https://github.com/spring-projects/spring-framework: Spring AOP (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.support;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import org.springframework.aop.Advisor;
import org.springframework.aop.AopInvocationException;
import org.springframework.aop.IntroductionAdvisor;
import org.springframework.aop.IntroductionAwareMethodMatcher;
import org.springframework.aop.MethodMatcher;
import org.springframework.aop.Pointcut;
import org.springframework.aop.PointcutAdvisor;
import org.springframework.aop.SpringProxy;
import org.springframework.aop.TargetClassAware;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.MethodIntrospector;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;


Utility methods for AOP support code.

Mainly for internal use within Spring's AOP support.

See AopProxyUtils for a collection of framework-specific AOP utility methods which depend on internals of Spring's AOP framework implementation. 
Author:Rod Johnson, Juergen Hoeller, Rob Harrop
See Also:
/**
 * Utility methods for AOP support code.
 *
 * <p>Mainly for internal use within Spring's AOP support.
 *
 * <p>See {@link org.springframework.aop.framework.AopProxyUtils} for a
 * collection of framework-specific AOP utility methods which depend
 * on internals of Spring's AOP framework implementation.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @see org.springframework.aop.framework.AopProxyUtils
 */
public abstract class AopUtils {

	
Check whether the given object is a JDK dynamic proxy or a CGLIB proxy.

This method additionally checks if the given object is an instance of SpringProxy. 
Params:
  • object – the object to check
See Also:
/**
	 * Check whether the given object is a JDK dynamic proxy or a CGLIB proxy.
	 * <p>This method additionally checks if the given object is an instance
	 * of {@link SpringProxy}.
	 * @param object the object to check
	 * @see #isJdkDynamicProxy
	 * @see #isCglibProxy
	 */
	public static boolean isAopProxy(@Nullable Object object) {
		return (object instanceof SpringProxy && (Proxy.isProxyClass(object.getClass()) ||
				object.getClass().getName().contains(ClassUtils.CGLIB_CLASS_SEPARATOR)));
	}

	
Check whether the given object is a JDK dynamic proxy.

This method goes beyond the implementation of Proxy.isProxyClass(Class<?>) by additionally checking if the given object is an instance of SpringProxy. 
Params:
  • object – the object to check
See Also:
/**
	 * Check whether the given object is a JDK dynamic proxy.
	 * <p>This method goes beyond the implementation of
	 * {@link Proxy#isProxyClass(Class)} by additionally checking if the
	 * given object is an instance of {@link SpringProxy}.
	 * @param object the object to check
	 * @see java.lang.reflect.Proxy#isProxyClass
	 */
	public static boolean isJdkDynamicProxy(@Nullable Object object) {
		return (object instanceof SpringProxy && Proxy.isProxyClass(object.getClass()));
	}

	
Check whether the given object is a CGLIB proxy.

This method goes beyond the implementation of ClassUtils.isCglibProxy(Object) by additionally checking if the given object is an instance of SpringProxy. 
Params:
  • object – the object to check
See Also:
/**
	 * Check whether the given object is a CGLIB proxy.
	 * <p>This method goes beyond the implementation of
	 * {@link ClassUtils#isCglibProxy(Object)} by additionally checking if
	 * the given object is an instance of {@link SpringProxy}.
	 * @param object the object to check
	 * @see ClassUtils#isCglibProxy(Object)
	 */
	public static boolean isCglibProxy(@Nullable Object object) {
		return (object instanceof SpringProxy &&
				object.getClass().getName().contains(ClassUtils.CGLIB_CLASS_SEPARATOR));
	}

	
Determine the target class of the given bean instance which might be an AOP proxy.

Returns the target class for an AOP proxy or the plain class otherwise.

Params:
  • candidate – the instance to check (might be an AOP proxy)
See Also:
Returns:the target class (or the plain class of the given object as fallback; never null)
/**
	 * Determine the target class of the given bean instance which might be an AOP proxy.
	 * <p>Returns the target class for an AOP proxy or the plain class otherwise.
	 * @param candidate the instance to check (might be an AOP proxy)
	 * @return the target class (or the plain class of the given object as fallback;
	 * never {@code null})
	 * @see org.springframework.aop.TargetClassAware#getTargetClass()
	 * @see org.springframework.aop.framework.AopProxyUtils#ultimateTargetClass(Object)
	 */
	public static Class<?> getTargetClass(Object candidate) {
		Assert.notNull(candidate, "Candidate object must not be null");
		Class<?> result = null;
		if (candidate instanceof TargetClassAware) {
			result = ((TargetClassAware) candidate).getTargetClass();
		}
		if (result == null) {
			result = (isCglibProxy(candidate) ? candidate.getClass().getSuperclass() : candidate.getClass());
		}
		return result;
	}

	
Select an invocable method on the target type: either the given method itself
if actually exposed on the target type, or otherwise a corresponding method
on one of the target type's interfaces or on the target type itself.

Params:
  • method – the method to check
  • targetType – the target type to search methods on (typically an AOP proxy)
Throws:
  • IllegalStateException – if the given method is not invocable on the given
target type (typically due to a proxy mismatch)
See Also:
Returns:a corresponding invocable method on the target type
Since:4.3
/**
	 * Select an invocable method on the target type: either the given method itself
	 * if actually exposed on the target type, or otherwise a corresponding method
	 * on one of the target type's interfaces or on the target type itself.
	 * @param method the method to check
	 * @param targetType the target type to search methods on (typically an AOP proxy)
	 * @return a corresponding invocable method on the target type
	 * @throws IllegalStateException if the given method is not invocable on the given
	 * target type (typically due to a proxy mismatch)
	 * @since 4.3
	 * @see MethodIntrospector#selectInvocableMethod(Method, Class)
	 */
	public static Method selectInvocableMethod(Method method, @Nullable Class<?> targetType) {
		if (targetType == null) {
			return method;
		}
		Method methodToUse = MethodIntrospector.selectInvocableMethod(method, targetType);
		if (Modifier.isPrivate(methodToUse.getModifiers()) && !Modifier.isStatic(methodToUse.getModifiers()) &&
				SpringProxy.class.isAssignableFrom(targetType)) {
			throw new IllegalStateException(String.format(
					"Need to invoke method '%s' found on proxy for target class '%s' but cannot " +
					"be delegated to target bean. Switch its visibility to package or protected.",
					method.getName(), method.getDeclaringClass().getSimpleName()));
		}
		return methodToUse;
	}

	
Determine whether the given method is an "equals" method.

See Also:
  • equals.equals
/**
	 * Determine whether the given method is an "equals" method.
	 * @see java.lang.Object#equals
	 */
	public static boolean isEqualsMethod(@Nullable Method method) {
		return ReflectionUtils.isEqualsMethod(method);
	}

	
Determine whether the given method is a "hashCode" method.

See Also:
  • hashCode.hashCode
/**
	 * Determine whether the given method is a "hashCode" method.
	 * @see java.lang.Object#hashCode
	 */
	public static boolean isHashCodeMethod(@Nullable Method method) {
		return ReflectionUtils.isHashCodeMethod(method);
	}

	
Determine whether the given method is a "toString" method.

See Also:
  • toString.toString()
/**
	 * Determine whether the given method is a "toString" method.
	 * @see java.lang.Object#toString()
	 */
	public static boolean isToStringMethod(@Nullable Method method) {
		return ReflectionUtils.isToStringMethod(method);
	}

	
Determine whether the given method is a "finalize" method.

See Also:
  • finalize.finalize()
/**
	 * Determine whether the given method is a "finalize" method.
	 * @see java.lang.Object#finalize()
	 */
	public static boolean isFinalizeMethod(@Nullable Method method) {
		return (method != null && method.getName().equals("finalize") &&
				method.getParameterCount() == 0);
	}

	
Given a method, which may come from an interface, and a target class used in the current AOP invocation, find the corresponding target method if there is one. E.g. the method may be IFoo.bar() and the target class may be DefaultFoo. In this case, the method may be DefaultFoo.bar(). This enables attributes on that method to be found. 
NOTE: In contrast to ClassUtils.getMostSpecificMethod, this method resolves Java 5 bridge methods in order to retrieve attributes from the original method definition.

Params:
  • method – the method to be invoked, which may come from an interface
  • targetClass – the target class for the current invocation. May be null or may not even implement the method.
See Also:
Returns:the specific target method, or the original method if the targetClass doesn't implement it or is null
/**
	 * Given a method, which may come from an interface, and a target class used
	 * in the current AOP invocation, find the corresponding target method if there
	 * is one. E.g. the method may be {@code IFoo.bar()} and the target class
	 * may be {@code DefaultFoo}. In this case, the method may be
	 * {@code DefaultFoo.bar()}. This enables attributes on that method to be found.
	 * <p><b>NOTE:</b> In contrast to {@link org.springframework.util.ClassUtils#getMostSpecificMethod},
	 * this method resolves Java 5 bridge methods in order to retrieve attributes
	 * from the <i>original</i> method definition.
	 * @param method the method to be invoked, which may come from an interface
	 * @param targetClass the target class for the current invocation.
	 * May be {@code null} or may not even implement the method.
	 * @return the specific target method, or the original method if the
	 * {@code targetClass} doesn't implement it or is {@code null}
	 * @see org.springframework.util.ClassUtils#getMostSpecificMethod
	 */
	public static Method getMostSpecificMethod(Method method, @Nullable Class<?> targetClass) {
		Class<?> specificTargetClass = (targetClass != null ? ClassUtils.getUserClass(targetClass) : null);
		Method resolvedMethod = ClassUtils.getMostSpecificMethod(method, specificTargetClass);
		// If we are dealing with method with generic parameters, find the original method.
		return BridgeMethodResolver.findBridgedMethod(resolvedMethod);
	}

	
Can the given pointcut apply at all on the given class?

This is an important test as it can be used to optimize
out a pointcut for a class.

Params:
  • pc – the static or dynamic pointcut to check
  • targetClass – the class to test
Returns:whether the pointcut can apply on any method
/**
	 * Can the given pointcut apply at all on the given class?
	 * <p>This is an important test as it can be used to optimize
	 * out a pointcut for a class.
	 * @param pc the static or dynamic pointcut to check
	 * @param targetClass the class to test
	 * @return whether the pointcut can apply on any method
	 */
	public static boolean canApply(Pointcut pc, Class<?> targetClass) {
		return canApply(pc, targetClass, false);
	}

	
Can the given pointcut apply at all on the given class?

This is an important test as it can be used to optimize
out a pointcut for a class.

Params:
  • pc – the static or dynamic pointcut to check
  • targetClass – the class to test
  • hasIntroductions – whether or not the advisor chain
for this bean includes any introductions
Returns:whether the pointcut can apply on any method
/**
	 * Can the given pointcut apply at all on the given class?
	 * <p>This is an important test as it can be used to optimize
	 * out a pointcut for a class.
	 * @param pc the static or dynamic pointcut to check
	 * @param targetClass the class to test
	 * @param hasIntroductions whether or not the advisor chain
	 * for this bean includes any introductions
	 * @return whether the pointcut can apply on any method
	 */
	public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
		Assert.notNull(pc, "Pointcut must not be null");
		if (!pc.getClassFilter().matches(targetClass)) {
			return false;
		}

		MethodMatcher methodMatcher = pc.getMethodMatcher();
		if (methodMatcher == MethodMatcher.TRUE) {
			// No need to iterate the methods if we're matching any method anyway...
			return true;
		}

		IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
		if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
			introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
		}

		Set<Class<?>> classes = new LinkedHashSet<>();
		if (!Proxy.isProxyClass(targetClass)) {
			classes.add(ClassUtils.getUserClass(targetClass));
		}
		classes.addAll(ClassUtils.getAllInterfacesForClassAsSet(targetClass));

		for (Class<?> clazz : classes) {
			Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
			for (Method method : methods) {
				if (introductionAwareMethodMatcher != null ?
						introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions) :
						methodMatcher.matches(method, targetClass)) {
					return true;
				}
			}
		}

		return false;
	}

	
Can the given advisor apply at all on the given class?
This is an important test as it can be used to optimize
out a advisor for a class.

Params:
  • advisor – the advisor to check
  • targetClass – class we're testing
Returns:whether the pointcut can apply on any method
/**
	 * Can the given advisor apply at all on the given class?
	 * This is an important test as it can be used to optimize
	 * out a advisor for a class.
	 * @param advisor the advisor to check
	 * @param targetClass class we're testing
	 * @return whether the pointcut can apply on any method
	 */
	public static boolean canApply(Advisor advisor, Class<?> targetClass) {
		return canApply(advisor, targetClass, false);
	}

	
Can the given advisor apply at all on the given class?

This is an important test as it can be used to optimize out a advisor for a class.
This version also takes into account introductions (for IntroductionAwareMethodMatchers).

Params:
  • advisor – the advisor to check
  • targetClass – class we're testing
  • hasIntroductions – whether or not the advisor chain for this bean includes
any introductions
Returns:whether the pointcut can apply on any method
/**
	 * Can the given advisor apply at all on the given class?
	 * <p>This is an important test as it can be used to optimize out a advisor for a class.
	 * This version also takes into account introductions (for IntroductionAwareMethodMatchers).
	 * @param advisor the advisor to check
	 * @param targetClass class we're testing
	 * @param hasIntroductions whether or not the advisor chain for this bean includes
	 * any introductions
	 * @return whether the pointcut can apply on any method
	 */
	public static boolean canApply(Advisor advisor, Class<?> targetClass, boolean hasIntroductions) {
		if (advisor instanceof IntroductionAdvisor) {
			return ((IntroductionAdvisor) advisor).getClassFilter().matches(targetClass);
		}
		else if (advisor instanceof PointcutAdvisor) {
			PointcutAdvisor pca = (PointcutAdvisor) advisor;
			return canApply(pca.getPointcut(), targetClass, hasIntroductions);
		}
		else {
			// It doesn't have a pointcut so we assume it applies.
			return true;
		}
	}

	
Determine the sublist of the candidateAdvisors list that is applicable to the given class. 
Params:
  • candidateAdvisors – the Advisors to evaluate
  • clazz – the target class
Returns:sublist of Advisors that can apply to an object of the given class
(may be the incoming List as-is)
/**
	 * Determine the sublist of the {@code candidateAdvisors} list
	 * that is applicable to the given class.
	 * @param candidateAdvisors the Advisors to evaluate
	 * @param clazz the target class
	 * @return sublist of Advisors that can apply to an object of the given class
	 * (may be the incoming List as-is)
	 */
	public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvisors, Class<?> clazz) {
		if (candidateAdvisors.isEmpty()) {
			return candidateAdvisors;
		}
		List<Advisor> eligibleAdvisors = new ArrayList<>();
		for (Advisor candidate : candidateAdvisors) {
			if (candidate instanceof IntroductionAdvisor && canApply(candidate, clazz)) {
				eligibleAdvisors.add(candidate);
			}
		}
		boolean hasIntroductions = !eligibleAdvisors.isEmpty();
		for (Advisor candidate : candidateAdvisors) {
			if (candidate instanceof IntroductionAdvisor) {
				// already processed
				continue;
			}
			if (canApply(candidate, clazz, hasIntroductions)) {
				eligibleAdvisors.add(candidate);
			}
		}
		return eligibleAdvisors;
	}

	
Invoke the given target via reflection, as part of an AOP method invocation.

Params:
  • target – the target object
  • method – the method to invoke
  • args – the arguments for the method
Throws:
Returns:the invocation result, if any
/**
	 * Invoke the given target via reflection, as part of an AOP method invocation.
	 * @param target the target object
	 * @param method the method to invoke
	 * @param args the arguments for the method
	 * @return the invocation result, if any
	 * @throws Throwable if thrown by the target method
	 * @throws org.springframework.aop.AopInvocationException in case of a reflection error
	 */
	@Nullable
	public static Object invokeJoinpointUsingReflection(@Nullable Object target, Method method, Object[] args)
			throws Throwable {

		// Use reflection to invoke the method.
		try {
			ReflectionUtils.makeAccessible(method);
			return method.invoke(target, args);
		}
		catch (InvocationTargetException ex) {
			// Invoked method threw a checked exception.
			// We must rethrow it. The client won't see the interceptor.
			throw ex.getTargetException();
		}
		catch (IllegalArgumentException ex) {
			throw new AopInvocationException("AOP configuration seems to be invalid: tried calling method [" +
					method + "] on target [" + target + "]", ex);
		}
		catch (IllegalAccessException ex) {
			throw new AopInvocationException("Could not access method [" + method + "]", ex);
		}
	}

}