转自：http://hogwartsrow.iteye.com/blog/1558721
很多新手对图片验证码不是很了解，最近自己也与做这个功能，于是决定把自己的用个代码给大家分享一下，接下来我们就来看看一个实例吧。其中包括jsp实现的动态验证码，以每次请求都随即生成5个数字为例，用法就是在JSP页面中取出该验证码的值，用session保存的，进行判断比较就可以了。工程架构如图：
注意一点，其中commons-lang.jar就本项目需要加入，可能因为不同写法，此包可有可无，特此说明。同时页面使用了jquery，需要引入jquery-1.3.2.min.js文件。
首先，先写一个动态图片生成的Servlet类--AuthCode.java，当然也可以使用Struts来完成这个功能，代码如下：
package com.fz.cloudsync.web.config;
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 org.apache.commons.lang.RandomStringUtils;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class AuthCode extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
/**
* Constructor of the object.
*/
public AuthCode() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
int width = 75;
int height = 25;
// 取得一个5位随机字母数字字符串
String s = RandomStringUtils.random(5, true, true);
// 保存入session,用于与用户的输入进行比较.
// 注意比较完之后清除session.
HttpSession session = request.getSession(true);
session.setAttribute("authCode", s);
response.setContentType("images/jpeg");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
ServletOutputStream out = response.getOutputStream();
BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
// 设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
// 设定字体
Font mFont = new Font("华文新魏", Font.HANGING_BASELINE, 18);// 设置字体
g.setFont(mFont);
// 画边框
// g.setColor(Color.BLACK);
// g.drawRect(0, 0, width - 1, height - 1);
// 随机产生干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 200));
// 生成随机类
Random random = new Random();
for (int i = 0; i < 155; i++) {
int x2 = random.nextInt(width);
int y2 = random.nextInt(height);
int x3 = random.nextInt(12);
int y3 = random.nextInt(12);
g.drawLine(x2, y2, x2 + x3, y2 + y3);
}
// 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)));
// 第一位指随机数，第二位指随机数左右位移，第三位指随机数上下位移
g.drawString(s, 10, 18);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write((BufferedImage) image, "JPEG", out);
out.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// 给定范围获得随机颜色
private 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);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
其次，JSP页面--index.jsp代码如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript" src="<%=path %>/js/jquery-1.3.2.min.js"></script>
<script language="javascript" type="text/javascript">
function changeImg(){
$("#authCode").attr("src","<%=path %>/servlet/AuthCode?d="+new Date().valueOf());
}
</script>
</head>
<body>
<center>
<img src="<%=path %>/servlet/AuthCode" alt="验证码" id="authCode" onclick="changeImg()" />
<a href="#" onclick="changeImg()">看不清，换一张！</a>
</center>
</body>
</html>
再次，配置文件web.xml代码如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<servlet-name>AuthCode</servlet-name>
<servlet-class>com.fz.cloudsync.web.config.AuthCode</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AuthCode</servlet-name>
<url-pattern>/servlet/AuthCode</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
最后，只需要在tomcat下，部署本工程就可以了，效果如下：
结束语：希望这篇关于AuthCode的博文可以给初学者带来较大帮助，对于代码不足之处，还请多多谅解，给予指出！附源代码，下载地址：http://dl.iteye.com/topics/download/e476742c-79c4-315d-9675-314273a83741。
结束语：希望这篇关于AuthCode的博文可以给初学者带来较大帮助，对于代码不足之处，还请多多谅解，给予指出！附源代码，下载地址：http://dl.iteye.com/topics/download/e476742c-79c4-315d-9675-314273a83741。