在SpringBoot项目中整合拦截器的详细步骤

package com.xing.springbootinterceptor.interceptor;

import com.xing.springbootinterceptor.model.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//自定义的拦截器 只有继承了HandlerInterceptor 自定义的类才算是一个拦截器
public class UserInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //编写拦截的规则
        //判断用户是否登录 从session中取值
        User user=(User) request.getSession().getAttribute("user");
        if(user==null){
            //未登录
            response.sendRedirect(request.getContextPath()+"/user/error");//重定向
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

package com.xing.springbootinterceptor.config;
import com.xing.springbootinterceptor.interceptor.UserInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

//表明这是一个配置类 即相当于之前的xml配置文件
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    //这个配置类主要用来添加拦截请求
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        String[] addPathPatterns={
                "/user/**"
        };//设置拦截的路径 不设置将会拦截所有的请求
        String[] excludePathPatterns={
                "/user/out",
                "/user/error",
                "/user/login"
        };//要排除的路径 排除的路径说明不需要用户登录也可以访问
        //InterceptorRegistry 拦截器注册类
        registry.addInterceptor(new UserInterceptor()).addPathPatterns(addPathPatterns).excludePathPatterns(excludePathPatterns);
//        WebMvcConfigurer.super.addInterceptors(registry);
    }
}

package com.xing.springbootinterceptor.controller;
import com.xing.springbootinterceptor.model.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
@RestController //该注解相当于@Controller+@ResponseBody
@RequestMapping("/user")
public class UserController {
    @RequestMapping("/login")
    public String login(HttpServletRequest request){
    //这里只是模拟登录 一旦输入该请求 则表示登录成功 便我往session中存值
        User user = new User();
        user.setId(1001);
        user.setUsername("张三");
        //将用户的信息存放到session中
        request.getSession().setAttribute("user",user);
        return "login success";
    }
    //该请求需要用户登录之后才可访问
    @RequestMapping("/center")
    public String center(){
        return "See Center Message";
    }
    //该请求不登录也可以访问
    @RequestMapping("/out")
    public String out(){
        return "Out See anytime";
    }
    //如果用户未登录访问了需要登录的请求 便会自动跳转到该路径
    @RequestMapping("/error")
    public String error(){
        return "error";
    }
}