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Spring Framework example source code file (IdTransferringMergeEventListener.java)

This example Spring Framework source code file (IdTransferringMergeEventListener.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 - Spring Framework tags/keywords

defaultmergeeventlistener, entitypersister, entitypersister, idtransferringmergeeventlistener, io, map, map, serializable, serializable, sessionimplementor, sessionimplementor, util

The Spring Framework IdTransferringMergeEventListener.java source code

 * Copyright 2002-2007 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.springframework.orm.hibernate3.support;

import java.io.Serializable;
import java.util.Map;

import org.hibernate.engine.SessionImplementor;
import org.hibernate.event.MergeEvent;
import org.hibernate.event.def.DefaultMergeEventListener;
import org.hibernate.persister.entity.EntityPersister;

 * Extension of Hibernate's DefaultMergeEventListener, transferring the ids
 * of newly saved objects to the corresponding original objects (that are part
 * of the detached object graph passed into the <code>merge method).
 * <p>Transferring newly assigned ids to the original graph allows for continuing
 * to use the original object graph, despite merged copies being registered with
 * the current Hibernate Session. This is particularly useful for web applications
 * that might want to store an object graph and then render it in a web view,
 * with links that include the id of certain (potentially newly saved) objects.
 * <p>The merge behavior given by this MergeEventListener is nearly identical
 * to TopLink's merge behavior. See PetClinic for an example, which relies on
 * ids being available for newly saved objects: the <code>HibernateClinic
 * and <code>TopLinkClinic DAO implementations both use straight merge
 * calls, with the Hibernate SessionFactory configuration specifying an
 * <code>IdTransferringMergeEventListener.
 * <p>Typically specified as entry for LocalSessionFactoryBean's "eventListeners"
 * map, with key "merge".
 * @author Juergen Hoeller
 * @since 1.2
 * @see org.springframework.orm.hibernate3.LocalSessionFactoryBean#setEventListeners(java.util.Map)
public class IdTransferringMergeEventListener extends DefaultMergeEventListener {

	 * Hibernate 3.1 implementation of ID transferral.
	protected void entityIsTransient(MergeEvent event, Map copyCache) {
		super.entityIsTransient(event, copyCache);
		SessionImplementor session = event.getSession();
		EntityPersister persister = session.getEntityPersister(event.getEntityName(), event.getEntity());
		// Extract id from merged copy (which is currently registered with Session).
		Serializable id = persister.getIdentifier(event.getResult(), session.getEntityMode());
		// Set id on original object (which remains detached).
		persister.setIdentifier(event.getOriginal(), id, session.getEntityMode());


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