/*
* Copyright 2002-2008 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.beans.factory.support;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Map;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanCurrentlyInCreationException;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.FactoryBeanNotInitializedException;
import org.springframework.core.CollectionFactory;
/**
* Support base class for singleton registries which need to handle
* {@link org.springframework.beans.factory.FactoryBean} instances,
* integrated with {@link DefaultSingletonBeanRegistry}'s singleton management.
*
* <p>Serves as base class for {@link AbstractBeanFactory}.
*
* @author Juergen Hoeller
* @since 2.5.1
*/
public abstract class FactoryBeanRegistrySupport extends DefaultSingletonBeanRegistry {
/** Cache of singleton objects created by FactoryBeans: FactoryBean name --> object */
private final Map factoryBeanObjectCache = CollectionFactory.createConcurrentMapIfPossible(16);
/**
* Determine the type for the given FactoryBean.
* @param factoryBean the FactoryBean instance to check
* @return the FactoryBean's object type,
* or <code>null</code> if the type cannot be determined yet
*/
protected Class getTypeForFactoryBean(FactoryBean factoryBean) {
try {
return factoryBean.getObjectType();
}
catch (Throwable ex) {
// Thrown from the FactoryBean's getObjectType implementation.
logger.warn("FactoryBean threw exception from getObjectType, despite the contract saying " +
"that it should return null if the type of its object cannot be determined yet", ex);
return null;
}
}
/**
* Obtain an object to expose from the given FactoryBean, if available
* in cached form. Quick check for minimal synchronization.
* @param beanName the name of the bean
* @return the object obtained from the FactoryBean,
* or <code>null</code> if not available
*/
protected Object getCachedObjectForFactoryBean(String beanName) {
Object object = this.factoryBeanObjectCache.get(beanName);
return (object != NULL_OBJECT ? object : null);
}
/**
* Obtain an object to expose from the given FactoryBean.
* @param factory the FactoryBean instance
* @param beanName the name of the bean
* @param shouldPostProcess whether the bean is subject for post-processing
* @return the object obtained from the FactoryBean
* @throws BeanCreationException if FactoryBean object creation failed
* @see org.springframework.beans.factory.FactoryBean#getObject()
*/
protected Object getObjectFromFactoryBean(FactoryBean factory, String beanName, boolean shouldPostProcess) {
if (factory.isSingleton() && containsSingleton(beanName)) {
synchronized (getSingletonMutex()) {
Object object = this.factoryBeanObjectCache.get(beanName);
if (object == null) {
object = doGetObjectFromFactoryBean(factory, beanName, shouldPostProcess);
this.factoryBeanObjectCache.put(beanName, (object != null ? object : NULL_OBJECT));
}
return (object != NULL_OBJECT ? object : null);
}
}
else {
return doGetObjectFromFactoryBean(factory, beanName, shouldPostProcess);
}
}
/**
* Obtain an object to expose from the given FactoryBean.
* @param factory the FactoryBean instance
* @param beanName the name of the bean
* @param shouldPostProcess whether the bean is subject for post-processing
* @return the object obtained from the FactoryBean
* @throws BeanCreationException if FactoryBean object creation failed
* @see org.springframework.beans.factory.FactoryBean#getObject()
*/
private Object doGetObjectFromFactoryBean(
final FactoryBean factory, final String beanName, final boolean shouldPostProcess)
throws BeanCreationException {
AccessControlContext acc = AccessController.getContext();
return AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
Object object;
try {
object = factory.getObject();
}
catch (FactoryBeanNotInitializedException ex) {
throw new BeanCurrentlyInCreationException(beanName, ex.toString());
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);
}
// Do not accept a null value for a FactoryBean that's not fully
// initialized yet: Many FactoryBeans just return null then.
if (object == null && isSingletonCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(
beanName, "FactoryBean which is currently in creation returned null from getObject");
}
if (object != null && shouldPostProcess) {
try {
object = postProcessObjectFromFactoryBean(object, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "Post-processing of the FactoryBean's object failed", ex);
}
}
return object;
}
}, acc);
}
/**
* Post-process the given object that has been obtained from the FactoryBean.
* The resulting object will get exposed for bean references.
* <p>The default implementation simply returns the given object as-is.
* Subclasses may override this, for example, to apply post-processors.
* @param object the object obtained from the FactoryBean.
* @param beanName the name of the bean
* @return the object to expose
* @throws org.springframework.beans.BeansException if any post-processing failed
*/
protected Object postProcessObjectFromFactoryBean(Object object, String beanName) throws BeansException {
return object;
}
/**
* Get a FactoryBean for the given bean if possible.
* @param beanName the name of the bean
* @param beanInstance the corresponding bean instance
* @return the bean instance as FactoryBean
* @throws BeansException if the given bean cannot be exposed as a FactoryBean
*/
protected FactoryBean getFactoryBean(String beanName, Object beanInstance) throws BeansException {
if (!(beanInstance instanceof FactoryBean)) {
throw new BeanCreationException(beanName,
"Bean instance of type [" + beanInstance.getClass() + "] is not a FactoryBean");
}
return (FactoryBean) beanInstance;
}
/**
* Overridden to clear the FactoryBean object cache as well.
*/
protected void removeSingleton(String beanName) {
super.removeSingleton(beanName);
this.factoryBeanObjectCache.remove(beanName);
}
}