java验证码（采用struts2实现）
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
<?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>