/*
* 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.target;
import org.springframework.aop.support.DefaultIntroductionAdvisor;
import org.springframework.aop.support.DelegatingIntroductionInterceptor;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.DisposableBean;
/**
* Abstract base class for pooling {@link org.springframework.aop.TargetSource}
* implementations which maintain a pool of target instances, acquiring and
* releasing a target object from the pool for each method invocation.
* This abstract base class is independent of concrete pooling technology;
* see the subclass {@link CommonsPoolTargetSource} for a concrete example.
*
* <p>Subclasses must implement the {@link #getTarget} and
* {@link #releaseTarget} methods based on their chosen object pool.
* The {@link #newPrototypeInstance()} method inherited from
* {@link AbstractPrototypeBasedTargetSource} can be used to create objects
* in order to put them into the pool.
*
* <p>Subclasses must also implement some of the monitoring methods from the
* {@link PoolingConfig} interface. The {@link #getPoolingConfigMixin()} method
* makes these stats available on proxied objects through an IntroductionAdvisor.
*
* <p>This class implements the {@link org.springframework.beans.factory.DisposableBean}
* interface in order to force subclasses to implement a {@link #destroy()}
* method, closing down their object pool.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see #getTarget
* @see #releaseTarget
* @see #destroy
*/
public abstract class AbstractPoolingTargetSource extends AbstractPrototypeBasedTargetSource
implements PoolingConfig, DisposableBean {
/** The maximum size of the pool */
private int maxSize = -1;
/**
* Set the maximum size of the pool.
* Default is -1, indicating no size limit.
*/
public void setMaxSize(int maxSize) {
this.maxSize = maxSize;
}
/**
* Return the maximum size of the pool.
*/
public int getMaxSize() {
return this.maxSize;
}
@Override
public final void setBeanFactory(BeanFactory beanFactory) throws BeansException {
super.setBeanFactory(beanFactory);
try {
createPool();
}
catch (Throwable ex) {
throw new BeanInitializationException("Could not create instance pool for TargetSource", ex);
}
}
/**
* Create the pool.
* @throws Exception to avoid placing constraints on pooling APIs
*/
protected abstract void createPool() throws Exception;
/**
* Acquire an object from the pool.
* @return an object from the pool
* @throws Exception we may need to deal with checked exceptions from pool
* APIs, so we're forgiving with our exception signature
*/
public abstract Object getTarget() throws Exception;
/**
* Return the given object to the pool.
* @param target object that must have been acquired from the pool
* via a call to <code>getTarget()</code>
* @throws Exception to allow pooling APIs to throw exception
* @see #getTarget
*/
@Override
public abstract void releaseTarget(Object target) throws Exception;
/**
* Return an IntroductionAdvisor that providing a mixin
* exposing statistics about the pool maintained by this object.
*/
public DefaultIntroductionAdvisor getPoolingConfigMixin() {
DelegatingIntroductionInterceptor dii = new DelegatingIntroductionInterceptor(this);
return new DefaultIntroductionAdvisor(dii, PoolingConfig.class);
}
}