example26_13.java

不错的教程 适合中高级人员的使用

import java.applet.*;
import java.awt.*;import java.util.*;
import java.awt.event.*;
class Point
{int x,y;
 Point(int x,int y)
 {this.x=x;this.y=y;
 }
}
public class Example26_13 extends Applet 
implements MouseMotionListener,MouseListener
{ int x=-1,y=-1;
   Vector v=null;int n=1;
  public void init()
 { setBackground(Color.green);
   addMouseMotionListener(this);  addMouseListener(this);
    v=new Vector(); 
 }
 public void paint(Graphics g)
 {if(x!=-1&&y!=-1)
  {  n=v.size();
    for(int i=0;i<n-1;i++)
       {Point p1=(Point)v.elementAt(i); 
        Point p2=(Point)v.elementAt(i+1); 
        g.drawLine(p1.x,p1.y,p2.x,p2.y);
       }
   }
  
 }
public void mouseDragged(MouseEvent e)
 { x=(int)e.getX();y=(int)e.getY();
   Point p=new Point(x,y);
   v.addElement(p);
   repaint();
 }
 public void mouseMoved(MouseEvent e)
  {} 
  public void mousePressed(MouseEvent e){} 
  public void mouseReleased(MouseEvent e)
{v.removeAllElements();}
  public void mouseEntered(MouseEvent e){}
  public void mouseExited(MouseEvent e){}
  public void mouseClicked(MouseEvent e){}
  public void update(Graphics g)
  { paint(g);
  } 
}