*/
  public void start() {
      timer = new Thread(this);
      timer.start();
  }
  /**Stop the applet*/
  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 void update(Graphics g) {
        paint(g);
 }
   // Paint is the main part of the program
 public void paint(Graphics g) {
     int xh, yh, xm, ym, xs, ys, s = 0, m = 10, h = 10, xcenter, ycenter;
     String today;

     currentDate = new Date();
     SimpleDateFormat formatter = new SimpleDateFormat("s",Locale.getDefault());
     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;
     }
     formatter.applyPattern("EEE MMM dd HH:mm:ss yyyy");
     today = formatter.format(currentDate);
     xcenter=100;
     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(clockFaceFont);
     g.setColor(handColor);
     circle(xcenter,ycenter,50,g);
     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);

    // 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(numberColor);
          g.drawString("", 5, 125);
          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;
  }
  /**Destroy the applet*/
  public void destroy() {
  }

  /**Get Applet information*/
  public String getAppletInfo() {
    return "Applet Information:an Applet clock";
  }
  /**Get parameter info*/
  public String[][] getParameterInfo() {
    String[][] pinfo =
      {
      {"bgcolor", "String", ""},
      {"fgcolor1", "String", ""},
      {"fgcolor2", "String", ""},
      };
    return pinfo;
  }

  // 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) {
//       g.drawArc(x0-r,y0-r,2*r,2*r,0,360);
      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);
      }
    }
  /**Main method*/
  public static void main(String[] args) {
    clock applet = new clock();
    applet.isStandalone = true;
    Frame frame;
    frame = new Frame() {
      protected void processWindowEvent(WindowEvent e) {
        super.processWindowEvent(e);
        if (e.getID() == WindowEvent.WINDOW_CLOSING) {
          System.exit(0);
        }
      }
      public synchronized void setTitle(String title) {
        super.setTitle(title);
        enableEvents(AWTEvent.WINDOW_EVENT_MASK);
      }
    };
    frame.setTitle("Applet Frame");
    frame.add(applet, BorderLayout.CENTER);
    applet.init();
    applet.start();
    frame.setSize(170,170);
    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    frame.setLocation((d.width - frame.getSize().width) / 2, (d.height - frame.getSize().height) / 2);
    frame.setVisible(true);
  }
}