AOP 관련 용어와 기본 예제

[ParkYK]

※ Spring AOP 용어

Spring을 사용한 AOP에서는 다음과 같은 용어를 이해하는 것이 매우 중요하다

● Joinpoint : ‘클래스의 인스턴스 생성 시점’, ‘메소드 호출 시점’ 및 ‘예외 발생 시점’ 과 같이 어플리케이션을 실행할 때 특정 작업이 시작되는 시점을 의미.

● Advice : 조인포인트에 삽입되어 동작할 수 있는 코드를 말함.

● Pointcut : 여러 개의 조인포인트를 하나로 결합한(묶은) 것을 말함.

● Advisor : 어드바이스와 포인트컷을 하나로 묶어 취급한 것을 말함.

● Weaving : 어드바이스를 핵심 로직 코드에 삽입하는 것을 말함.

● Target : 핵심 로직을 구현하는 클래스.

● Aspect : 여러 객체에 공통으로 적용되는 공통 관점 사항을 말함.

기본 예제 실습 해 보기 --------------

MyCoreClass.java  

package pack;

public class MyCoreClass {

    public void foo() {

        System.out.println("핵심 메소드 foo()");

    }

    public void bar() {

        System.out.println("핵심 메소드 bar()");

    }

}

MyBean.java   

package pack;

public class MyBean {

    private MyCoreClass dep;

    public void setDep(MyCoreClass dep) {

    this.dep = dep;

    }

    public void execute() {

        dep.foo();

        dep.bar();

    }

}

MyAdvice.java     --- Aspect 

package pack;
import java.lang.reflect.Method;
import org.springframework.aop.MethodBeforeAdvice;
public class MyAdvice implements MethodBeforeAdvice {
   public void before(Method method, Object[] args, Object target) throws Throwable {
        System.out.println(method + " 전에 보안 처리");
   }
}

Main.java  

package pack;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
  public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("classpath:aoptest.xml");
      MyBean bean1 = (MyBean) context.getBean("myBean1");
      MyBean bean2 = (MyBean) context.getBean("myBean2");
      System.out.println("Bean 1 수행");
      bean1.execute();
      System.out.println("\nBean 2 수행");
      bean2.execute();
  }
}

aoptest.xml   

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"><bean id="myBean1" class="pack.MyBean">
<property name="dep">
  <ref local="target1" />
</property>
</bean>
<bean id="myBean2" class="pack.MyBean">
  <property name="dep">
    <ref local="target2" />
  </property>
</bean>
<bean id="myTarget" class="pack.MyCoreClass" />
<bean id="target1" class="org.springframework.aop.framework.ProxyFactoryBean">
  <property name="target">
    <ref local="myTarget" />
  </property>
  <property name="interceptorNames">
    <list>    <!-- advice를 직접 target에 적용 -->
       <value>advice</value>
    </list>
  </property>
</bean>
<bean id="target2" class="org.springframework.aop.framework.ProxyFactoryBean">
  <property name="target">
         <ref local="myTarget" />
  </property>
  <property name="interceptorNames">
       <list>        <!-- advice와 pointcut을 설정해서 적용 -->
          <value>advisor</value>
       </list>
  </property>
</bean>
<bean id="advice" class="pack.MyAdvice" />
  <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor">
       <property name="advice">
           <ref local="advice" />
       </property>
       <property name="pointcut">
          <bean class="org.springframework.aop.aspectj.AspectJExpression‎Pointcut">
       <property name="expression‎">
             <value>execution(* foo*(..))</value>        <!-- execution(* pack.*.*(..)) -->
       </property>
  </bean>
</property>
</bean>
</beans>

Annotation 사용 예제 --------------

Apple.java -  인터페이스

package aaa;

public interface Apple {

    public void coreProcess();

}

AppleImpl.java  

package aaa;

public class AppleImpl implements Apple {
    @Override public void coreProcess() { System.out.println("핵심 메소드 수행"); }
}

AnnotLoggingAspect.java  - advice bean

package aaa;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
@Aspect
public class AnnotLoggingAspect {
  @Around("execution(public * aaa.*.core*(..))")
  public void logging(ProceedingJoinPoint joinPoint) {
         String methodName = joinPoint.getSignature().getName();   // 핵심 메소드명 얻기

         try {
            System.out.println("before : " + methodName);
            joinPoint.proceed();
            System.out.println("after : " + methodName);
         } catch (Throwable e) {
         System.out.println("예외가 발생했어요!");
         }
  }
}

appContext.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:aop="http://www.springframework.org/schema/aop"xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">

    <aop:aspectj-autoproxy />  

    <bean id="apple" class="aaa.AppleImpl" /> 

    <bean class="aaa.AnnotLoggingAspect" />

</beans>

Main.java 

package aaa;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

       public static void main(String[] args) {

            String configLocation = "appContext.xml";

            ApplicationContext context = new ClassPathXmlApplicationContext( configLocation);

            Apple apple = (Apple) context.getBean("apple");

            apple.coreProcess();

       }

}

***** 수행 결과 *****

before : coreProcess 핵심 메소드 수행

after : coreProcess

참고 : 

http://mudchobo.tistory.com/252
http://isstory83.tistory.com/115