菜鸟问题，不会就别说它简单！！！！

Question

简单写的一个大部分用JBuilder生成的，呵呵
package test.org.brunt.applet;import java.awt.*;
import java.awt.event.*;
import java.applet.*;/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 1998</p>
 * <p>Company: </p>
 * @author unascribed
 * @version 1.0
 */public class DrawApplet extends Applet {
    private boolean isStandalone = false;
    private Label l = new Label();
    private int x1=0,y1=0,x2=0,y2=0;
    //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 DrawApplet() {
    }
    //Initialize the applet
    public void init() {
        try {
            jbInit();
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }
    //Component initialization
    private void jbInit() throws Exception {        this.addMouseMotionListener(new MouseMotionAdapter(){
            public void mouseDragged(MouseEvent e)
            {
                x2=e.getX();
                y2=e.getY();
                System.out.println("x2="+x2 +";y2="+y2);
                DrawApplet.this.repaint();
            }
        });
        this.addMouseListener(new MouseAdapter(){
            public void mousePressed(MouseEvent e)
            {
                x1=e.getX();
                y1=e.getY();
                System.out.println("x1="+x1 +";y1="+y1);
            }
            public void mouseReleased(MouseEvent e)
            {
                x2=e.getX();
                y2=e.getY();
                System.out.println("x2="+x2 +";y2="+y2);
            }
        });
       // this.draw
    }    public void paint(Graphics g)
    {
        super.paintComponents(g);
        //super.repaint(g);
        g.setColor(Color.yellow);
        g.drawRect(x1,y1,x2-x1,y2-y1);
        g.drawOval(x1,y1,x2-x1,y2-y1);
    }    //Get Applet information
    public String getAppletInfo() {
        return "Applet Information";
    }
    //Get parameter info
    public String[][] getParameterInfo() {
        return null;
    }
    //Main method
    public static void main(String[] args) {
        DrawApplet applet = new DrawApplet();
        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(400,320);
        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        frame.setLocation((d.width - frame.getSize().width) / 2, (d.height - frame.getSize().height) / 2);
        frame.setVisible(true);
    }
}

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.util.*;public class Test extends Frame
{
   public static void main(String[] args)
   {
      new Test();
   }
   public Test()
   {
      this.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){dispose();System.exit(0);}});
      this.setSize(300,300);
      this.setLocation(300,0);
      this.add(new Draw());
      this.show();
   }
   protected void processWindowEvent(WindowEvent event)
   {
      super.processWindowEvent(event);
      if(event.getID() == WindowEvent.WINDOW_CLOSING)
      {
         System.exit(0);
      }
   }
}
class Draw extends Canvas   //由Canvas
{
   int x1=-1;
   int y1=-1;
   int x2=-1;
   int y2=-1;
   public Draw()
   {
      this.setBackground(Color.white);
      this.addMouseListener(new MyMouseListener(this));
      this.addMouseMotionListener(new MyMouseMotionListener(this));
   }
   public void paint(Graphics g)
   {
      if(x2==-1 || y2==-1)
      {
         return;
      }
      
      g.drawOval(x1,y1,x2,y2);
     
   }
   public void update(Graphics g)
   {
      this.paint(g);
   }
}
class MyMouseListener implements MouseListener
{
   Draw draw;
   public MyMouseListener(Draw draw)
   {
      this.draw=draw;
   }
   public void mouseClicked(MouseEvent e)
   {
     
   }
   public void mouseEntered(MouseEvent e)
   {
     
   }
   public void mouseExited(MouseEvent e)
   {
     
   }
   public void mousePressed(MouseEvent e)
   {
    
      draw.x1=e.getX();
      draw.y1=e.getY();
      
      
      
   }
   public void mouseReleased(MouseEvent e)
   {
    //  draw.x2 = e.getX();
    //  draw.y2 = e.getY();
      draw.repaint();
      
   }
}
class MyMouseMotionListener implements MouseMotionListener
{
   Draw draw;
   public MyMouseMotionListener(Draw draw)
   {
      this.draw=draw;
   }
   public void mouseDragged(MouseEvent e)
   {
      draw.x2 = e.getX();
      draw.y2 = e.getY();
 
   
   }
   public void mouseMoved(MouseEvent e)
   {
      
   }
}

Answer 2

Test.html<HTML>
<HEAD>
</HEAD>
<BODY BGCOLOR="000000">
<CENTER>
<APPLET
code = "Test.class"
width = "500"
height = "300"
>
</APPLET>
</CENTER>
</BODY>
</HTML>

Answer 3

//一楼的好些，没时间了，自己看看吧
Test.javaimport java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Test extends Applet {
    private boolean isStandalone = false;
    private Label l = new Label();
    private int x1=0,y1=0,x2=0,y2=0;
  
    public String getParameter(String key, String def) {
        return isStandalone ? System.getProperty(key, def) :
            (getParameter(key) != null ? getParameter(key) : def);
    }
       public Test() {
    }
  
    public void init() {
        try {
            jbInit();
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    } 
    private void jbInit() throws Exception {        this.addMouseMotionListener(new MouseMotionAdapter(){
            public void mouseDragged(MouseEvent e)
            {
                x2=e.getX();
                y2=e.getY();
                System.out.println("x2="+x2 +";y2="+y2);
                Test.this.repaint();
            }
        });
 
        this.addMouseListener(new MouseAdapter(){
            public void mousePressed(MouseEvent e)
            {
                x1=e.getX();
                y1=e.getY();
                System.out.println("x1="+x1 +";y1="+y1);
            }
  
              public void mouseReleased(MouseEvent e)
            {
                x2=e.getX();
                y2=e.getY();
                System.out.println("x2="+x2 +";y2="+y2);
            }
        });    }
 
      public void paint(Graphics g)
    {
        super.paintComponents(g);
        g.setColor(Color.yellow);
        g.drawRect(x1,y1,x2-x1,y2-y1);
        g.drawOval(x1,y1,x2-x1,y2-y1);
    }
 
    public String getAppletInfo() {
        return "Applet Information";
    }    public String[][] getParameterInfo() {
        return null;
    }    public static void main(String[] args) {
        Test applet = new Test();
        applet.isStandalone = true;
        Frame frame;
        frame = new Frame() {
            protected void processWindowEvent(WindowEvent e) {
                super.processWindowEvent(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(400,320);
        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        frame.setLocation((d.width - frame.getSize().width) / 2, (d.height - frame.getSize().height) / 2);
        frame.setVisible(true);
    }
}