Struts2使用过滤器验证登陆状态

1 <filter>     
2         <filter-name>loginFilter</filter-name>     
3         <filter-class>com.filter.LoginFilter</filter-class>     
4    </filter>     
5      <filter-mapping>  
6         <filter-name>loginFilter</filter-name>  
7         <url-pattern>/*</url-pattern>  
8  </filter-mapping>

1 HttpServletRequest request = ServletActionContext.getRequest();
2 request.getSession().setAttribute("username", username);

 1 package com.filter;
 2 
 3 import java.io.IOException;
 4 import javax.servlet.Filter;
 5 import javax.servlet.FilterChain;
 6 import javax.servlet.FilterConfig;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.ServletRequest;
 9 import javax.servlet.ServletResponse;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13 import javax.servlet.http.HttpSession;
14 
15 public class LoginFilter extends HttpServlet implements Filter {
16     public void destroy() {
17     }
18 
19     public void doFilter(ServletRequest sRequest, ServletResponse sResponse,      
20             FilterChain filterChain) throws IOException, ServletException{
21         
22         HttpServletRequest request = (HttpServletRequest) sRequest;      
23         HttpServletResponse response = (HttpServletResponse) sResponse;      
24         HttpSession session = request.getSession();      
25         String url=request.getServletPath();  
26         String contextPath=request.getContextPath();  
27         if(url.equals("")) url+="/";  
28         if((url.startsWith("/")&&!url.startsWith("/login"))){//若访问后台资源 过滤到login  
29              String user=(String)session.getAttribute("username");  
30              if(user==null){//转入管理员登陆页面  
31                   response.sendRedirect(contextPath+"/login.jsp"); 
32                   return;  
33              }  
34         }  
35           filterChain.doFilter(sRequest, sResponse);    
36     }  
37 
38     public void init(FilterConfig arg0) throws ServletException {
39 
40     }
41 }