文件清单
ImageServlet.java
web.xml
image.jsp
result.jspImageServlet.java
package com.freud.test;
import java.awt.Color;
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;
/**
* 图片获取和验证Servlet
*
* @author Freud
* @version 1.0.0 - Date : 2015-05-11
*
*/
public class ImageServlet extends HttpServlet {
private static final long serialVersionUID = -5424418247489994690L;
private static final int WIDTH = 68;
private static final int HEIGHT = 22;
/**
* GET方式获取随机码图片
*/
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
BufferedImage bi = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
Graphics g = bi.createGraphics();
Color color = new Color(200, 150, 255);
g.setColor(color);
g.fillRect(0, 0, WIDTH, HEIGHT);
char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
Random r = new Random();
int len = ch.length, index;
/** 设置4位随机验证码 */
StringBuffer sb = new StringBuffer();
for (int i = 0; i < 4; i++) {
index = r.nextInt(len);
sb.append(ch[index]);
g.setColor(new Color(r.nextInt(88), r.nextInt(255), r.nextInt(255)));
g.drawString(ch[index] + "", (i * 15) + 3, 18);
}
System.out.println("获取图形验证码【" + sb.toString() + "】");
request.getSession().setAttribute("randomStr", sb.toString());
// 设置响应类型,输出图片客户端不缓存
response.setDateHeader("Expires", 1L);
response.setHeader("Cache-Control", "no-cache, no-store, max-age=0");
response.addHeader("Pragma", "no-cache");
response.setContentType("image/jpeg");
ImageIO.write(bi, "jpg", response.getOutputStream());
}
/**
* POST方式验证随机码
*/
@Override
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String randomCode = request.getParameter("randomCode");
String existCode = (String) request.getSession().getAttribute(
"randomStr");
String ret = "您输入的[" + randomCode + "]和图片显示的[" + existCode + "]";
if (randomCode.equals(existCode)) {
System.out.println("通过验证 - " + ret);
request.setAttribute("result", "通过验证 - " + ret);
} else {
System.out.println("未通过验证 - " + ret);
request.setAttribute("result", "未通过验证 - " + ret);
}
request.getRequestDispatcher("/result.jsp").forward(request, response);
}
}web.xml
<?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>image</servlet-name>
<servlet-class>com.freud.test.ImageServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>image</servlet-name>
<url-pattern>/servlet/image</url-pattern>
</servlet-mapping>
</web-app>image.jsp
<%@ 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>随机验证码测试</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/image" method="post">
<label>请输入验证码</label>
<input type="text" name="randomCode">
<img id="randomImage" alt="随机验证码" src="${pageContext.request.contextPath}/servlet/image">
<a href="javascript:refreshImageCode()">刷新</a>
<input type="submit" value="验证">
</form>
<script type="text/javascript">
function refreshImageCode(){
/*
* 重新获取验证码，并使用动态地址规避浏览器对同一路径下GET请求的图片缓存功能
*/
document.getElementById("randomImage").src = "${pageContext.request.contextPath}/servlet/image?_="+new Date();
}
</script>
</body>
</html>result.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>验证结果</title>
</head>
<body>
<label>${result }</label>
<a href="${pageContext.request.contextPath}/image.jsp">back</a>
</body>
</html>测试
在地址栏中输入http://localhost:8080/TestRandomImage/image.jsp，效果如下
!输入验证码FGJR之后，通过验证如下：
输入错误验证码之后，验证失败如下：
其他框架
- jcaptcha
- kaptcha