Springboot2.3实现登录拦截

package com.xxxxx.config.intercepters;

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

import com.xxxxx.dto.User;
import com.xxxxx.vo.ResponseData;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import java.io.IOException;
import java.io.PrintWriter;

/**
 * @Author xxxx
 * @Date 2020/6/10 19:17
 * @Version 1.0
 * @Description 登录拦截器
 */
@Slf4j
@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        HttpSession session=request.getSession();
        User user = (User)session.getAttribute("User");
        if(user!=null){
            return true;
        }
        returnJson(response);
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                           ModelAndView modelAndView) throws Exception {
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {

    }
    private void returnJson(HttpServletResponse response){
        PrintWriter writer = null;
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/json; charset=utf-8");
        try {
            writer = response.getWriter();
            ResponseData responseData = new ResponseData();
            responseData.setCode(500);
            responseData.setMsg("您已登出，请重新登录！");
            writer.print(responseData);
        } catch (IOException e){
            log.error("拦截器输出流异常",e);
        } finally {
            if(writer != null){
                writer.close();
            }
        }
    }

}

package com.xxxxx.config;

import com.xxxxx.config.intercepters.LoginInterceptor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
/**
 * @Author xxxxx
 * @Date 2020/6/10 19:30
 * @Version 1.0
 * @Description 注册登录拦截器
 */
@Slf4j
@Configuration
public class InterceptorConfig implements WebMvcConfigurer{
    @Autowired
    private LoginInterceptor interceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(interceptor)
                .addPathPatterns("/**")
                .excludePathPatterns("/login/*");
        log.info("登录拦截器注册成功！");
    }
}

package com.xxxxx.vo;

import lombok.Data;

import java.io.Serializable;

/**
 * @Author xxxx
 * @Date 2020/6/5 10:41
 * @Version 1.0
 * @Description 返回前端数据
 */
@Data
public class ResponseData implements Serializable {
    private int code;

    private String msg;

    private Object results;
}

package com.xxxxx.dto;

import lombok.Data;

import java.io.Serializable;

/**
 * @Author xxxx
 * @Date 2020/6/11 11:55
 * @Version 1.0
 * @Description 用户实体类
 */
@Data
public class User implements Serializable {

    /**
     * 用户id
     */
    private Integer userId;
    /**
     * 用户账号
     */
    private String userName;

    private String sessionId;
}