Filter登录验证过滤器（全局）

时间：2015-08-26 17:22:35 阅读：204 评论：0 收藏：0 [点我收藏+]

标签：

通过Filter来定义一个登录验证过滤器，这是就不需要在每一个JSP页面添加判断用户合法性的代码了。

以下示例中包含了5个文件，一个是登录表单LoginForm.jsp，一个是登录判断页LoginConf.jsp，

一个是登录验证过滤器LoginFilter.java，一个是登录成功页面LoginSucess.jsp，一个是登录失败

页面Loginfailure.jsp。

LoginForm.jsp

 1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
 2 
 3 <html>
 4   <head><title>用户登录</title></head>
 5   
 6   <body>
 7 <center>
 8 <form action="LoginConf.jsp" method="post">
 9 <table>
10 <tr>
11 <td colspan="2">用户登录</td>
12 </tr>
13 <tr>
14 <td>用户名：</td>
15 <td><input type="text" name="username"></td>
16 </tr>
17 <tr>
18 <td>密&nbsp;&nbsp;码</td>
19 <td><input type="password" name="userpassword"></td>
20 </tr>
21 <tr>
22 <td colspan="2">
23 <input type="submit" value="登录">
24 <input type="reset" value="重置">
25 </td>
26 </tr>
27 </table>
28 </form>
29 </center>
30   </body>
31 </html>

LoginConf.jsp

 1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
 2 
 3 <html>
 4   <head><title>登录判断</title></head>
 5   
 6   <body>
 7 <center>
 8 <% 
 9 //接受用户名，密码参数
10 String username=request.getParameter("username");
11 String userpassword = request.getParameter("userpassword");
12 
13 //判断用户名以及密码，如果为指定用户则跳转到登陆成功页面。
14 if("CeShi".equals(username)&&"123456".equals(userpassword)){
15 session.setAttribute("username",username);
16 %>
17 <jsp:forward page="LoginSuccess.jsp"/>
18 <%    
19 }
20 //如果不是指定用户，则跳转到登录失败页面
21 else{
22 %>
23 <jsp:forward page="LoginFailure.jsp" />
24 <%    
25 }
26 %>
27 </center>
28   </body>
29 </html>

LoginFilter.java

 1 package com.mhb;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.Filter;
 6 import javax.servlet.FilterChain;
 7 import javax.servlet.FilterConfig;
 8 import javax.servlet.ServletException;
 9 import javax.servlet.ServletRequest;
10 import javax.servlet.ServletResponse;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpSession;
13 
14 public class LoginFilter implements Filter {
15 
16 //初始化方法
17 public void init(FilterConfig arg0) throws ServletException {
18 System.out.println("登录验证过滤器初始化！");
19 }
20 
21 //过滤方法
22 public void doFilter(ServletRequest req, ServletResponse res,
23 FilterChain chain) throws IOException, ServletException {
24 HttpServletRequest request = (HttpServletRequest)req;
25 //获得session对象
26 HttpSession session = request.getSession();
27 String login = (String) session.getAttribute("username");
28 
29 //如果是登录判断页面，不用进行过滤检查
30 if("/JavaWeb/LoginConf.jsp".equals(request.getRequestURI())){
31 chain.doFilter(req, res);    
32 }else{
33 //判断用户是否进行登录，如果进行了登录则继续操作，否则跳转到登录页面
34 if(login == null || "".equals(login)){
35 request.getRequestDispatcher("LoginForm.jsp").forward(req, res);
36 }else{
37 chain.doFilter(req, res);
38 }
39 }
40 }
41 
42 //销毁方法
43 public void destroy() {
44 System.out.println("登录验证过滤器销毁！");
45 }
46 }

LoginSuccess.jsp

 1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
 2 
 3 <html>
 4   <head><title>登录成功</title></head>
 5   
 6   <body>
 7       <center>
 8 <h1>登录成功</h1>
 9 ${sessionScope.username}欢迎您的登录！
10 </center>
11   </body>
12 </html>

LoginFailure.jsp

1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
2 
3 <html>
4   <head><title>登录失败</title></head>
5   
6   <body>
7     <h1>登录失败</h1>
8   </body>
9 </html>

web.xml配置

 1   <filter>
 2       <filter-name>LoginFilter</filter-name>
 3       <filter-class>com.mhb.LoginFilter</filter-class>
 4   </filter>
 5   <filter-mapping>
 6       <filter-name>LoginFilter</filter-name>
 7       <url-pattern>/*</url-pattern>
 8   </filter-mapping>
 9 
10   <welcome-file-list>
11     <welcome-file>index.jsp</welcome-file>
12   </welcome-file-list>
13 </web-app>