<%@ page contentType="image/jpeg; charset=utf-8" 
  language="java" import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" 
  pageEncoding="UTF-8"%> 
   
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
 
 
 
  
  
  
  
  
  
  
   
  
  
 
  
 
  
  <%! 
   //获取随机颜色 
   public Color getColor(){ 
    Random random = new Random(); 
    //使用rgb()随机产生颜色 
    int r = random.nextInt(256); 
    int g = random.nextInt(256); 
    int b = random.nextInt(256); 
     
    return new Color(r,g,b); 
   } 
    
   //获取随机数字 产生一个4位数 
   public String getNum(){ 
    String str = ""; 
    Random random = new Random(); 
    for(int i = 0;i < 4;i++){ 
     str += random.nextInt(10); //0-9 
    } 
    return str; 
   } 
   %> 
   
   <% 
   /* 清除缓存 */ 
   response.setHeader("pragma", "mo-cache"); 
   response.setHeader("cache-control", "no-cache"); 
   response.setDateHeader("expires", 0); 
   //产生矩形框 
   BufferedImage image = new BufferedImage(80,30,BufferedImage.TYPE_INT_RGB); 
   //获取画笔工具 
   Graphics g = image.getGraphics(); 
   //设置矩形框的颜色 
   g.setColor(new Color(200,200,200)); 
   //设置坐标和宽高 
   g.fillRect(0, 0, 80, 30); 
    
   //随机产生干扰线 
   for(int i = 0;i < 30;i++){ 
    Random random = new Random(); 
    int x = random.nextInt(80); 
    int y = random.nextInt(30); 
    int x1 = random.nextInt(x + 10); 
    int y1 = random.nextInt(y + 10); 
    //设置随机颜色 
    g.setColor(getColor()); 
    //画出来 
    g.drawLine(x, y, x1, y1); 
   } 
    
   //字的颜色和数字 
   g.setFont(new Font("Microsoft YaHei",Font.BOLD,16)); 
   g.setColor(Color.BLACK); 
   //获取随机数字 
   String checkNum = getNum(); 
    
   //给字拼接空格 
   StringBuffer sb = new StringBuffer(); 
   for(int i = 0;i < checkNum.length();i++){ 
    sb.append(checkNum.charAt(i) + " "); 
   } 
   //画出数字 
   g.drawString(sb.toString(), 15, 20); 
   //存入session域中 
   session.setAttribute("CHECKNUM", checkNum); //例如1010 
   //将图像以jpeg的形式通过字节流输出 
   ImageIO.write(image, "jpeg", response.getOutputStream()); 
   //清除缓存 
   out.clear(); 
   //放入body中 
   out = pageContext.pushBody(); 
   %>