org.springframework.beans.factory.config.AbstractFactoryBean Maven / Gradle / Ivy
/*
* Copyright 2002-2004 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.config;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
/**
* Simple template superclass for FactoryBean implementations thats allows
* for creating a singleton or a prototype, depending on a flag.
*
* If the "singleton" flag is "true" (the default), this class will
* create once on initialization and subsequently return the singleton
* instance. Else, this class will create a new instance each time.
* Subclasses are responsible for implementing the abstract
* createInstance template method to actually create objects.
*
* @author Juergen Hoeller
* @author Keith Donald
* @since 1.0.2
*/
public abstract class AbstractFactoryBean implements FactoryBean, InitializingBean {
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
private boolean singleton = true;
private Object singletonInstance;
/**
* Set if a singleton should be created, or a new object
* on each request else. Default is true (a singleton).
*/
public final void setSingleton(boolean singleton) {
this.singleton = singleton;
}
public final boolean isSingleton() {
return singleton;
}
public final void afterPropertiesSet() throws Exception {
if (this.singleton) {
this.singletonInstance = createInstance();
}
}
public final Object getObject() throws Exception {
if (this.singleton) {
return this.singletonInstance;
}
else {
return createInstance();
}
}
/**
* Template method that subclasses must override to construct
* the object returned by this factory.
*
Invoked on initialization of this FactoryBean in case of
* a singleton; else, on each getObject() call.
* @return the object returned by this factory
* @throws Exception if an exception occured during object creation
* @see #getObject
*/
protected abstract Object createInstance() throws Exception;
}