1. AOP가 필요한 상황

• 모든 메소드의 호출 시간을 측정하고 싶을 때
• 공통 관심 사항 VS 핵심 관심 사항
• 회원 가입 시간, 회원 조회 시간을 측정하고 싶을 때

💡

/service/MemberService

package hello.hellospring.service;
import hello.hellospring.domain.Member;
import hello.hellospring.repository.MemberRepository;
import hello.hellospring.repository.MemoryMemberRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;
import java.util.Optional;

@Transactional // rollback
public class MemberService {
    private final MemberRepository memberRepository;

    public MemberService(MemberRepository memberRepository) {
        this.memberRepository = memberRepository;
    }

    // 회원가입
    public Long join(Member member) {
        long start = System.currentTimeMillis(); // 기능 시작 전 시간 측정
        try {
            validateDuplicateMember(member); //중복 회원 검증
            memberRepository.save(member);
            return member.getId();
        } finally {
            long finish = System.currentTimeMillis(); // 기능 끝난 후 시간 측정
            long timeMs = finish - start; // 기능하는 동안 걸린 시간
            System.out.println("join " + timeMs + "ms");
        }
    }

    private void validateDuplicateMember(Member member) {
        memberRepository.findByName(member.getName()) // 이미 있는 회원의 이름이 들어오면
                .ifPresent(m -> {
                    throw new IllegalStateException("이미 존재하는 회원입니다.");
                });
    }

    // 전체 회원 조회
    public List<Member> findMembers() {
        long start = System.currentTimeMillis();
        try {
            return memberRepository.findAll();
        } finally {
            long finish = System.currentTimeMillis();
            long timeMs = finish - start;
            System.out.println("findMembers " + timeMs + "ms");
        }
    }

    public Optional<Member> findOne(Long memberId) {
        return memberRepository.findById(memberId);
    }
}

2. AOP 적용

💡 AOP : Aspect Oriented Programming

→ 공통 관심 사항과 핵심 관심 상황을 분리하는 것~~.ᐟ.ᐟ

/aop/TimeTraceAop

package hello.hellospring.aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class TimeTraceAop {

   @Around("execution(* hello.hellospring..*(..))") // hello.hellospring 밑에 있는 모든 것들에게 적용한다
   public Object execute(ProceedingJoinPoint joinPoint) throws Throwable {

       long start = System.currentTimeMillis();
       System.out.println("START: " + joinPoint.toString());

       try {
           return joinPoint.proceed();
       } finally {
           long finish = System.currentTimeMillis();
           long timeMs = finish - start;
           System.out.println("END: " + joinPoint.toString() + " " + timeMs + "ms");
       }
   }
}