使用Ajax开展验证码的刷新
日期：2014-05-16 浏览次数：20986 次
使用Ajax进行验证码的刷新
废话不多说，大部分网站都有设置验证码防止恶意攻击。现在用最简单的实现进行我们的验证码刷新。
注册页面：login.jsp
<%@ 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>
<script src="../js/check_login.js" type="text/javascript"></script><!--这里的路径要这样设置 -->
<base href="<%=basePath%>">
<title>欢迎登陆</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">
<!-- 这里会需要引入外部的CSS文件，路径如下 -->
<link rel="stylesheet" type="text/css" href="CSS/style.css">
</head>
<style type="text/css">
</style>
<body>
<div id="main">
<form method="post" action="user/checkUserLogin.jsp">
<table align="left">
<tr>
<td>用户名：</td>
<td><input type="text" name="username" id="username" onchange="return check_username() == true;"></td>
<td></td>
<td><div id="display_username" class="display"></div></td>
</tr>
<tr>
<td>密 码:</td>
<td><input type="password" name="password" id="password" onchange="return check_password() == true"></td>
<td></td>
<td><div id="display_password" class="display"></div></td>
</tr>
<tr>
<td>验证码：</td>
<td><input type="text" name="certCode" maxlength="4" id="certCode" onchange="return check_certCode()==true;"></td>
<td><img src="makeCertPic.jsp" id="img" title="refresh" name="img">
<a href="JavaScript:reLoadImg();">换一张</a></td>
<td><div id="display_certCode" class="display"></div></td>
</tr>
<tr><td></td><td></td>
<td><font size="4"><input type="submit" value="登陆"></font></td></tr>
</table>
</form>
</div>
</body>
</html>
生成验证码图片：makeCertPic.jsp
<%@page contentType="image/jpeg" %>
<jsp:useBean id="image" scope="page" class="util.makeCertPic" />
<%
String str = image.getCertPic(0,0,response.getOutputStream());
session.setAttribute("certCode", str);
out.clear();//该行及下一行代码可以解决respons.getOutputStream() has already been called 的问题
out = pageContext.pushBody();
%>
生成验证码的类：makeCertPic.java
package util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
im
利用Ajax实现验证码的刷新
废话不多说，大部分网站都有设置验证码防止恶意攻击。现在用最简单的实现进行我们的验证码刷新。
注册页面：login.jsp
<%@ 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>
<script src="../js/check_login.js" type="text/javascript"></script><!--这里的路径要这样设置 -->
<base href="<%=basePath%>">
<title>欢迎登陆</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">
<!-- 这里会需要引入外部的CSS文件，路径如下 -->
<link rel="stylesheet" type="text/css" href="CSS/style.css">
</head>
<style type="text/css">
</style>
<body>
<div id="main">
<form method="post" action="user/checkUserLogin.jsp">
<table align="left">
<tr>
<td>用户名：</td>
<td><input type="text" name="username" id="username" onchange="return check_username() == true;"></td>
<td></td>
<td><div id="display_username" class="display"></div></td>
</tr>
<tr>
<td>密 码:</td>
<td><input type="password" name="password" id="password" onchange="return check_password() == true"></td>
<td></td>
<td><div id="display_password" class="display"></div></td>
</tr>
<tr>
<td>验证码：</td>
<td><input type="text" name="certCode" maxlength="4" id="certCode" onchange="return check_certCode()==true;"></td>
<td><img src="makeCertPic.jsp" id="img" title="refresh" name="img">
<a href="JavaScript:reLoadImg();">换一张</a></td>
<td><div id="display_certCode" class="display"></div></td>
</tr>
<tr><td></td><td></td>
<td><font size="4"><input type="submit" value="登陆"></font></td></tr>
</table>
</form>
</div>
</body>
</html>
生成验证码图片：makeCertPic.jsp
<%@page contentType="image/jpeg" %>
<jsp:useBean id="image" scope="page" class="util.makeCertPic" />
<%
String str = image.getCertPic(0,0,response.getOutputStream());
session.setAttribute("certCode", str);
out.clear();//该行及下一行代码可以解决respons.getOutputStream() has already been called 的问题
out = pageContext.pushBody();
%>
生成验证码的类：makeCertPic.java
package util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
im
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