实现原理，在登录成功时在session中添加数据，中书写专门的拦截类判断是否有数据，来判断是否拦截，再在web.xml,中对拦截器进行配置

拦截类SysInterceptor：package com.zkz.interceptor;

import com.zkz.pojo.MallUser;

import javax.servlet.*;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.io.IOException;

public class SysInterceptor implements Filter {

@Override

public void init(FilterConfig filterConfig) throws ServletException {

}

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

// 对全栈url进行过滤

//将request和response对象强转为http类型

HttpServletRequest req=(HttpServletRequest)request;

HttpServletResponse resp = (HttpServletResponse)response;

//获取访问的地址

String url = req.getRequestURI();

//获取session中的对象判断是否登录

//拦截所有需要的url

//判断session中是有USER值，有则是登录过的

if(url.contains("/")) {

//获取session

HttpSession session = req.getSession();

MallUser user=(MallUser) session.getAttribute("USER");

if(user==null){

resp.sendRedirect("/admain/notlogin.html");

return;

}

}

//继续执行过滤连的剩余部分

chain.doFilter(req, resp);

}

@Override

public void destroy() {

}

}

然后在web.xml中配置拦截器：

UrlFilter

com.zkz.interceptor.SysInterceptor

UrlFilter

/admain/pages/*

登录(responseJsonResult是返回的一个类不用详解)：@RequestMapping("/login")

@ResponseBody

public ResponseJsonResult page(@NotNull HttpServletRequest request, HttpSession session) throws IOException {

ResponseJsonResult responseJsonResult = new ResponseJsonResult();

String username = request.getParameter("username");

String password = request.getParameter("password");

boolean status = userService.longin(username, password);

MallUser mallUser = new MallUser();

if (status !=true){

session.setAttribute("USER", mallUser);

return responseJsonResult;

}

responseJsonResult.setStatus(200);

return responseJsonResult;

}