/*
 * Copyright 2002-2017 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
 *
 *      https://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.vendor;

import java.lang.reflect.Method;

import javax.persistence.EntityManagerFactory;

import org.hibernate.SessionFactory;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.lang.Nullable;
import org.springframework.orm.jpa.EntityManagerFactoryAccessor;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;

Simple FactoryBean that exposes the underlying SessionFactory behind a Hibernate-backed JPA EntityManagerFactory. 
Primarily available for resolving a SessionFactory by JPA persistence unit name via the "persistenceUnitName" bean property. 
Note that, for straightforward cases, you could also simply declare a factory method:
<bean id="sessionFactory" factory-bean="entityManagerFactory" factory-method="getSessionFactory"/>

And as of JPA 2.1, unwrap.unwrap provides a nice approach as well, in particular within configuration class arrangements: 
@Bean
public SessionFactory sessionFactory(@Qualifier("entityManagerFactory") EntityManagerFactory emf) {
    return emf.unwrap(SessionFactory.class);
}
 Please note: Since Hibernate 5.2 changed its SessionFactory interface to extend JPA's EntityManagerFactory, you may get conflicts when injecting by type, with both the original factory and your custom SessionFactory matching EntityManagerFactory. An explicit qualifier for the original factory (as indicated above) is recommended here. 
Author:
Juergen Hoeller
See Also:
EntityManagerFactoryAccessor.setPersistenceUnitName
setEntityManagerFactory
Since:
3.1
Deprecated:
as of Spring Framework 4.3.12 against Hibernate 5.2, in favor of a custom solution based on unwrap.unwrap with explicit qualifiers and/or primary markers/**
 * Simple {@code FactoryBean} that exposes the underlying {@link SessionFactory}
 * behind a Hibernate-backed JPA {@link EntityManagerFactory}.
 *
 * <p>Primarily available for resolving a SessionFactory by JPA persistence unit name
 * via the {@link #setPersistenceUnitName "persistenceUnitName"} bean property.
 *
 * <p>Note that, for straightforward cases, you could also simply declare a factory method:
 *
 * <pre class="code">
 * &lt;bean id="sessionFactory" factory-bean="entityManagerFactory" factory-method="getSessionFactory"/&gt;
 * </pre>
 *
 * <p>And as of JPA 2.1, {@link EntityManagerFactory#unwrap} provides a nice approach as well,
 * in particular within configuration class arrangements:
 *
 * <pre class="code">
 * &#064;Bean
 * public SessionFactory sessionFactory(@Qualifier("entityManagerFactory") EntityManagerFactory emf) {
 *     return emf.unwrap(SessionFactory.class);
 * }
 * </pre>
 *
 * Please note: Since Hibernate 5.2 changed its {@code SessionFactory} interface to extend JPA's
 * {@code EntityManagerFactory}, you may get conflicts when injecting by type, with both the
 * original factory and your custom {@code SessionFactory} matching {@code EntityManagerFactory}.
 * An explicit qualifier for the original factory (as indicated above) is recommended here.
 *
 * @author Juergen Hoeller
 * @since 3.1
 * @see #setPersistenceUnitName
 * @see #setEntityManagerFactory
 * @deprecated as of Spring Framework 4.3.12 against Hibernate 5.2, in favor of a custom solution
 * based on {@link EntityManagerFactory#unwrap} with explicit qualifiers and/or primary markers
 */
@Deprecated
public class HibernateJpaSessionFactoryBean extends EntityManagerFactoryAccessor implements FactoryBean<SessionFactory> {

	@Override
	@Nullable
	public SessionFactory getObject() {
		EntityManagerFactory emf = getEntityManagerFactory();
		Assert.state(emf != null, "EntityManagerFactory must not be null");
		try {
			Method getSessionFactory = emf.getClass().getMethod("getSessionFactory");
			return (SessionFactory) ReflectionUtils.invokeMethod(getSessionFactory, emf);
		}
		catch (NoSuchMethodException ex) {
			throw new IllegalStateException("No compatible Hibernate EntityManagerFactory found: " + ex);
		}
	}

	@Override
	public Class<?> getObjectType() {
		return SessionFactory.class;
	}

	@Override
	public boolean isSingleton() {
		return true;
	}

}