/*
* Copyright 2002-2010 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.jpa;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Map;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Query;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.CollectionUtils;
/**
* Factory for a shareable JPA {@link javax.persistence.EntityManager}
* for a given {@link javax.persistence.EntityManagerFactory}.
*
* <p>The shareable EntityManager will behave just like an EntityManager fetched
* from an application server's JNDI environment, as defined by the JPA
* specification. It will delegate all calls to the current transactional
* EntityManager, if any; otherwise it will fall back to a newly created
* EntityManager per operation.
*
* @author Juergen Hoeller
* @author Rod Johnson
* @since 2.0
* @see org.springframework.orm.jpa.LocalEntityManagerFactoryBean
* @see org.springframework.orm.jpa.JpaTransactionManager
*/
public abstract class SharedEntityManagerCreator {
/**
* Create a transactional EntityManager proxy for the given EntityManagerFactory.
* @param emf the EntityManagerFactory to delegate to.
* If this implements the {@link EntityManagerFactoryInfo} interface,
* appropriate handling of the native EntityManagerFactory and available
* {@link EntityManagerPlusOperations} will automatically apply.
* @return a shareable transaction EntityManager proxy
*/
public static EntityManager createSharedEntityManager(EntityManagerFactory emf) {
return createSharedEntityManager(emf, null);
}
/**
* Create a transactional EntityManager proxy for the given EntityManagerFactory.
* @param emf the EntityManagerFactory to delegate to.
* If this implements the {@link EntityManagerFactoryInfo} interface,
* appropriate handling of the native EntityManagerFactory and available
* {@link EntityManagerPlusOperations} will automatically apply.
* @param properties the properties to be passed into the
* <code>createEntityManager</code> call (may be <code>null</code>)
* @return a shareable transaction EntityManager proxy
*/
public static EntityManager createSharedEntityManager(EntityManagerFactory emf, Map properties) {
Class[] emIfcs = null;
if (emf instanceof EntityManagerFactoryInfo) {
EntityManagerFactoryInfo emfInfo = (EntityManagerFactoryInfo) emf;
Class emIfc = emfInfo.getEntityManagerInterface();
if (emIfc == null) {
emIfc = EntityManager.class;
}
JpaDialect jpaDialect = emfInfo.getJpaDialect();
if (jpaDialect != null && jpaDialect.supportsEntityManagerPlusOperations()) {
emIfcs = new Class[] {emIfc, EntityManagerPlus.class};
}
else {
emIfcs = new Class[] {emIfc};
}
}
else {
emIfcs = new Class[] {EntityManager.class};
}
return createSharedEntityManager(emf, properties, emIfcs);
}
/**
* Create a transactional EntityManager proxy for the given EntityManagerFactory.
* @param emf EntityManagerFactory to obtain EntityManagers from as needed
* @param properties the properties to be passed into the
* <code>createEntityManager</code> call (may be <code>null</code>)
* @param entityManagerInterfaces the interfaces to be implemented by the
* EntityManager. Allows the addition or specification of proprietary interfaces.
* @return a shareable transactional EntityManager proxy
*/
public static EntityManager createSharedEntityManager(
EntityManagerFactory emf, Map properties, Class... entityManagerInterfaces) {
ClassLoader cl = null;
if (emf instanceof EntityManagerFactoryInfo) {
cl = ((EntityManagerFactoryInfo) emf).getBeanClassLoader();
}
Class[] ifcs = new Class[entityManagerInterfaces.length + 1];
System.arraycopy(entityManagerInterfaces, 0, ifcs, 0, entityManagerInterfaces.length);
ifcs[entityManagerInterfaces.length] = EntityManagerProxy.class;
return (EntityManager) Proxy.newProxyInstance(
(cl != null ? cl : SharedEntityManagerCreator.class.getClassLoader()),
ifcs, new SharedEntityManagerInvocationHandler(emf, properties));
}
/**
* Invocation handler that delegates all calls to the current
* transactional EntityManager, if any; else, it will fall back
* to a newly created EntityManager per operation.
*/
private static class SharedEntityManagerInvocationHandler implements InvocationHandler {
private final Log logger = LogFactory.getLog(getClass());
private final EntityManagerFactory targetFactory;
private final Map properties;
public SharedEntityManagerInvocationHandler(EntityManagerFactory target, Map properties) {
this.targetFactory = target;
this.properties = properties;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on EntityManager 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 EntityManager proxy.
return hashCode();
}
else if (method.getName().equals("toString")) {
// Deliver toString without touching a target EntityManager.
return "Shared EntityManager proxy for target factory [" + this.targetFactory + "]";
}
else if (method.getName().equals("isOpen")) {
// Handle isOpen method: always return true.
return true;
}
else if (method.getName().equals("close")) {
// Handle close method: suppress, not valid.
return null;
}
else if (method.getName().equals("getTransaction")) {
throw new IllegalStateException(
"Not allowed to create transaction on shared EntityManager - " +
"use Spring transactions or EJB CMT instead");
}
else if (method.getName().equals("joinTransaction")) {
throw new IllegalStateException(
"Not allowed to join transaction on shared EntityManager - " +
"use Spring transactions or EJB CMT instead");
}
// Determine current EntityManager: either the transactional one
// managed by the factory or a temporary one for the given invocation.
EntityManager target =
EntityManagerFactoryUtils.doGetTransactionalEntityManager(this.targetFactory, this.properties);
// Handle EntityManagerProxy interface.
if (method.getName().equals("getTargetEntityManager")) {
if (target == null) {
throw new IllegalStateException("No transactional EntityManager available");
}
return target;
}
// Regular EntityManager operations.
boolean isNewEm = false;
if (target == null) {
logger.debug("Creating new EntityManager for shared EntityManager invocation");
target = (!CollectionUtils.isEmpty(this.properties) ?
this.targetFactory.createEntityManager(this.properties) :
this.targetFactory.createEntityManager());
isNewEm = true;
}
// Invoke method on current EntityManager.
try {
Object result = method.invoke(target, args);
if (isNewEm && result instanceof Query) {
result = Proxy.newProxyInstance(Query.class.getClassLoader(), new Class[] {Query.class},
new DeferredQueryInvocationHandler((Query) result, target));
isNewEm = false;
}
return result;
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
finally {
if (isNewEm) {
EntityManagerFactoryUtils.closeEntityManager(target);
}
}
}
}
/**
* Invocation handler that handles deferred Query objects created by
* non-transactional createQuery invocations on a shared EntityManager.
*/
private static class DeferredQueryInvocationHandler implements InvocationHandler {
private final Query target;
private final EntityManager em;
private DeferredQueryInvocationHandler(Query target, EntityManager em) {
this.target = target;
this.em = em;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// Invocation on Query 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 EntityManager proxy.
return hashCode();
}
// Invoke method on actual Query object.
try {
Object retVal = method.invoke(this.target, args);
return (retVal == this.target ? proxy : retVal);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
finally {
if (method.getName().equals("getResultList") || method.getName().equals("getSingleResult") ||
method.getName().equals("executeUpdate")) {
EntityManagerFactoryUtils.closeEntityManager(this.em);
}
}
}
}
}