ArgumentResolver 활용

@Login 애노테이션이 있으면 직접 만든 'ArgumentResolver가 동작해서 자동으로 세션에 있는 로그인 회원을 찾아주고, 없으면 null을 반환

@Login 애노테이션 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 런타임 까지 애노테이션 정보가 남아있다.

ArgumentResolver 직접 만들기

package hello.login.web.argumentResolver;

import hello.login.domain.member.Member;
import hello.login.web.session.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 hasMemberType && hasLoginAnnotation;
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest webRequest, WebDataBinderFactory webDataBinderFactory) throws Exception {
        log.info("resolverArgument 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 Member타입이면 해당 ArgumentResolver가 사용된다.
• resolveArgument() : 컨트롤러 호출 직전에 호출 되어서 필요한 파라미터 정보를 생성해준다.

WebMvcConfigurer 설정 추가

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
        resolvers.add(new LoginMemberArgumentResolver());
    }
    .
    .
    .
 }

• addArgumentResolvers()를 오버라이딩 하여 등록하면 된다.