Spring : AOP with Java Config - @Around

0. 이 포스트는 Spring : AOP with Java Config 시리즈의 연속이다.

 

1. @Around는 @Before와 @After를 같이 사용하는 것과 같다. 하지만 좀 더 섬세한 컨트롤이 가능하다.

  1-1 @Around advice는 Proceeding Join Point를 받을 수 있다.

  1-2 Proceeding Join Point는 타겟 메소드의 직접 호출 할 수 있다.

 

2. Use cases

  2-1 로깅, 보안, 감사 등에 사용

  2-2 데이터의 전처리, 후처리 

  2-3 성능 측정

  2-4 예외 처리

 

3. 메소드의 실행시간을 측정하는 @Around advice 예제

  3-1 설정 클래스는 @Configuration, @EnableAspectJAutoProxy, @ComponentScan이 설정되어야 한다.

  3-2 @Around advice는 첫번 째인자로 ProceedingJoinPoint를 받고 있다.

    3-2-1 이 ProceedingJoinPoint의 proceed는 @Around의 타겟 메소드를 실행하고 그 메소드의 리턴 값을 반환한다.

  3-3 @Around는 advice는 @Before, @After를 모두 실행하는 형태이므로 타겟메소드의 리턴타입을 반환해야 한다.

 

4. 실행 클래스(main 함수가 있는 클래스)에서 bean으로 받아오는 클래스가 인터페이스를 구현하는 경우

  4-1 반드시 인터페이스 형으로 받아 메소드를 호출해야 정상동작한다.

  4-2 인터페이스 형이 아닌 경우 BeanNotOfRequiredTypeException 예외를 발생하게 된다.

// 설정 클래스
package pe.pilseong.aop_around.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration
@EnableAspectJAutoProxy
@ComponentScan(basePackages = "pe.pilseong.aop_around")
public class JavaConfig {}


// Aspect 클래스
package pe.pilseong.aop_around.aspect;

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 AroundAspect {
  
  @Around(value = "execution(* pe.pilseong.aop_around.service.*.*(..))")
  public Object afterGetFortuneAdvice(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println("afterGetFortuneAdvice is executed after " + joinPoint.getSignature().toShortString());
    
    long begin = System.currentTimeMillis();
    
    // 타겟 메소드의 실행하고 결과 값을 받아온다.
    Object result = joinPoint.proceed();
    
    long end = System.currentTimeMillis();
    
    System.out.println("Duration: " + (end - begin) / 1000.0 + " seconds\n");
    
    // 타겟 메소드의 리턴값을 다시 반환한다. 필요 시 수정도 가능하다.
    return result;
  }
}

// 더미 서비스
package pe.pilseong.aop_around.service;

import java.util.concurrent.TimeUnit;

import org.springframework.stereotype.Component;

@Component
public class BaseballCoachService {

  public String getFortune() {
    
    try {
      System.out.println(getClass() + " in getFoturne with no param");
      TimeUnit.SECONDS.sleep(2);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    
    return "You are gonna have a great day";
  }
  
  public String test() {
    return "I love it";
  }
}


// 실행 클래스이다
package pe.pilseong.aop_around;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import pe.pilseong.aop_around.config.JavaConfig;
import pe.pilseong.aop_around.service.BaseballCoachService;

public class App {
  public static void main(String[] args) {
    AnnotationConfigApplicationContext context 
      = new AnnotationConfigApplicationContext(JavaConfig.class);
   
    BaseballCoachService coach = context.getBean("baseballCoachService", BaseballCoachService.class);
    
    System.out.println(coach.getFortune());
    System.out.println(coach.test());
    
    context.close();
  }
}

// 실행결과
afterGetFortuneAdvice is executed around BaseballCoachService.getFortune()
class pe.pilseong.aop_around.service.BaseballCoachService in getFoturne with no param
Duration: 2.014 seconds

You are gonna have a great day
afterGetFortuneAdvice is executed around BaseballCoachService.test()
I love it
Duration: 0.001 seconds

 

5. 호출자에게 전파되지 않는 예외처리 예제 추가

  5-1 간결성을 위해 코드가 추가된 클래스만 아래에 붙였다.

  5-2 타겟 메소드를 try-catch로 처리 후 리턴 값을 생성해서 반환하면 호출자가 알 수 없는 형식으로 처리된다.

 

// 더미 서비스 클래스
@Component
public class BaseballCoachService {

  public String getFortune() {
    
    try {
      System.out.println(getClass() + " in getFoturne with no param");
      TimeUnit.SECONDS.sleep(2);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    
    return "You are gonna have a great day";
  }
  
  public String test() {
    return "I love it";
  }
  
  // 추가됨
  public String throwException() {
    throw new RuntimeException("Exception from throwException in BaseballCoachServce");
  }
}

// Aspect 클래스
@Aspect
@Component
public class AroundAspect {

  @Around(value = "execution(* pe.pilseong.aop_around.service.*.*(..))")
  public Object afterGetFortuneAdvice(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println("\n@Around afterGetFortuneAdvice is executed around " + joinPoint.getSignature().toShortString());

    long begin = System.currentTimeMillis();

    Object result = null;
    try {
      result = joinPoint.proceed();
    } catch (Exception e) {
      System.out.println("@Around afterGetFortuneAdvice" + e.getMessage());
      result = "Nothing really matters";
    }

    long end = System.currentTimeMillis();

    System.out.println("Duration: " + (end - begin) / 1000.0 + " seconds");

    return result;
  }
}

// 실행 클래스
public class App {
  public static void main(String[] args) {
    AnnotationConfigApplicationContext context 
      = new AnnotationConfigApplicationContext(JavaConfig.class);
   
    BaseballCoachService coach = context.getBean("baseballCoachService", BaseballCoachService.class);
    
    System.out.println(coach.getFortune());
    System.out.println(coach.test());
    
    // 추가됨
    System.out.println(coach.throwException());
    
    context.close();
  }
}


// 실행 결과
@Around afterGetFortuneAdvice is executed around BaseballCoachService.getFortune()
class pe.pilseong.aop_around.service.BaseballCoachService in getFoturne with no param
Duration: 2.023 seconds
You are gonna have a great day

@Around afterGetFortuneAdvice is executed around BaseballCoachService.test()
Duration: 0.0 seconds
I love it

@Around afterGetFortuneAdvice is executed around BaseballCoachService.throwException()
@Around afterGetFortuneAdviceException from throwException in BaseballCoachServce
Duration: 0.0 seconds
Nothing really matters

 

6. @Around에서 다시 예외를 던지는 예제

  6-1 5번 항목의 예제처럼 예외를 완전히 감추는 것도 가능하지만 처리 후 예외를 다시 던질 수도 있다.

  6-2 결과를 보면 advice 진입 후 예외 발생 시 catch 문이 호출되고 다시 예외가 전파되는 것을 확인 할 수 있다.

 

  // Aspect
  @Around(value = "execution(* pe.pilseong.aop_around.service.*.*(..))")
  public Object afterGetFortuneAdvice(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println("\n@Around afterGetFortuneAdvice is executed around " + joinPoint.getSignature().toShortString());
    
    try {
      // 정상적으로 결과가 반환 된 경우
      return joinPoint.proceed();
    } catch (Exception e) {
      // 예외 발생 시 여기서 예외를 처리 한 후 다시 throw로 예외를 발생시킨다.
      System.out.println("@Around afterGetFortuneAdvice" + e.getMessage());
      
      throw e;
    }
  }
  
  // 실행 결과
@Around afterGetFortuneAdvice is executed around BaseballCoachService.getFortune()
class pe.pilseong.aop_around.service.BaseballCoachService in getFoturne with no param
You are gonna have a great day
Exception in thread "main" 
@Around afterGetFortuneAdvice is executed around BaseballCoachService.test()
I love it

@Around afterGetFortuneAdvice is executed around BaseballCoachService.throwException()
@Around afterGetFortuneAdviceException from throwException in BaseballCoachServce
java.lang.RuntimeException: Exception from throwException in BaseballCoachServce
	at pe.pilseong.aop_around.service.BaseballCoachService.throwException(BaseballCoachService.java:27)
	at pe.pilseong.aop_around.service.BaseballCoachService$$FastClassBySpringCGLIB$$23270b6.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:771)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
	at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
	at pe.pilseong.aop_around.aspect.AroundAspect.afterGetFortuneAdvice(AroundAspect.java:38)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
	at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691)
	at pe.pilseong.aop_around.service.BaseballCoachService$$EnhancerBySpringCGLIB$$2f3df6aa.throwException(<generated>)
	at pe.pilseong.aop_around.App.main(App.java:21)