Hibernate example source code file (EnversIllustrationTest.java)

This example Hibernate source code file (EnversIllustrationTest.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

a, a, auditreader, date, date, entitymanagerfactory, enversillustrationtest, event, event, exception, exception, our, override, testcase, util

The Hibernate EnversIllustrationTest.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.tutorial.envers;

import java.util.Date;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import junit.framework.TestCase;

import org.hibernate.envers.AuditReader;
import org.hibernate.envers.AuditReaderFactory;

/**
 * Illustrates the set up and use of Envers.
 * <p>
 * This example is different from the others in that we really need to save multiple revisions to the entity in
 * order to get a good look at Envers in action.
 *
 * @author Steve Ebersole
 */
public class EnversIllustrationTest extends TestCase {
	private EntityManagerFactory entityManagerFactory;

	@Override
	protected void setUp() throws Exception {
		// like discussed with regards to SessionFactory, an EntityManagerFactory is set up once for an application
		// 		IMPORTANT: notice how the name here matches the name we gave the persistence-unit in persistence.xml!
		entityManagerFactory = Persistence.createEntityManagerFactory( "org.hibernate.tutorial.envers" );
	}

	@Override
	protected void tearDown() throws Exception {
		entityManagerFactory.close();
	}

	public void testBasicUsage() {
		// create a couple of events
		EntityManager entityManager = entityManagerFactory.createEntityManager();
		entityManager.getTransaction().begin();
		entityManager.persist( new Event( "Our very first event!", new Date() ) );
		entityManager.persist( new Event( "A follow up event", new Date() ) );
		entityManager.getTransaction().commit();
		entityManager.close();

		// now lets pull events from the database and list them
		entityManager = entityManagerFactory.createEntityManager();
		entityManager.getTransaction().begin();
        List<Event> result = entityManager.createQuery( "from Event", Event.class ).getResultList();
		for ( Event event : result ) {
			System.out.println( "Event (" + event.getDate() + ") : " + event.getTitle() );
		}
        entityManager.getTransaction().commit();
        entityManager.close();

		// so far the code is the same as we have seen in previous tutorials.  Now lets leverage Envers...

		// first lets create some revisions
		entityManager = entityManagerFactory.createEntityManager();
		entityManager.getTransaction().begin();
		Event myEvent = entityManager.find( Event.class, 2L ); // we are using the increment generator, so we know 2 is a valid id
		myEvent.setDate( new Date() );
		myEvent.setTitle( myEvent.getTitle() + " (rescheduled)" );
        entityManager.getTransaction().commit();
        entityManager.close();

		// and then use an AuditReader to look back through history
		entityManager = entityManagerFactory.createEntityManager();
		entityManager.getTransaction().begin();
		myEvent = entityManager.find( Event.class, 2L );
		assertEquals( "A follow up event (rescheduled)", myEvent.getTitle() );
		AuditReader reader = AuditReaderFactory.get( entityManager );
		Event firstRevision = reader.find( Event.class, 2L, 1 );
		assertFalse( firstRevision.getTitle().equals( myEvent.getTitle() ) );
		assertFalse( firstRevision.getDate().equals( myEvent.getDate() ) );
		Event secondRevision = reader.find( Event.class, 2L, 2 );
		assertTrue( secondRevision.getTitle().equals( myEvent.getTitle() ) );
		assertTrue( secondRevision.getDate().equals( myEvent.getDate() ) );
		entityManager.getTransaction().commit();
        entityManager.close();
	}
}