Spring ‐ 스프링이 지원하는 프록시 - thought-corner/Backend-PlayGround GitHub Wiki

public interface AdvisorChainFactory {

	/**
	 * Determine a list of {@link org.aopalliance.intercept.MethodInterceptor} objects
	 * for the given advisor chain configuration.
	 * @param config the AOP configuration in the form of an Advised object
	 * @param method the proxied method
	 * @param targetClass the target class (may be {@code null} to indicate a proxy without
	 * target object, in which case the method's declaring class is the next best option)
	 * @return a List of MethodInterceptors (may also include InterceptorAndDynamicMethodMatchers)
	 */
	List<Object> getInterceptorsAndDynamicInterceptionAdvice(Advised config, Method method, @Nullable Class<?> targetClass);

}

public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
        Advised config, Method method, @Nullable Class<?> targetClass) {
    
    AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
    // ... 중략 ...
    for (Advisor advisor : config.getAdvisors()) {
        // 여기서 AdvisorAdapterRegistry를 통해 
        // 우리가 만든 Advice를 MethodInterceptor(공통 규격)로 변환(Adapt)합니다.
        MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
        interceptorsList.addAll(Arrays.asList(interceptors));
    }
    return interceptorsList;
}

final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializable {

    @Override
    @Nullable
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
        
        // 체인이 비어있으면 실제 타겟 메서드 직접 호출
        if (chain.isEmpty()) {
            retVal = AopUtils.invokeJoinpointUsingReflection(target, method, args);
        } else {
            // 체인이 있으면 MethodInvocation을 생성하여 Advice 실행 (Advice 호출 지점)
            MethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
            retVal = invocation.proceed();
        }
        return retVal;
    }
}

public class DynamicAdvisedInterceptor implements MethodInterceptor {

    private final AdvisedSupport advised; // 프록시 설정 정보 (Advice, Pointcut 등)

    public DynamicAdvisedInterceptor(AdvisedSupport advised) {
        this.advised = advised;
    }

    @Override
    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
        Object target = advised.getTargetSource().getTarget();
        List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, target.getClass());

        Object retVal;
        if (chain.isEmpty()) {
            // 1. 적용할 Advice(인터셉터)가 없으면 바로 타겟 호출
            retVal = proxy.invoke(target, args);
        } else {
            // 2. Advice가 있으면 MethodInvocation을 생성하여 체인 실행
            // 여기서 우리가 만든 Advice(MethodInterceptor)들이 순차적으로 실행됨
            MethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, method, args, target.getClass(), chain);
            retVal = invocation.proceed();
        }
        
        return retVal;
    }
}

public interface Pointcut {

    /**
     * 클래스가 일치하는지 확인하는 필터를 반환합니다.
     * @return the ClassFilter (never {@code null})
     */
    ClassFilter getClassFilter();

    /**
     * 메서드가 일치하는지 확인하는 매처를 반환합니다.
     * @return the MethodMatcher (never {@code null})
     */
    MethodMatcher getMethodMatcher();

    /**
     * 항상 True를 반환하는 기본 포인트컷 인스턴스입니다.
     * 모든 클래스와 메서드에 매칭하고자 할 때 사용됩니다.
     */
    Pointcut TRUE = TruePointcut.INSTANCE;

}