拦截JSP页面，校验是否已登录 （struts2拦截action）

最近使用struts2做项目，需要拦截JSP以校验是否已经登，但struts2的过滤器链只能过滤action。后来发现在web.xml里可以直接增加javax.servlet.Filter实现类的过滤器，可以过滤JSP。请看代码
Filter实现类
[java] 
<span style="font-size:18px;">package com.common; 
 
import java.io.IOException; 
import javax.servlet.Filter; 
import javax.servlet.FilterChain; 
import javax.servlet.FilterConfig; 
import javax.servlet.ServletException; 
import javax.servlet.ServletRequest; 
import javax.servlet.ServletResponse; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
public class LoginFilter extends HttpServlet implements Filter {   
       
    private static final long serialVersionUID = 1L;   
   
    @Override   
    public void doFilter(ServletRequest request, ServletResponse response,   
            FilterChain chain) throws IOException, ServletException {   
        HttpServletRequest req = (HttpServletRequest)request;   
        HttpServletResponse res = (HttpServletResponse)response;   
        String path = req.getContextPath(); 
        String indexPath = req.getScheme()+"://"+req.getServerName()+":"+req.getServerPort()+path+ "/pages/login.jsp"; 
        if(req.getRequestURI().endsWith("login.jsp")) 
        { 
            chain.doFilter(request, response);  
            return; 
        } 
         
        Object loginuser = req.getSession().getAttribute("<strong><span style="color:#ff0000;">loginSession</span></strong>");   
        if(loginuser == null){ 
            res.sendRedirect(indexPath);   
            return;   
        } 
        chain.doFilter(request, response);   
    }   
   
    @Override   
    public void init(FilterConfig arg0) throws ServletException {   
        // TODO Auto-generated method stub    
    }   
   
}   
</span> 
登录方法：
[java]
<span style="font-size:18px;">  public String login() 
    { 
        Login login = new Login(); 
             
        //.......校验登录信息 
        ActionContext ctx = ActionContext.getContext(); 
        Map<String, Object> session = ctx.getSession(); 
        session.put("<strong><span style="color:#ff0000;">loginSession</span></strong>", login); 
        return "success"; 
    }</span> 
web.xml配置
[html] 
<filter>   
     <filter-name>setlog</filter-name>   
     <filter-class>com.common.LoginFilter</filter-class>   
</filter>   
<filter-mapping>   
     <filter-name>setlog</filter-name>   
     <url-pattern>/pages/home.jsp</url-pattern> 
     <url-pattern>/pages/channel/*</url-pattern> 
     <url-pattern>/pages/content/*</url-pattern> 
     <url-pattern>/pages/product/*</url-pattern> 
     <url-pattern>/pages/vodtask/*</url-pattern> 
</filter-mapping> 

注意，如果页面上使用了框架，则可能导致session超时后退出到登录页面，此时登录页面显示在框架的某个子页面，解决方法，在登录页面加入如下代码即可。
[html] 
<span style="font-size: 18px;">    <script language="javascript">    
        if (top != window)    
            top.location.href = window.location.href;    
    </script></span>