/*
 * Copyright 2002-2018 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.hibernate5.support;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.dao.support.DaoSupport;
import org.springframework.lang.Nullable;
import org.springframework.orm.hibernate5.HibernateTemplate;
import org.springframework.util.Assert;

Convenient super class for Hibernate-based data access objects.
Requires a SessionFactory to be set, providing a HibernateTemplate based on it to subclasses through the getHibernateTemplate() method. Can alternatively be initialized directly with a HibernateTemplate, in order to reuse the latter's settings such as the SessionFactory, exception translator, flush mode, etc. 
This class will create its own HibernateTemplate instance if a SessionFactory is passed in. The "allowCreate" flag on that HibernateTemplate will be "true" by default. A custom HibernateTemplate instance can be used through overriding createHibernateTemplate. 
NOTE: Hibernate access code can also be coded in plain Hibernate style. Hence, for newly started projects, consider adopting the standard Hibernate style of coding data access objects instead, based on SessionFactory.getCurrentSession(). This HibernateTemplate primarily exists as a migration helper for Hibernate 3 based data access code, to benefit from bug fixes in Hibernate 5.x.
Author:
Juergen Hoeller
See Also:
setSessionFactory
getHibernateTemplate
HibernateTemplate
Since:
4.2/**
 * Convenient super class for Hibernate-based data access objects.
 *
 * <p>Requires a {@link SessionFactory} to be set, providing a
 * {@link org.springframework.orm.hibernate5.HibernateTemplate} based on it to
 * subclasses through the {@link #getHibernateTemplate()} method.
 * Can alternatively be initialized directly with a HibernateTemplate,
 * in order to reuse the latter's settings such as the SessionFactory,
 * exception translator, flush mode, etc.
 *
 * <p>This class will create its own HibernateTemplate instance if a SessionFactory
 * is passed in. The "allowCreate" flag on that HibernateTemplate will be "true"
 * by default. A custom HibernateTemplate instance can be used through overriding
 * {@link #createHibernateTemplate}.
 *
 * <p><b>NOTE: Hibernate access code can also be coded in plain Hibernate style.
 * Hence, for newly started projects, consider adopting the standard Hibernate
 * style of coding data access objects instead, based on
 * {@link SessionFactory#getCurrentSession()}.
 * This HibernateTemplate primarily exists as a migration helper for Hibernate 3
 * based data access code, to benefit from bug fixes in Hibernate 5.x.</b>
 *
 * @author Juergen Hoeller
 * @since 4.2
 * @see #setSessionFactory
 * @see #getHibernateTemplate
 * @see org.springframework.orm.hibernate5.HibernateTemplate
 */
public abstract class HibernateDaoSupport extends DaoSupport {

	@Nullable
	private HibernateTemplate hibernateTemplate;


	
Set the Hibernate SessionFactory to be used by this DAO.
Will automatically create a HibernateTemplate for the given SessionFactory.
See Also:
createHibernateTemplate
setHibernateTemplate/**
	 * Set the Hibernate SessionFactory to be used by this DAO.
	 * Will automatically create a HibernateTemplate for the given SessionFactory.
	 * @see #createHibernateTemplate
	 * @see #setHibernateTemplate
	 */
	public final void setSessionFactory(SessionFactory sessionFactory) {
		if (this.hibernateTemplate == null || sessionFactory != this.hibernateTemplate.getSessionFactory()) {
			this.hibernateTemplate = createHibernateTemplate(sessionFactory);
		}
	}

	
Create a HibernateTemplate for the given SessionFactory.
Only invoked if populating the DAO with a SessionFactory reference!
Can be overridden in subclasses to provide a HibernateTemplate instance
with different configuration, or a custom HibernateTemplate subclass.
Params:
sessionFactory – the Hibernate SessionFactory to create a HibernateTemplate for
See Also:
setSessionFactory
Returns:
the new HibernateTemplate instance/**
	 * Create a HibernateTemplate for the given SessionFactory.
	 * Only invoked if populating the DAO with a SessionFactory reference!
	 * <p>Can be overridden in subclasses to provide a HibernateTemplate instance
	 * with different configuration, or a custom HibernateTemplate subclass.
	 * @param sessionFactory the Hibernate SessionFactory to create a HibernateTemplate for
	 * @return the new HibernateTemplate instance
	 * @see #setSessionFactory
	 */
	protected HibernateTemplate createHibernateTemplate(SessionFactory sessionFactory) {
		return new HibernateTemplate(sessionFactory);
	}

	
Return the Hibernate SessionFactory used by this DAO.
/**
	 * Return the Hibernate SessionFactory used by this DAO.
	 */
	@Nullable
	public final SessionFactory getSessionFactory() {
		return (this.hibernateTemplate != null ? this.hibernateTemplate.getSessionFactory() : null);
	}

	
Set the HibernateTemplate for this DAO explicitly,
as an alternative to specifying a SessionFactory.
See Also:
setSessionFactory/**
	 * Set the HibernateTemplate for this DAO explicitly,
	 * as an alternative to specifying a SessionFactory.
	 * @see #setSessionFactory
	 */
	public final void setHibernateTemplate(@Nullable HibernateTemplate hibernateTemplate) {
		this.hibernateTemplate = hibernateTemplate;
	}

	
Return the HibernateTemplate for this DAO,
pre-initialized with the SessionFactory or set explicitly.
Note: The returned HibernateTemplate is a shared instance. You may introspect its configuration, but not modify the configuration (other than from within an DaoSupport.initDao implementation). Consider creating a custom HibernateTemplate instance via new HibernateTemplate(getSessionFactory()), in which case you're allowed to customize the settings on the resulting instance. /**
	 * Return the HibernateTemplate for this DAO,
	 * pre-initialized with the SessionFactory or set explicitly.
	 * <p><b>Note: The returned HibernateTemplate is a shared instance.</b>
	 * You may introspect its configuration, but not modify the configuration
	 * (other than from within an {@link #initDao} implementation).
	 * Consider creating a custom HibernateTemplate instance via
	 * {@code new HibernateTemplate(getSessionFactory())}, in which case
	 * you're allowed to customize the settings on the resulting instance.
	 */
	@Nullable
	public final HibernateTemplate getHibernateTemplate() {
		return this.hibernateTemplate;
	}

	@Override
	protected final void checkDaoConfig() {
		if (this.hibernateTemplate == null) {
			throw new IllegalArgumentException("'sessionFactory' or 'hibernateTemplate' is required");
		}
	}


	
Conveniently obtain the current Hibernate Session.
Throws:
DataAccessResourceFailureException – if the Session couldn't be created
See Also:
SessionFactory.getCurrentSession()
Returns:
the Hibernate Session/**
	 * Conveniently obtain the current Hibernate Session.
	 * @return the Hibernate Session
	 * @throws DataAccessResourceFailureException if the Session couldn't be created
	 * @see SessionFactory#getCurrentSession()
	 */
	protected final Session currentSession() throws DataAccessResourceFailureException {
		SessionFactory sessionFactory = getSessionFactory();
		Assert.state(sessionFactory != null, "No SessionFactory set");
		return sessionFactory.getCurrentSession();
	}

}