老师，配置过滤器后白屏怎么办？

package com.zj.hospital.controller;

import com.zj.hospital.entity.Category;
import com.zj.hospital.entity.User;
import com.zj.hospital.service.CategoryService;
import com.zj.hospital.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.text.ParseException;
import java.util.List;

@Controller("DefaultController")
public class DefaultController {

   @Qualifier("categoryService")
   @Autowired
   private CategoryService categoryService;

   @Autowired
   private UserService userService;
   // index.do
   public void index(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, ParseException {
       List<Category> categories = categoryService.findAll();
       for (Category c : categories) {
           System.out.println(c.toString());
       }
       request.setAttribute("categories",categories);
       request.getRequestDispatcher("/index.jsp").forward(request, response);
   }

   // /toLogin.do
   public void toLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       System.out.println("ddddd================");
       request.getRequestDispatcher("login.jsp").forward(request,response);
   }

   // /login.do
   public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, ParseException {
       String username = request.getParameter("username");
       String password = request.getParameter("password");
       User user = userService.login(username, password);
       if (user == null) {
           request.setAttribute("msg","用户名或密码错误");
           request.getRequestDispatcher("../login.jsp").forward(request,response);
       } else {
           HttpSession session = request.getSession();
           session.setAttribute("user",user);
           request.getRequestDispatcher("/category/list.do").forward(request,response);
       }
   }
}

package com.zj.hospital.global;


import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class AuthFilter implements Filter {
   @Override
   public void init(FilterConfig filterConfig) throws ServletException {

   }

   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
       HttpServletRequest request = (HttpServletRequest) servletRequest;
       HttpServletResponse response = (HttpServletResponse) servletResponse;
       //String path = request.getRequestURI();
       String path = request.getServletPath();
       if (path.toLowerCase().indexOf("login")!=-1) {
           filterChain.doFilter(request,response);
       }else{
           HttpSession session = request.getSession();
           Object obj = session.getAttribute("user");
           if (obj!=null) {
               filterChain.doFilter(request,response);
           }else{
               response.sendRedirect(request.getContextPath()+"/toLogin.do");
           }
       }
   }

   @Override
   public void destroy() {

   }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
        version="3.1">

   <filter>
   <filter-name>encoding</filter-name>
   <filter-class>com.zj.hospital.global.EncodingFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>encoding</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

   <filter>
       <filter-name>Auth</filter-name>
       <filter-class>com.zj.hospital.global.AuthFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>Auth</filter-name>
       <url-pattern>*.jsp</url-pattern>
   </filter-mapping>
   <filter-mapping>
       <filter-name>Auth</filter-name>
       <url-pattern>*.do</url-pattern>
   </filter-mapping>

   <servlet>
       <servlet-name>Global</servlet-name>
       <servlet-class>com.zj.hospital.global.DispatchServlet</servlet-class>
   </servlet>
   <servlet-mapping>
       <servlet-name>Global</servlet-name>
       <url-pattern>*.do</url-pattern>
   </servlet-mapping>


</web-app>