ArgumentResolver

로그인 검증 예시

controller

@GetMapping("/")
 public String homeLoginV3ArgumentResolver(@Login Member loginMember, Model
 model) {
 //세션에 회원 데이터가 없으면 home if (loginMember == null) {
        return "home";
    }
//세션이 유지되면 로그인으로 이동 model.addAttribute("member", loginMember); return "loginHome";
}

어노테이션 생성

package hello.login.web.argumentresolver;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 @Target(ElementType.PARAMETER)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Login {
 }

@Target(ElementType.PARAMETER): 파라미터에만 사용
@Retention(RetentionPolicy.RUNTIME): 리플렉션 등을 활용할 수 있도록 런타임까지 애노테이션 정 보가 남아있음

ArgumentResolver

 package hello.login.web.argumentresolver;
 import hello.login.domain.member.Member;
 import hello.login.web.SessionConst;
 import lombok.extern.slf4j.Slf4j;
import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
@Slf4j
public class LoginMemberArgumentResolver implements
HandlerMethodArgumentResolver {
    @Override
    public boolean supportsParameter(MethodParameter parameter) {
log.info("supportsParameter 실행");
        boolean hasLoginAnnotation =
parameter.hasParameterAnnotation(Login.class);
        boolean hasMemberType =
Member.class.isAssignableFrom(parameter.getParameterType());
        return hasLoginAnnotation && hasMemberType;
    }
@Override
    public Object resolveArgument(MethodParameter parameter,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
WebDataBinderFactory binderFactory) throws Exception {
log.info("resolveArgument 실행");
        HttpServletRequest request = (HttpServletRequest)
webRequest.getNativeRequest();
        HttpSession session = request.getSession(false);
        if (session == null) {
            return null;
        }
        return session.getAttribute(SessionConst.LOGIN_MEMBER);
    }
 }

• supportsParameter(): @Login 애노테이션이 있으면서 Member 타입이면 해당 ArgumentResolver 가 사용된다.
• resolveArgument(): 컨트롤러 호출 직전에 호출 되어서 필요한 파라미터 정보를 생성해준다. 여기서는 세션 에 있는 로그인 회원 정보인 member 객체를 찾아서 반환해준다. 이후 스프링MVC는 컨트롤러의 메서드를 호출 하면서 여기에서 반환된 member 객체를 파라미터에 전달해준다.

config

package hello.login;
 import hello.login.web.argumentresolver.LoginMemberArgumentResolver;
 import hello.login.web.filter.LogFilter;
 import hello.login.web.filter.LoginCheckFilter;
 import hello.login.web.interceptor.LogInterceptor;
 import hello.login.web.interceptor.LoginCheckInterceptor;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 import javax.servlet.Filter;
 import java.util.List;
 @Configuration
 public class WebConfig implements WebMvcConfigurer {
@Override
     public void addArgumentResolvers(List<HandlerMethodArgumentResolver>
 resolvers) {
         resolvers.add(new LoginMemberArgumentResolver());
     }
//...
}

참고자료: 스프링 MVC 2편 - 백엔드 웹 개발 활용 기술(인프런 김영한)