java验证码

①servlet代码绘画验证码图片

package com.util.servlet;

import java.awt.Color;  
import java.awt.Font;  
import java.awt.Graphics;  
import java.awt.image.BufferedImage;  
import java.io.IOException;  
import java.util.Random;  
  
import javax.imageio.ImageIO;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession; 

public class AuthImageServlet extends HttpServlet {
		private static final long serialVersionUID = 1L;
	    //设置字母的大小,大小     
	    private Font mFont = new Font("Times New Roman", Font.PLAIN, 22);     
	    public void init() throws ServletException     
	    {     
	        super.init();     
	    }     
	    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);     
	    }     
	    
	    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException     
	    {     
	        response.setHeader("Pragma","No-cache");     
	        response.setHeader("Cache-Control","no-cache");     
	        response.setDateHeader("Expires", 0);     
	        //表明生成的响应是图片     
	        response.setContentType("image/jpeg");     
	             
	        int width=80, height=35;/*设置画布宽度和高度*/     
	        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);     
	             
	        Graphics g = image.getGraphics();     
	        Random random = new Random();     
	        g.setColor(getRandColor(200,250));     
	        g.fillRect(1, 1, width-1, height-1);     
	        g.setColor(new Color(102,102,102));     
	        g.drawRect(0, 0, width-1, height-1);     
	        g.setFont(mFont);     
	    
	        g.setColor(getRandColor(160,200));     
	    
	        //画随机线     
	        for (int i=0;i<155;i++)     
	        {     
	            int x = random.nextInt(width - 1);     
	            int y = random.nextInt(height - 1);     
	            int xl = random.nextInt(6) + 1;     
	            int yl = random.nextInt(12) + 1;     
	            g.drawLine(x,y,x + xl,y + yl);     
	        }     
	    
	        //从另一方向画随机线     
	        for (int i = 0;i < 70;i++)     
	        {     
	            int x = random.nextInt(width - 1);     
	            int y = random.nextInt(height - 1);     
	            int xl = random.nextInt(12) + 1;     
	            int yl = random.nextInt(6) + 1;     
	            g.drawLine(x,y,x - xl,y - yl);     
	        }     
	    
	        //生成随机数,并将随机数字转换为字母     
	        String sRand="";
	        char ctmp = 0 ;
	        for (int i=0;i<4;i++)     
	        {     
	        	//ASCII码:65～90为26个大写英文字母,97～122号为26个小写英文字母,48～57为0到9十个阿拉伯数字
	            int itmp = 0;
	            int codeNum = random.nextInt(9);//产生随机数,决定产生数字还是字母
	            if(codeNum % 2 == 0){//绘画大写字母
	            	codeNum = random.nextInt(9);//产生随机数,决定产生大写字母还是小写字母
	            	if(codeNum % 2 == 0){//产生小写字母
	            		itmp = random.nextInt(26) + 97;
	            		ctmp = (char)itmp;
	            	}else{//产生大写字母
	            		itmp = random.nextInt(26) + 65;
	            		ctmp = (char)itmp;
	            	}
	            	sRand += String.valueOf(ctmp);//将产生的字母字符拼接成字符串,存放到session中 
	            }else{//产生数字
	            	ctmp = (char)(random.nextInt(10)+48);
	            	sRand += String.valueOf(ctmp);//将产生的数字拼接成字符串,存放到session中 
	            }
	            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
            	int intY = random.nextInt(8);//产生随机数控制纵坐标
 	            g.drawString(String.valueOf(ctmp),15*i+10,16+intY);//控制每个字符的绘画位置
	        }     
	    
	        HttpSession session = request.getSession(true);     
	        session.setAttribute("rand",sRand);/*将验证码放入session中进行验证*/     
	        g.dispose();     
	        ImageIO.write(image, "JPEG", response.getOutputStream());     
	    }   
}

 ③web.xml的修改

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  
  <servlet>
    <servlet-name>AuthImageServlet</servlet-name>
    <servlet-class>com.util.servlet.AuthImageServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>AuthImageServlet</servlet-name>
    <url-pattern>/servlet/AuthImageServlet</url-pattern>
  </servlet-mapping>
  
  <servlet>
    <servlet-name>CheckCodeIsRight</servlet-name>
    <servlet-class>com.util.servlet.CheckCodeIsRightServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CheckCodeIsRight</servlet-name>
    <url-pattern>/servlet/CheckCodeIsRight</url-pattern>
  </servlet-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 ④JSP页面的编写

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>验证码</title>
<script type="text/javascript" src="./comm/js/jquery.js"></script>
<script type="text/javascript">
	$(function() {
		$("#submit").click(function() {
			var code = $("#code").val();
			$.ajax({
				url : "servlet/CheckCodeIsRight",
				type : "POST",
				data : {"code" : code},
				dataType : "text",
				async : false,//同步执行  
				erro : function(data){alert("erro");},
				success : function(data) {
					if(data == "1"){
						alert("验证码输入正确");
					}else{
						alert("验证码输入有误!");
						changeCode();s
					}
				}
			});
		});
	})
	function changeCode() {
		var imgNode = document.getElementById("vimg");
		imgNode.src = "servlet/AuthImageServlet?t=" + Math.random(); // 防止浏览器缓存的问题       
	}
</script>
</head>
<body>
	<form action="checkServlet" method="post">
		<label>输入验证码</label><br /> <input type="text" name="randomCode"
			id="code" /> <img style="cursor: pointer;" id="vimg"
			title="看不清?点击换一个" onclick="changeCode();"
			src="servlet/AuthImageServlet"> <br /> <input type="button"
			value="submit" id="submit">
	</form>
</body>
</html>