java验证码（采用struts2实现)转

第一步：编写验证码的Action

 package com;

 import java.awt.Color;
 import java.awt.Font;
 import java.awt.Graphics;
 import java.awt.image.BufferedImage;
 import java.util.Random;

 import javax.imageio.ImageIO;
 import javax.servlet.ServletOutputStream;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 import org.apache.commons.lang.RandomStringUtils;
 import org.apache.struts2.ServletActionContext;
 public class AuthCodeAction {
     private HttpServletResponse response = ServletActionContext.getResponse();
     private HttpServletRequest request = ServletActionContext.getRequest();

     public String execute() {
         try {
             int width = 50;
             int height = 18;
             // 取得一个4位随机字母数字字符串
             String s = RandomStringUtils.random(4, 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("Times New Roman", Font.BOLD, 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)));

             g.drawString(s, 2, 16);

             // 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();
         }
         return null;
     }

     private Color getRandColor(int fc, int bc) { // 给定范围获得随机颜色
         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);
     }
 }

第二步：配置action

<span style="font-size:18px;"><?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
    <package name="test" namespace="/test" extends="struts-default">
        <action name="authCode" class="com.AuthCodeAction" method="execute">
        </action>
    </package>
</struts>

第三步：编写jsp页面（采用jquery实现动态刷新）

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%
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>验证码</title>
    <script type="text/javascript" src="js/jquery-1.6.2.min.js">
    </script>
    <script type="text/javascript">
    function changeImg(){
        $("#authCode").attr("src","test/authCode.action?d="+new Date().valueOf());
    }
    </script>
  </head>

  <body>
  <center>
           <br>
           <img src="test/authCode.action" alt="验证码" id="authCode" onclick="changeImg()">
          <a href="#" onclick="changeImg()">看不清，换一张！</a>
  </center>
  </body>
</html>