update.java

很好得jbuilder100例源代码

package lineupdate;

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

public class update extends Applet {
  boolean flag ;
  boolean drawing ;
  Point spoint;
  Point epoint;
  boolean isStandalone = false;
  /**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 update() {
  }
  /**Initialize the applet*/
  public void init() {
    flag = false;
    drawing = false;
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  /**Component initialization*/
  private void jbInit() throws Exception {
    this.addMouseListener(new java.awt.event.MouseAdapter() {
      public void mouseClicked(MouseEvent e) {
        this_mouseClicked(e);
      }
    });
    this.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
      public void mouseMoved(MouseEvent e) {
        this_mouseMoved(e);
      }
    });
  }
  /**Get Applet information*/
  public String getAppletInfo() {
    return "Applet Information";
  }
  /**Get parameter info*/
  public String[][] getParameterInfo() {
    return null;
  }

  void this_mouseMoved(MouseEvent e) {
     if (flag){
         spoint = new Point(e.getX(),e.getY());
         flag = !flag;
     }
     else{
         epoint = new Point(e.getX(),e.getY());
         flag = !flag;
     }
     repaint();
  }

  void this_mouseClicked(MouseEvent e) {
      drawing = true;
      spoint = new Point(e.getX(),e.getY());
  }
  public void paint(Graphics g){
      if(drawing){
         g.drawLine(spoint.x,spoint.y,epoint.x,epoint.y);
      }
  }
  public void update(Graphics g){
      paint(g);
  }
  }