验证码-jsp

1、产生验证码jsp代码

<%@ page contentType="image/jpeg" language="java" import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" pageEncoding="utf-8"%>  
  
<%!  
    Color getRandColor(int fc,int bc){  
        Random random = new Random();  
        if(fc > 255){  
            fc = 255;  
        }  
        if(bc < 255){  
            bc = 255;  
        }  
        int r = fc +random.nextInt(bc-fc);  
        int g = fc +random.nextInt(bc-fc);  
        int b = fc +random.nextInt(bc-fc);  
          
          
        return new Color(r,g,b);  
    }  
%>  
  
<%   
    //设置页面不缓存  
    response.setHeader("Pragma","no-cache");  
    response.setHeader("Cache-Control","no-catch");  
    response.setDateHeader("Expires",0);  
      
    //在内存中创建图象  
    int width = 60;  
    int height = 20;  
    BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);  
      
    //创建图象  
    Graphics g = image.getGraphics();  
    //生成随机对象  
    Random random = new Random();  
    //设置背景色  
    g.setColor(getRandColor(200,250));  
    g.fillRect(0,0,width,height);  
    //设置字体  
    g.setFont(new Font("Tines Nev Roman",Font.PLAIN,18));  
    //随机产生干扰线  
    g.setColor(getRandColor(160,200));  
    for(int i = 0; i < 255; i++){  
        int x = random.nextInt(width);  
        int y = random.nextInt(height);  
        int xl = random.nextInt(12);  
        int yl = random.nextInt(12);  
    }  
    //随机产生认证码,4位
    String ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; 
    String sRand = "";  
    for(int i = 0; i < 4; i++){  
        String rand = String.valueOf(ch.charAt(random.nextInt(ch.length())));  
        sRand  += rand;  
        //将认证码显示到图象中  
        g.setColor(new Color(20 + random.nextInt(110),20 + random.nextInt(110),20 + random.nextInt(110)));  
        g.drawString(rand,13*i+6,16);  
    }  
    //验证码存到session中,key=rCode
    session.setAttribute("rCode",sRand);  
    //图像生效  
    g.dispose();  
    //输出图像到页面  
    ImageIO.write(image,"JPEG",response.getOutputStream());  
    out.clear();  
    out = pageContext.pushBody();  
%>

2、显示验证码jsp代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script>
    function reImg()
    {
        document.getElementById("img").src="number.jsp?code=" + Math.random();
    }
</script>
</head>
<body>
<img src="number.jsp" id="img" onclick="reImg()"/>
</body>
</html>