001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.aop.aspectj.annotation;
018
019import java.util.List;
020import java.util.Map;
021import java.util.concurrent.ConcurrentHashMap;
022
023import org.aspectj.lang.reflect.PerClauseKind;
024
025import org.springframework.aop.Advisor;
026import org.springframework.aop.aspectj.AspectJProxyUtils;
027import org.springframework.aop.aspectj.SimpleAspectInstanceFactory;
028import org.springframework.aop.framework.ProxyCreatorSupport;
029import org.springframework.aop.support.AopUtils;
030import org.springframework.core.annotation.AnnotationAwareOrderComparator;
031import org.springframework.util.Assert;
032import org.springframework.util.ClassUtils;
033
034/**
035 * AspectJ-based proxy factory, allowing for programmatic building
036 * of proxies which include AspectJ aspects (code style as well
037 * Java 5 annotation style).
038 *
039 * @author Rob Harrop
040 * @author Juergen Hoeller
041 * @author Ramnivas Laddad
042 * @since 2.0
043 * @see #addAspect(Object)
044 * @see #addAspect(Class)
045 * @see #getProxy()
046 * @see #getProxy(ClassLoader)
047 * @see org.springframework.aop.framework.ProxyFactory
048 */
049@SuppressWarnings("serial")
050public class AspectJProxyFactory extends ProxyCreatorSupport {
051
052        /** Cache for singleton aspect instances. */
053        private static final Map<Class<?>, Object> aspectCache = new ConcurrentHashMap<>();
054
055        private final AspectJAdvisorFactory aspectFactory = new ReflectiveAspectJAdvisorFactory();
056
057
058        /**
059         * Create a new AspectJProxyFactory.
060         */
061        public AspectJProxyFactory() {
062        }
063
064        /**
065         * Create a new AspectJProxyFactory.
066         * <p>Will proxy all interfaces that the given target implements.
067         * @param target the target object to be proxied
068         */
069        public AspectJProxyFactory(Object target) {
070                Assert.notNull(target, "Target object must not be null");
071                setInterfaces(ClassUtils.getAllInterfaces(target));
072                setTarget(target);
073        }
074
075        /**
076         * Create a new {@code AspectJProxyFactory}.
077         * No target, only interfaces. Must add interceptors.
078         */
079        public AspectJProxyFactory(Class<?>... interfaces) {
080                setInterfaces(interfaces);
081        }
082
083
084        /**
085         * Add the supplied aspect instance to the chain. The type of the aspect instance
086         * supplied must be a singleton aspect. True singleton lifecycle is not honoured when
087         * using this method - the caller is responsible for managing the lifecycle of any
088         * aspects added in this way.
089         * @param aspectInstance the AspectJ aspect instance
090         */
091        public void addAspect(Object aspectInstance) {
092                Class<?> aspectClass = aspectInstance.getClass();
093                String aspectName = aspectClass.getName();
094                AspectMetadata am = createAspectMetadata(aspectClass, aspectName);
095                if (am.getAjType().getPerClause().getKind() != PerClauseKind.SINGLETON) {
096                        throw new IllegalArgumentException(
097                                        "Aspect class [" + aspectClass.getName() + "] does not define a singleton aspect");
098                }
099                addAdvisorsFromAspectInstanceFactory(
100                                new SingletonMetadataAwareAspectInstanceFactory(aspectInstance, aspectName));
101        }
102
103        /**
104         * Add an aspect of the supplied type to the end of the advice chain.
105         * @param aspectClass the AspectJ aspect class
106         */
107        public void addAspect(Class<?> aspectClass) {
108                String aspectName = aspectClass.getName();
109                AspectMetadata am = createAspectMetadata(aspectClass, aspectName);
110                MetadataAwareAspectInstanceFactory instanceFactory = createAspectInstanceFactory(am, aspectClass, aspectName);
111                addAdvisorsFromAspectInstanceFactory(instanceFactory);
112        }
113
114
115        /**
116         * Add all {@link Advisor Advisors} from the supplied {@link MetadataAwareAspectInstanceFactory}
117         * to the current chain. Exposes any special purpose {@link Advisor Advisors} if needed.
118         * @see AspectJProxyUtils#makeAdvisorChainAspectJCapableIfNecessary(List)
119         */
120        private void addAdvisorsFromAspectInstanceFactory(MetadataAwareAspectInstanceFactory instanceFactory) {
121                List<Advisor> advisors = this.aspectFactory.getAdvisors(instanceFactory);
122                Class<?> targetClass = getTargetClass();
123                Assert.state(targetClass != null, "Unresolvable target class");
124                advisors = AopUtils.findAdvisorsThatCanApply(advisors, targetClass);
125                AspectJProxyUtils.makeAdvisorChainAspectJCapableIfNecessary(advisors);
126                AnnotationAwareOrderComparator.sort(advisors);
127                addAdvisors(advisors);
128        }
129
130        /**
131         * Create an {@link AspectMetadata} instance for the supplied aspect type.
132         */
133        private AspectMetadata createAspectMetadata(Class<?> aspectClass, String aspectName) {
134                AspectMetadata am = new AspectMetadata(aspectClass, aspectName);
135                if (!am.getAjType().isAspect()) {
136                        throw new IllegalArgumentException("Class [" + aspectClass.getName() + "] is not a valid aspect type");
137                }
138                return am;
139        }
140
141        /**
142         * Create a {@link MetadataAwareAspectInstanceFactory} for the supplied aspect type. If the aspect type
143         * has no per clause, then a {@link SingletonMetadataAwareAspectInstanceFactory} is returned, otherwise
144         * a {@link PrototypeAspectInstanceFactory} is returned.
145         */
146        private MetadataAwareAspectInstanceFactory createAspectInstanceFactory(
147                        AspectMetadata am, Class<?> aspectClass, String aspectName) {
148
149                MetadataAwareAspectInstanceFactory instanceFactory;
150                if (am.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
151                        // Create a shared aspect instance.
152                        Object instance = getSingletonAspectInstance(aspectClass);
153                        instanceFactory = new SingletonMetadataAwareAspectInstanceFactory(instance, aspectName);
154                }
155                else {
156                        // Create a factory for independent aspect instances.
157                        instanceFactory = new SimpleMetadataAwareAspectInstanceFactory(aspectClass, aspectName);
158                }
159                return instanceFactory;
160        }
161
162        /**
163         * Get the singleton aspect instance for the supplied aspect type. An instance
164         * is created if one cannot be found in the instance cache.
165         */
166        private Object getSingletonAspectInstance(Class<?> aspectClass) {
167                // Quick check without a lock...
168                Object instance = aspectCache.get(aspectClass);
169                if (instance == null) {
170                        synchronized (aspectCache) {
171                                // To be safe, check within full lock now...
172                                instance = aspectCache.get(aspectClass);
173                                if (instance == null) {
174                                        instance = new SimpleAspectInstanceFactory(aspectClass).getAspectInstance();
175                                        aspectCache.put(aspectClass, instance);
176                                }
177                        }
178                }
179                return instance;
180        }
181
182
183        /**
184         * Create a new proxy according to the settings in this factory.
185         * <p>Can be called repeatedly. Effect will vary if we've added
186         * or removed interfaces. Can add and remove interceptors.
187         * <p>Uses a default class loader: Usually, the thread context class loader
188         * (if necessary for proxy creation).
189         * @return the new proxy
190         */
191        @SuppressWarnings("unchecked")
192        public <T> T getProxy() {
193                return (T) createAopProxy().getProxy();
194        }
195
196        /**
197         * Create a new proxy according to the settings in this factory.
198         * <p>Can be called repeatedly. Effect will vary if we've added
199         * or removed interfaces. Can add and remove interceptors.
200         * <p>Uses the given class loader (if necessary for proxy creation).
201         * @param classLoader the class loader to create the proxy with
202         * @return the new proxy
203         */
204        @SuppressWarnings("unchecked")
205        public <T> T getProxy(ClassLoader classLoader) {
206                return (T) createAopProxy().getProxy(classLoader);
207        }
208
209}