/*
* 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 java.io.NotSerializableException;
import java.io.ObjectStreamException;
import java.io.Serializable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.aop.TargetSource;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
/**
* Base class for {@link org.springframework.aop.TargetSource} implementations
* that are based on a Spring {@link org.springframework.beans.factory.BeanFactory},
* delegating to Spring-managed bean instances.
*
* <p>Subclasses can create prototype instances or lazily access a
* singleton target, for example. See {@link LazyInitTargetSource} and
* {@link AbstractPrototypeBasedTargetSource}'s subclasses for concrete strategies.
*
* <p>BeanFactory-based TargetSources are serializable. This involves
* disconnecting the current target and turning into a {@link SingletonTargetSource}.
*
* @author Juergen Hoeller
* @author Rod Johnson
* @since 1.1.4
* @see org.springframework.beans.factory.BeanFactory#getBean
* @see LazyInitTargetSource
* @see PrototypeTargetSource
* @see ThreadLocalTargetSource
* @see CommonsPoolTargetSource
*/
public abstract class AbstractBeanFactoryBasedTargetSource
implements TargetSource, BeanFactoryAware, Serializable {
/** use serialVersionUID from Spring 1.2.7 for interoperability */
private static final long serialVersionUID = -4721607536018568393L;
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
/** Name of the target bean we will create on each invocation */
private String targetBeanName;
/** Class of the target */
private Class targetClass;
/**
* BeanFactory that owns this TargetSource. We need to hold onto this
* reference so that we can create new prototype instances as necessary.
*/
private BeanFactory beanFactory;
/**
* Set the name of the target bean in the factory.
* <p>The target bean should not be a singleton, else the same instance will
* always be obtained from the factory, resulting in the same behavior as
* provided by {@link SingletonTargetSource}.
* @param targetBeanName name of the target bean in the BeanFactory
* that owns this interceptor
* @see SingletonTargetSource
*/
public void setTargetBeanName(String targetBeanName) {
this.targetBeanName = targetBeanName;
}
/**
* Return the name of the target bean in the factory.
*/
public String getTargetBeanName() {
return this.targetBeanName;
}
/**
* Specify the target class explicitly, to avoid any kind of access to the
* target bean (for example, to avoid initialization of a FactoryBean instance).
* <p>Default is to detect the type automatically, through a <code>getType</code>
* call on the BeanFactory (or even a full <code>getBean</code> call as fallback).
*/
public void setTargetClass(Class targetClass) {
this.targetClass = targetClass;
}
/**
* Set the owning BeanFactory. We need to save a reference so that we can
* use the <code>getBean</code> method on every invocation.
*/
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
if (this.targetBeanName == null) {
throw new IllegalStateException("Property'targetBeanName' is required");
}
this.beanFactory = beanFactory;
}
/**
* Return the owning BeanFactory.
*/
public BeanFactory getBeanFactory() {
return this.beanFactory;
}
public synchronized Class getTargetClass() {
if (this.targetClass == null && this.beanFactory != null) {
// Determine type of the target bean.
this.targetClass = this.beanFactory.getType(this.targetBeanName);
if (this.targetClass == null) {
if (logger.isTraceEnabled()) {
logger.trace("Getting bean with name '" + this.targetBeanName + "' in order to determine type");
}
this.targetClass = this.beanFactory.getBean(this.targetBeanName).getClass();
}
}
return this.targetClass;
}
public boolean isStatic() {
return false;
}
public void releaseTarget(Object target) throws Exception {
// Nothing to do here.
}
/**
* Copy configuration from the other AbstractBeanFactoryBasedTargetSource object.
* Subclasses should override this if they wish to expose it.
* @param other object to copy configuration from
*/
protected void copyFrom(AbstractBeanFactoryBasedTargetSource other) {
this.targetBeanName = other.targetBeanName;
this.targetClass = other.targetClass;
this.beanFactory = other.beanFactory;
}
/**
* Replaces this object with a SingletonTargetSource on serialization.
* Protected as otherwise it won't be invoked for subclasses.
* (The <code>writeReplace()</code> method must be visible to the class
* being serialized.)
* <p>With this implementation of this method, there is no need to mark
* non-serializable fields in this class or subclasses as transient.
*/
protected Object writeReplace() throws ObjectStreamException {
if (logger.isDebugEnabled()) {
logger.debug("Disconnecting TargetSource [" + this + "]");
}
try {
// Create disconnected SingletonTargetSource.
return new SingletonTargetSource(getTarget());
}
catch (Exception ex) {
logger.error("Cannot get target for disconnecting TargetSource [" + this + "]", ex);
throw new NotSerializableException(
"Cannot get target for disconnecting TargetSource [" + this + "]: " + ex);
}
}
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other == null || !getClass().equals(other.getClass())) {
return false;
}
AbstractBeanFactoryBasedTargetSource otherTargetSource = (AbstractBeanFactoryBasedTargetSource) other;
return (ObjectUtils.nullSafeEquals(this.beanFactory, otherTargetSource.beanFactory) &&
ObjectUtils.nullSafeEquals(this.targetBeanName, otherTargetSource.targetBeanName));
}
public int hashCode() {
int hashCode = getClass().hashCode();
hashCode = 13 * hashCode + ObjectUtils.nullSafeHashCode(this.beanFactory);
hashCode = 13 * hashCode + ObjectUtils.nullSafeHashCode(this.targetBeanName);
return hashCode;
}
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append(ClassUtils.getShortName(getClass()));
sb.append(" for target bean '").append(this.targetBeanName).append("'");
if (this.targetClass != null) {
sb.append(" of type [").append(this.targetClass.getName()).append("]");
}
return sb.toString();
}
}