實現一個如下的驗證碼的案例；
大致思路如下：
需要的jar包可以通過如下網址獲取：http://download.csdn.net/detail/panpan_1994/9621655
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>
<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">
function fun(){
var img= document.getElementById("one");
img.src="/demo-login/AServlet?date="+new Date();
}
</script>
</head>
<body>
<form action="/demo-login/BServlet">
用戶名:
<input type="text" name="name" />
<br>
密碼:
<input type="password" name="password" />
<br>
驗證碼:
<input type="text" name="code" size="4" />
<img id="one" src="/demo-login/AServlet">
<a href="javascript:void(0)" onclick="fun();">看不清，換一張</a>
<font color="red">${requestScope.error }</font>
<br>
<input type="submit" value="登錄" />
</form>
</body>
</html>AServlet.java
public class AServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("img/jpeg");
ValidateCode code = new ValidateCode(150, 70, 4, 20);
String str = code.getCode(); request.getSession().setAttribute("code", str);
System.out.println(str);
code.write(response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}BServlet.java
public class BServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String code = request.getParameter("code");
String sessCode = (String) request.getSession().getAttribute("code");
if (code.equalsIgnoreCase(sessCode)) {
response.sendRedirect("/demo-login/index.jsp");
} else {
request.setAttribute("error", "請重新輸入驗證碼！");
request.getRequestDispatcher("/login.jsp").forward(request,
response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
