mousetracker.java

演示了处理鼠标事件的基本作法

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class MouseTracker extends Applet
             implements MouseListener,MouseMotionListener
{
   int xPos,yPos=-10;
   String s="";
   int d=3;
   public void init()
   {
      addMouseListener(this);
      addMouseMotionListener(this);
    }
    public void paint(Graphics g)
    {
     if(s.equals("Dragging"))
       g.fillOval(xPos,yPos,d,d);
     if(s.equals("Clicked"))
     {
        g.setColor(Color.red);
        g.drawLine(xPos-d,yPos,xPos+d,yPos);
        g.drawLine(xPos,yPos-d,xPos,yPos+d);
      }
      else g.setColor(Color.black);
 }
 public void update(Graphics g)
 {
   paint(g);
  }
  private void setValues(String event,int x,int y)
  {
       s=event;
       xPos=x;
       yPos=y;
       repaint();
   }
   
   public void mouseClicked(MouseEvent e)
   {
      setValues("Clicked",e.getX(),e.getY());
    }

    public void mousePressed(MouseEvent e)        //44
    {
      setValues("Pressed",e.getX(),e.getY());
    }

    public void mouseReleased(MouseEvent e)
   {
      setValues("Released",e.getX(),e.getY());
    }

    public void mouseEntered(MouseEvent e)
   {
      showStatus("Mouse in applet area");
    }

    public void mouseExited(MouseEvent e)
   {
      showStatus("Mouse outside applet area");
    }

    public void mouseDragged(MouseEvent e)
   {
      setValues("Dragging",e.getX(),e.getY());
    }

     public void mouseMoved(MouseEvent e)
   {
      setValues("Moving",e.getX(),e.getY());
    }
}