SpringBoot 增加 拦截器 判断是否登录

1、创建拦截器

package com.example.demo.interceptor;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 〈一句话功能简述〉<br>
 * 〈拦截器〉
 *
 * @author 丶Zh1Guo
 * @create 2018/11/22
 * @since 1.0.0
 */
public class LoginInterceptor implements HandlerInterceptor {
    private Logger logger = LoggerFactory.getLogger(LoginInterceptor.class);

    // 在请求处理之前，只有返回true才会执行请求
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        logger.info("[拦截器]启动登录状态拦截");
        // 得到session
        HttpSession session = request.getSession();
        logger.info("[拦截器]sessionID:" + session.getId());
        // 得到用户信息
        Object userInfo = session.getAttribute("userInfo");
        //判断用户是否登录
        if (userInfo != null) {
            logger.info("[拦截器]用户已经登录,用户名，密码：" + session.getAttribute("userInfo"));
            return true;
        } else {
            //不存在跳转至登录页
            response.sendRedirect(request.getContextPath() + "/");    // 跳转到首页登录
            logger.info("[拦截器]用户没有登录,已跳转到:" + request.getContextPath() + "/");
            return false;
        }
    }

    // 视图渲染后执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    // 请求处理后，视图渲染前
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

2、.继承WebMvcConfigureAdapter类，覆盖其addInterceptors接口,注册自定义的拦截器

@Configuration 注解一定要有

package com.example.demo.interceptor;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * 〈一句话功能简述〉<br>
 * 〈自定义配置类〉
 *
 * @author 丶Zh1Guo
 * @create 2018/11/22
 * @since 1.0.0
 */
@Configuration
public class LoginConfig implements WebMvcConfigurer {

    /**
     * 该方法用于注册拦截器
     * 可注册多个拦截器，多个拦截器组成一个拦截器链
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // addPathPatterns 添加路径
        // excludePathPatterns 排除路径
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/sys/*"); // 拦截sys路径下的url
//              .excludePathPatterns("");
    }
}

3、LoginController

/**
 * Copyright (C), 2017-2018, XXX有限公司
 * FileName: LoginController
 * Author:   丶Zh1Guo
 * Date:     2018/11/22 11:10
 * Description: 登录
 * History:
 * <author>          <time>          <version>          <desc>
 * 作者姓名           修改时间           版本号              描述
 */
package com.example.demo.controller;

import com.example.demo.dao.UserDAO;
import com.example.demo.pojo.User;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;

/**
 * 〈一句话功能简述〉<br>
 * 〈登录〉
 *
 * @author 丶Zh1Guo
 * @create 2018/11/22
 * @since 1.0.0
 */
@Controller
public class LoginController {
    // 日志
    private Logger logger = LoggerFactory.getLogger(LoginController.class);

    @Autowired
    private UserDAO userDAO;


    // 启动服务自动跳转登录
//    @RequestMapping(value = {"/", "/login"})
    @RequestMapping(value = "/")
    public String login() {
        return "login";
    }

    // 登录
    @RequestMapping(value = "/loginCheck", method = RequestMethod.POST)
    @ResponseBody
    public String loginCheck(HttpServletRequest request) {
        // 获取登录信息
        String userName = request.getParameter("userName");
        String password = request.getParameter("password");

        // 封装成对象
        User user = new User();
        user.setUserName(userName);
        user.setPassword(password);

        // 校验用户信息
        User info = userDAO.checkUser(user);
        if (info != null) {
            request.getSession().setAttribute("userInfo", userName + "-" + password);
            logger.info("登录成功，用户名：" + userName + "密码：" + password);
            return "success";
        } else {
            logger.info("登录失败，用户名：" + userName + "密码：" + password);
            return "fail";
        }
    }
}

4、未登录会自动跳转到登录页面