Java web项目中的强制登录功能实现代码

为了避免直接进入项目中存在的页面，使用filter过滤器

新建一个类loginFilter:

package com.tjcu.filter;

import com.tjcu.entity.User;

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

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

}

@Override
   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
       HttpServletRequest request = (HttpServletRequest) servletRequest;
       HttpSession session = request.getSession();
       User user = (User) session.getAttribute("user");
       HttpServletResponse response = (HttpServletResponse) servletResponse;
       if (user!=null) {
           filterChain.doFilter(request,response);
       }else {
           response.sendRedirect(request.getContextPath()+"/login.jsp");
       }
   }

@Override
   public void destroy() {

}
}

在web文件中通知服务器开发了这个过滤器

web.xml:

 <filter>
   <filter-name>loginFilter</filter-name>
   <filter-class>com.tjcu.filter.loginFilter</filter-class>
 </filter>
 <filter-mapping>
   <filter-name>loginFilter</filter-name>
   <url-pattern>/main/*</url-pattern>
 </filter-mapping>

来源：https://blog.csdn.net/qq_51218906/article/details/121330375