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Hibernate example source code file (DefaultDeleteEventListener.java)

This example Hibernate source code file (DefaultDeleteEventListener.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

cachemode, cascade, entityentry, entitypersister, entitypersister, eventsource, eventsource, hibernateexception, io, object, object, persistencecontext, set, set, type, util

The Hibernate DefaultDeleteEventListener.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.event.internal;

import java.io.Serializable;
import java.util.Set;

import org.jboss.logging.Logger;

import org.hibernate.CacheMode;
import org.hibernate.HibernateException;
import org.hibernate.engine.internal.ForeignKeys;
import org.hibernate.engine.internal.Nullability;
import org.hibernate.engine.spi.EntityEntry;
import org.hibernate.event.spi.DeleteEvent;
import org.hibernate.event.spi.DeleteEventListener;
import org.hibernate.event.spi.EventSource;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.LockMode;
import org.hibernate.TransientObjectException;
import org.hibernate.action.internal.EntityDeleteAction;
import org.hibernate.classic.Lifecycle;
import org.hibernate.engine.internal.Cascade;
import org.hibernate.engine.spi.CascadingAction;
import org.hibernate.engine.spi.EntityKey;
import org.hibernate.engine.spi.PersistenceContext;
import org.hibernate.engine.spi.Status;
import org.hibernate.internal.util.collections.IdentitySet;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.type.Type;
import org.hibernate.type.TypeHelper;

/**
 * Defines the default delete event listener used by hibernate for deleting entities
 * from the datastore in response to generated delete events.
 *
 * @author Steve Ebersole
 */
public class DefaultDeleteEventListener implements DeleteEventListener {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class,
                                                                       DefaultDeleteEventListener.class.getName());

	/**
	 * Handle the given delete event.
	 *
	 * @param event The delete event to be handled.
	 *
	 * @throws HibernateException
	 */
	public void onDelete(DeleteEvent event) throws HibernateException {
		onDelete( event, new IdentitySet() );
	}

	/**
	 * Handle the given delete event.  This is the cascaded form.
	 *
	 * @param event The delete event.
	 * @param transientEntities The cache of entities already deleted
	 *
	 * @throws HibernateException
	 */
	public void onDelete(DeleteEvent event, Set transientEntities) throws HibernateException {

		final EventSource source = event.getSession();

		final PersistenceContext persistenceContext = source.getPersistenceContext();
		Object entity = persistenceContext.unproxyAndReassociate( event.getObject() );

		EntityEntry entityEntry = persistenceContext.getEntry( entity );
		final EntityPersister persister;
		final Serializable id;
		final Object version;

		if ( entityEntry == null ) {
            LOG.trace("Entity was not persistent in delete processing");

			persister = source.getEntityPersister( event.getEntityName(), entity );

			if ( ForeignKeys.isTransient( persister.getEntityName(), entity, null, source ) ) {
				deleteTransientEntity( source, entity, event.isCascadeDeleteEnabled(), persister, transientEntities );
				// EARLY EXIT!!!
				return;
			}
            performDetachedEntityDeletionCheck(event);

			id = persister.getIdentifier( entity, source );

			if ( id == null ) {
				throw new TransientObjectException(
						"the detached instance passed to delete() had a null identifier"
				);
			}

			final EntityKey key = source.generateEntityKey( id, persister );

			persistenceContext.checkUniqueness( key, entity );

			new OnUpdateVisitor( source, id, entity ).process( entity, persister );

			version = persister.getVersion( entity );

			entityEntry = persistenceContext.addEntity(
					entity,
					( persister.isMutable() ? Status.MANAGED : Status.READ_ONLY ),
					persister.getPropertyValues( entity ),
					key,
					version,
					LockMode.NONE,
					true,
					persister,
					false,
					false
			);
		}
		else {
            LOG.trace("Deleting a persistent instance");

			if ( entityEntry.getStatus() == Status.DELETED || entityEntry.getStatus() == Status.GONE ) {
                LOG.trace("Object was already deleted");
				return;
			}
			persister = entityEntry.getPersister();
			id = entityEntry.getId();
			version = entityEntry.getVersion();
		}

		/*if ( !persister.isMutable() ) {
			throw new HibernateException(
					"attempted to delete an object of immutable class: " +
					MessageHelper.infoString(persister)
				);
		}*/

		if ( invokeDeleteLifecycle( source, entity, persister ) ) {
			return;
		}

		deleteEntity( source, entity, entityEntry, event.isCascadeDeleteEnabled(), persister, transientEntities );

		if ( source.getFactory().getSettings().isIdentifierRollbackEnabled() ) {
			persister.resetIdentifier( entity, id, version, source );
		}
	}

	/**
	 * Called when we have recognized an attempt to delete a detached entity.
	 * <p/>
	 * This is perfectly valid in Hibernate usage; JPA, however, forbids this.
	 * Thus, this is a hook for HEM to affect this behavior.
	 *
	 * @param event The event.
	 */
	protected void performDetachedEntityDeletionCheck(DeleteEvent event) {
		// ok in normal Hibernate usage to delete a detached entity; JPA however
		// forbids it, thus this is a hook for HEM to affect this behavior
	}

	/**
	 * We encountered a delete request on a transient instance.
	 * <p/>
	 * This is a deviation from historical Hibernate (pre-3.2) behavior to
	 * align with the JPA spec, which states that transient entities can be
	 * passed to remove operation in which case cascades still need to be
	 * performed.
	 *
	 * @param session The session which is the source of the event
	 * @param entity The entity being delete processed
	 * @param cascadeDeleteEnabled Is cascading of deletes enabled
	 * @param persister The entity persister
	 * @param transientEntities A cache of already visited transient entities
	 * (to avoid infinite recursion).
	 */
	protected void deleteTransientEntity(
			EventSource session,
			Object entity,
			boolean cascadeDeleteEnabled,
			EntityPersister persister,
			Set transientEntities) {
        LOG.handlingTransientEntity();
		if ( transientEntities.contains( entity ) ) {
            LOG.trace("Already handled transient entity; skipping");
			return;
		}
		transientEntities.add( entity );
		cascadeBeforeDelete( session, persister, entity, null, transientEntities );
		cascadeAfterDelete( session, persister, entity, transientEntities );
	}

	/**
	 * Perform the entity deletion.  Well, as with most operations, does not
	 * really perform it; just schedules an action/execution with the
	 * {@link org.hibernate.engine.spi.ActionQueue} for execution during flush.
	 *
	 * @param session The originating session
	 * @param entity The entity to delete
	 * @param entityEntry The entity's entry in the {@link PersistenceContext}
	 * @param isCascadeDeleteEnabled Is delete cascading enabled?
	 * @param persister The entity persister.
	 * @param transientEntities A cache of already deleted entities.
	 */
	protected final void deleteEntity(
			final EventSource session,
			final Object entity,
			final EntityEntry entityEntry,
			final boolean isCascadeDeleteEnabled,
			final EntityPersister persister,
			final Set transientEntities) {

        if (LOG.isTraceEnabled()) LOG.trace("Deleting "
                                            + MessageHelper.infoString(persister, entityEntry.getId(), session.getFactory()));

		final PersistenceContext persistenceContext = session.getPersistenceContext();
		final Type[] propTypes = persister.getPropertyTypes();
		final Object version = entityEntry.getVersion();

		final Object[] currentState;
		if ( entityEntry.getLoadedState() == null ) { //ie. the entity came in from update()
			currentState = persister.getPropertyValues( entity );
		}
		else {
			currentState = entityEntry.getLoadedState();
		}

		final Object[] deletedState = createDeletedState( persister, currentState, session );
		entityEntry.setDeletedState( deletedState );

		session.getInterceptor().onDelete(
				entity,
				entityEntry.getId(),
				deletedState,
				persister.getPropertyNames(),
				propTypes
		);

		// before any callbacks, etc, so subdeletions see that this deletion happened first
		persistenceContext.setEntryStatus( entityEntry, Status.DELETED );
		final EntityKey key = session.generateEntityKey( entityEntry.getId(), persister );

		cascadeBeforeDelete( session, persister, entity, entityEntry, transientEntities );

		new ForeignKeys.Nullifier( entity, true, false, session )
				.nullifyTransientReferences( entityEntry.getDeletedState(), propTypes );
		new Nullability( session ).checkNullability( entityEntry.getDeletedState(), persister, true );
		persistenceContext.getNullifiableEntityKeys().add( key );

		// Ensures that containing deletions happen before sub-deletions
		session.getActionQueue().addAction(
				new EntityDeleteAction(
						entityEntry.getId(),
						deletedState,
						version,
						entity,
						persister,
						isCascadeDeleteEnabled,
						session
				)
		);

		cascadeAfterDelete( session, persister, entity, transientEntities );

		// the entry will be removed after the flush, and will no longer
		// override the stale snapshot
		// This is now handled by removeEntity() in EntityDeleteAction
		//persistenceContext.removeDatabaseSnapshot(key);
	}

	private Object[] createDeletedState(EntityPersister persister, Object[] currentState, EventSource session) {
		Type[] propTypes = persister.getPropertyTypes();
		final Object[] deletedState = new Object[propTypes.length];
//		TypeFactory.deepCopy( currentState, propTypes, persister.getPropertyUpdateability(), deletedState, session );
		boolean[] copyability = new boolean[propTypes.length];
		java.util.Arrays.fill( copyability, true );
		TypeHelper.deepCopy( currentState, propTypes, copyability, deletedState, session );
		return deletedState;
	}

	protected boolean invokeDeleteLifecycle(EventSource session, Object entity, EntityPersister persister) {
		if ( persister.implementsLifecycle() ) {
            LOG.debugf("Calling onDelete()");
			if ( ( ( Lifecycle ) entity ).onDelete( session ) ) {
                LOG.debugf("Deletion vetoed by onDelete()");
				return true;
			}
		}
		return false;
	}

	protected void cascadeBeforeDelete(
			EventSource session,
			EntityPersister persister,
			Object entity,
			EntityEntry entityEntry,
			Set transientEntities) throws HibernateException {

		CacheMode cacheMode = session.getCacheMode();
		session.setCacheMode( CacheMode.GET );
		session.getPersistenceContext().incrementCascadeLevel();
		try {
			// cascade-delete to collections BEFORE the collection owner is deleted
			new Cascade( CascadingAction.DELETE, Cascade.AFTER_INSERT_BEFORE_DELETE, session )
					.cascade( persister, entity, transientEntities );
		}
		finally {
			session.getPersistenceContext().decrementCascadeLevel();
			session.setCacheMode( cacheMode );
		}
	}

	protected void cascadeAfterDelete(
			EventSource session,
			EntityPersister persister,
			Object entity,
			Set transientEntities) throws HibernateException {

		CacheMode cacheMode = session.getCacheMode();
		session.setCacheMode( CacheMode.GET );
		session.getPersistenceContext().incrementCascadeLevel();
		try {
			// cascade-delete to many-to-one AFTER the parent was deleted
			new Cascade( CascadingAction.DELETE, Cascade.BEFORE_INSERT_AFTER_DELETE, session )
					.cascade( persister, entity, transientEntities );
		}
		finally {
			session.getPersistenceContext().decrementCascadeLevel();
			session.setCacheMode( cacheMode );
		}
	}
}

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