login 拦截器

    <filter>
        <filter-name>loginFilter</filter-name>
        <filter-class>runtong.util.LoginFilter</filter-class>
    </filter>
   <filter-mapping>
        <filter-name>loginFilter</filter-name>
        <url-pattern>*.action</url-pattern>
        <url-pattern>*.jsp</url-pattern>
    </filter-mapping>

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.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import runtong.entity.Users;

public class LoginFilter implements Filter{

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        
        HttpServletRequest httpRequest=(HttpServletRequest)request;
        HttpServletResponse httpResponse=(HttpServletResponse)response;
        HttpSession session=httpRequest.getSession();
        Users user=(Users)session.getAttribute("user");
        String uri=httpRequest.getRequestURI();
        String a[]=uri.split("/");
        if(user!=null||a[a.length-1].equals("login.jsp")){
            chain.doFilter(request,response);
        }
        else{
            String contextPath=httpRequest.getContextPath();
            httpResponse.sendRedirect(contextPath+"/login.jsp");
        }
        
        
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        
    }
}

$(document).ready(function() {
    if($("#LoginUser").val()=="null")
        window.top.location.href=$("#basePath").val()+"page/login.jsp";
});

<input type="hidden" value="<%=session.getAttribute("username")%>" id="LoginUser" />

session.put("username", list.get(0).getUserName());