Java tutorial
/* * 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. * * <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. * <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. * <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. * <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. * <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. * @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 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 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 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 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 {@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? * <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? * <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. * @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? * <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 {@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. * @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); } } }