컨트롤러에 접근하기 직전 또는 후에 들어간다.

인터셉터로 접근하면 쓰로우를 날릴 수 있다.

로그인 인터셉터 만들기

package shop.mtcoding.blog._core.interceptor;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import shop.mtcoding.blog._core.errors.exception.Exception401;
import shop.mtcoding.blog.user.User;

public class LoginInterceptor implements HandlerInterceptor{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle............");
        HttpSession session = request.getSession();

        User sessionUser = (User) session.getAttribute("sessionUser");
        if(sessionUser == null){
            throw new Exception401("로그인 하셔야 해요");
        }
        return true;
    }
}

로그인 인터셉터 등록

package shop.mtcoding.blog._core.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import shop.mtcoding.blog._core.interceptor.LoginInterceptor;

@Configuration // IoC
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/board/**", "/user/**")
                .excludePathPatterns("/board/{id:\\\\d+}");

    }
}