サーブレット＋jspでログインできないようにフィルタを実装する

package com.test.filter;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.Filter;
FilterChain; import javax.servlet;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http;
 
 
public class LoginFilter implements Filter {
  public static final String login_page = "/test/admin/index.jsp";
 public static final String logout_page = "/test/admin/Public/login.jsp";
 public void destroy(){
 
 }
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws ServletException, IOException {
 HttpServletRequest request = (HttpServletRequest)servletRequest;
 HttpServletResponse response = (HttpServletResponse)servletResponse;
 String currentURL = request.getRequestURI();
 String ctxPath = request.getContextPath();
 // access the current path of the page when the item name is removed
 String targetURL = currentURL.substring(ctxPath.length());
 HttpSession session = request.getSession(false);
 //judge the current page, if the current page is not the login page
 if(! ("/admin/Public/login.jsp".equals(targetURL))){
 System.out.println("1"+targetURL+"ctxPath:"+ctxPath+"currentURL:"+currentURL);
 // in not for the landing page, then judge, if not the landing page also no session then jump to the login page
 if(session == null || session.getAttribute("admin") == null){
 response.sendRedirect(logout_page);
 return;
 }else{
 // This means it is correct and will go to the next chain, if it does not exist, then do the normal page jump
 filterChain.doFilter(request, response);
 return;
 }
 }else{
 // This means if the current page is a landing page, jump to the landing page
 filterChain.doFilter(request, response);
 return;
 }
 
 }
 public void init(FilterConfig filterConfig)throws ServletException{
 
 }
 
}

<filter>
 <filter-name>LoginFilter</filter-name>
 <filter-class>com.test.filter.LoginFilter</filter-class>
 </filter>
 <filter-mapping>
 <filter-name>LoginFilter</filter-name>
 // This means that it is valid for all files with jsp suffix, but not for others
 <url-pattern>*.jsp</url-pattern>
</filter-mapping>