public class LoginFilter implements Filter{

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

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        // TODO Auto-generated method stub
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        HttpSession session = req.getSession();
        StringBuffer url = req.getRequestURL();
        String login = (String) session.getAttribute("login");
    
        if (login!=null) {
                     //如果已经等了通过
            chain.doFilter(request, response);
        }else if (url.indexOf("login.do")>0||url.indexOf("login.jsp")>0) {
                          //可以访问jsp，也可以访问login。do对应的servlet，通过
            chain.doFilter(request, response);
        }
        
        else {
            
            resp.sendRedirect("/3G/login/login.jsp");
        }
        
    }

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

    

}

------解决方案--------------------
Java code

package group3.tsims.tools;

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;

public class AdminAuthorityFilter implements Filter {
    /*
     * (non-Javadoc)
     * @see javax.servlet.Filter#destroy()
     */
        public void destroy() {
            

        }
    /*
     * (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
        public void doFilter(ServletRequest request, ServletResponse response,
                FilterChain chain) throws IOException, ServletException {
            HttpServletRequest r