1_Annotion.java

@Documented
@Retention(RetentionPolicy.CLASS) // default CLASS -> SOURCE, RUNTIME으로 변경할 필요 없음
@Target(ElementType.METHOD)
public @interface PerformaceLogging {
}

2_Aspect.java

@Component
@Aspect
public class PerformanceAspect {
  
  @Around("@annotation(PerformaceLogging)") // bean으로 설정하는 방법도 있다.
  public Object logPeformace(ProceedingJoinPoint pjp) throws Throwable {
    long begin = System.currentTimeMills();
    Object returnProceed = pjp.proceed();
    System.out.println((System.currentTimeMillis() - begin));
    return returnProceed;
  }
}

3_use.java

@Service
public class TestService {

    @PerformaceLogging // 필요한 method에 annotation을 달아준다.
    public String test2() {
        try {
            Thread.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "test";
    }
}