/*
* Copyright 2002-2009 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.orm.jdo;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Proxy for a target JDO {@link javax.jdo.PersistenceManagerFactory},
* returning the current thread-bound PersistenceManager (the Spring-managed
* transactional PersistenceManager or the single OpenPersistenceManagerInView
* PersistenceManager) on getPersistenceManager()
, if any.
*
*
Essentially, getPersistenceManager()
calls get seamlessly
* forwarded to {@link PersistenceManagerFactoryUtils#getPersistenceManager}.
* Furthermore, PersistenceManager.close
calls get forwarded to
* {@link PersistenceManagerFactoryUtils#releasePersistenceManager}.
*
*
The main advantage of this proxy is that it allows DAOs to work with a * plain JDO PersistenceManagerFactory reference, while still participating in * Spring's (or a J2EE server's) resource and transaction management. DAOs will * only rely on the JDO API in such a scenario, without any Spring dependencies. * *
Note that the behavior of this proxy matches the behavior that the JDO spec * defines for a PersistenceManagerFactory as exposed by a JCA connector, when * deployed in a J2EE server. Hence, DAOs could seamlessly switch between a JNDI * PersistenceManagerFactory and this proxy for a local PersistenceManagerFactory, * receiving the reference through Dependency Injection. This will work without * any Spring API dependencies in the DAO code! * *
It is usually preferable to write your JDO-based DAOs with Spring's * {@link JdoTemplate}, offering benefits such as consistent data access * exceptions instead of JDOExceptions at the DAO layer. However, Spring's * resource and transaction management (and Dependency Injection) will work * for DAOs written against the plain JDO API as well. * *
Of course, you can still access the target PersistenceManagerFactory
* even when your DAOs go through this proxy, by defining a bean reference
* that points directly at your target PersistenceManagerFactory bean.
*
* @author Juergen Hoeller
* @since 1.2
* @see javax.jdo.PersistenceManagerFactory#getPersistenceManager()
* @see javax.jdo.PersistenceManager#close()
* @see PersistenceManagerFactoryUtils#getPersistenceManager
* @see PersistenceManagerFactoryUtils#releasePersistenceManager
*/
public class TransactionAwarePersistenceManagerFactoryProxy implements FactoryBean Default is "true". Can be turned off to enforce access to
* transactional PersistenceManagers, which safely allows for DAOs
* written to get a PersistenceManager without explicit closing
* (i.e. a PersistenceManagerFactory.getPersistenceManager()
* call without corresponding PersistenceManager.close()
call).
* @see PersistenceManagerFactoryUtils#getPersistenceManager(javax.jdo.PersistenceManagerFactory, boolean)
*/
public void setAllowCreate(boolean allowCreate) {
this.allowCreate = allowCreate;
}
/**
* Return whether the PersistenceManagerFactory proxy is allowed to create
* a non-transactional PersistenceManager when no transactional
* PersistenceManager can be found for the current thread.
*/
protected boolean isAllowCreate() {
return this.allowCreate;
}
public PersistenceManagerFactory getObject() {
return this.proxy;
}
public Class extends PersistenceManagerFactory> getObjectType() {
return PersistenceManagerFactory.class;
}
public boolean isSingleton() {
return true;
}
/**
* Invocation handler that delegates getPersistenceManager calls on the
* PersistenceManagerFactory proxy to PersistenceManagerFactoryUtils
* for being aware of thread-bound transactions.
*/
private class PersistenceManagerFactoryInvocationHandler implements InvocationHandler {
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on PersistenceManagerFactory interface coming in...
if (method.getName().equals("equals")) {
// Only consider equal when proxies are identical.
return (proxy == args[0]);
}
else if (method.getName().equals("hashCode")) {
// Use hashCode of PersistenceManagerFactory proxy.
return System.identityHashCode(proxy);
}
else if (method.getName().equals("getPersistenceManager")) {
PersistenceManagerFactory target = getTargetPersistenceManagerFactory();
PersistenceManager pm =
PersistenceManagerFactoryUtils.doGetPersistenceManager(target, isAllowCreate());
Class[] ifcs = ClassUtils.getAllInterfacesForClass(pm.getClass(), pm.getClass().getClassLoader());
return Proxy.newProxyInstance(
pm.getClass().getClassLoader(), ifcs, new PersistenceManagerInvocationHandler(pm, target));
}
// Invoke method on target PersistenceManagerFactory.
try {
return method.invoke(getTargetPersistenceManagerFactory(), args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
/**
* Invocation handler that delegates close calls on PersistenceManagers to
* PersistenceManagerFactoryUtils for being aware of thread-bound transactions.
*/
private static class PersistenceManagerInvocationHandler implements InvocationHandler {
private final PersistenceManager target;
private final PersistenceManagerFactory persistenceManagerFactory;
public PersistenceManagerInvocationHandler(PersistenceManager target, PersistenceManagerFactory pmf) {
this.target = target;
this.persistenceManagerFactory = pmf;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on PersistenceManager interface coming in...
if (method.getName().equals("equals")) {
// Only consider equal when proxies are identical.
return (proxy == args[0]);
}
else if (method.getName().equals("hashCode")) {
// Use hashCode of PersistenceManager proxy.
return System.identityHashCode(proxy);
}
else if (method.getName().equals("close")) {
// Handle close method: only close if not within a transaction.
PersistenceManagerFactoryUtils.doReleasePersistenceManager(
this.target, this.persistenceManagerFactory);
return null;
}
// Invoke method on target PersistenceManager.
try {
return method.invoke(this.target, args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
}