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

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("loginSession");  
        if(loginuser == null){
            res.sendRedirect(indexPath);  
            return;  
        }
        chain.doFilter(request, response);  
    }  
  
    @Override  
    public void init(FilterConfig arg0) throws ServletException {  
        // TODO Auto-generated method stub   
    }  
  
}  

	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("loginSession", login);
		return "success";
	}

   <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>

    <script language="javascript">   
        if (top != window)   
      	    top.location.href = window.location.href;   
    </script>