/*
* Copyright 2002-2007 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
*
* http://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.aspectj.annotation;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.aspectj.lang.reflect.PerClauseKind;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.AspectJProxyUtils;
import org.springframework.aop.framework.AopConfigException;
import org.springframework.aop.framework.ProxyCreatorSupport;
import org.springframework.aop.support.AopUtils;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* AspectJ-based proxy factory, allowing for programmatic building
* of proxies which include AspectJ aspects (code style as well
* Java 5 annotation style).
*
* @author Rob Harrop
* @author Juergen Hoeller
* @author Ramnivas Laddad
* @since 2.0
* @see #addAspect(Object)
* @see #addAspect(Class)
* @see #getProxy()
* @see #getProxy(ClassLoader)
* @see org.springframework.aop.framework.ProxyFactory
*/
public class AspectJProxyFactory extends ProxyCreatorSupport {
/** Cache for singleton aspect instances */
private static final Map aspectCache = new HashMap();
private final AspectJAdvisorFactory aspectFactory = new ReflectiveAspectJAdvisorFactory();
/**
* Create a new AspectJProxyFactory.
*/
public AspectJProxyFactory() {
}
/**
* Create a new AspectJProxyFactory.
* <p>Will proxy all interfaces that the given target implements.
* @param target the target object to be proxied
*/
public AspectJProxyFactory(Object target) {
Assert.notNull(target, "Target object must not be null");
setInterfaces(ClassUtils.getAllInterfaces(target));
setTarget(target);
}
/**
* Create a new <code>AspectJProxyFactory</code>.
* No target, only interfaces. Must add interceptors.
*/
public AspectJProxyFactory(Class[] interfaces) {
setInterfaces(interfaces);
}
/**
* Add the supplied aspect instance to the chain. The type of the aspect instance
* supplied must be a singleton aspect. True singleton lifecycle is not honoured when
* using this method - the caller is responsible for managing the lifecycle of any
* aspects added in this way.
* @param aspectInstance the AspectJ aspect instance
*/
public void addAspect(Object aspectInstance) {
Class aspectClass = aspectInstance.getClass();
String aspectName = aspectClass.getName();
AspectMetadata am = createAspectMetadata(aspectClass, aspectName);
if (am.getAjType().getPerClause().getKind() != PerClauseKind.SINGLETON) {
throw new IllegalArgumentException(
"Aspect class [" + aspectClass.getName() + "] does not define a singleton aspect");
}
addAdvisorsFromAspectInstanceFactory(
new SingletonMetadataAwareAspectInstanceFactory(aspectInstance, aspectName));
}
/**
* Add an aspect of the supplied type to the end of the advice chain.
* @param aspectClass the AspectJ aspect class
*/
public void addAspect(Class aspectClass) {
String aspectName = aspectClass.getName();
AspectMetadata am = createAspectMetadata(aspectClass, aspectName);
MetadataAwareAspectInstanceFactory instanceFactory = createAspectInstanceFactory(am, aspectClass, aspectName);
addAdvisorsFromAspectInstanceFactory(instanceFactory);
}
/**
* Add all {@link Advisor Advisors} from the supplied {@link MetadataAwareAspectInstanceFactory}
* to the current chain. Exposes any special purpose {@link Advisor Advisors} if needed.
* @see #makeAdvisorChainAspectJCapableIfNecessary()
*/
private void addAdvisorsFromAspectInstanceFactory(MetadataAwareAspectInstanceFactory instanceFactory) {
List advisors = this.aspectFactory.getAdvisors(instanceFactory);
advisors = AopUtils.findAdvisorsThatCanApply(advisors, getTargetClass());
addAllAdvisors((Advisor[]) advisors.toArray(new Advisor[advisors.size()]));
makeAdvisorChainAspectJCapableIfNecessary();
}
/**
* Create an {@link AspectMetadata} instance for the supplied aspect type.
*/
private AspectMetadata createAspectMetadata(Class aspectClass, String aspectName) {
AspectMetadata am = new AspectMetadata(aspectClass, aspectName);
if (!am.getAjType().isAspect()) {
throw new IllegalArgumentException("Class [" + aspectClass.getName() + "] is not a valid aspect type");
}
return am;
}
/**
* Create a {@link MetadataAwareAspectInstanceFactory} for the supplied aspect type. If the aspect type
* has no per clause, then a {@link SingletonMetadataAwareAspectInstanceFactory} is returned, otherwise
* a {@link PrototypeAspectInstanceFactory} is returned.
*/
private MetadataAwareAspectInstanceFactory createAspectInstanceFactory(
AspectMetadata am, Class aspectClass, String aspectName) {
MetadataAwareAspectInstanceFactory instanceFactory = null;
if (am.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
// Create a shared aspect instance.
Object instance = getSingletonAspectInstance(aspectClass);
instanceFactory = new SingletonMetadataAwareAspectInstanceFactory(instance, aspectName);
}
else {
// Create a factory for independent aspect instances.
instanceFactory = new SimpleMetadataAwareAspectInstanceFactory(aspectClass, aspectName);
}
return instanceFactory;
}
/**
* Add any special-purpose {@link Advisor Advisors} needed for AspectJ support
* to the chain. {@link #updateAdvisorArray() Updates} the {@link Advisor} array
* and fires {@link #adviceChanged events}.
*/
private void makeAdvisorChainAspectJCapableIfNecessary() {
if (AspectJProxyUtils.makeAdvisorChainAspectJCapableIfNecessary(getAdvisorsInternal())) {
updateAdvisorArray();
adviceChanged();
}
}
/**
* Get the singleton aspect instance for the supplied aspect type. An instance
* is created if one cannot be found in the instance cache.
*/
private Object getSingletonAspectInstance(Class aspectClass) {
synchronized (aspectCache) {
Object instance = aspectCache.get(aspectClass);
if (instance != null) {
return instance;
}
try {
instance = aspectClass.newInstance();
aspectCache.put(aspectClass, instance);
return instance;
}
catch (InstantiationException ex) {
throw new AopConfigException("Unable to instantiate aspect class [" + aspectClass.getName() + "]", ex);
}
catch (IllegalAccessException ex) {
throw new AopConfigException("Cannot access aspect class [" + aspectClass.getName() + "]", ex);
}
}
}
/**
* Create a new proxy according to the settings in this factory.
* <p>Can be called repeatedly. Effect will vary if we've added
* or removed interfaces. Can add and remove interceptors.
* <p>Uses a default class loader: Usually, the thread context class loader
* (if necessary for proxy creation).
* @return the new proxy
*/
public <T> T getProxy() {
return (T) createAopProxy().getProxy();
}
/**
* Create a new proxy according to the settings in this factory.
* <p>Can be called repeatedly. Effect will vary if we've added
* or removed interfaces. Can add and remove interceptors.
* <p>Uses the given class loader (if necessary for proxy creation).
* @param classLoader the class loader to create the proxy with
* @return the new proxy
*/
public <T> T getProxy(ClassLoader classLoader) {
return (T) createAopProxy().getProxy(classLoader);
}
}