Hibernate example source code file (TableHiLoGenerator.java)

This example Hibernate source code file (TableHiLoGenerator.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

accesscallback, dialect, integraldatatypeholder, integraldatatypeholder, io, max_lo, object, object, properties, serializable, serializable, sessionimplementor, string, string, tablehilogenerator, util

The Hibernate TableHiLoGenerator.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.id;
import java.io.Serializable;
import java.util.Properties;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.enhanced.AccessCallback;
import org.hibernate.id.enhanced.OptimizerFactory;
import org.hibernate.internal.util.config.ConfigurationHelper;
import org.hibernate.type.Type;

/**
 * <b>hilo

 * <br>
 * An <tt>IdentifierGenerator that returns a Long, constructed using
 * a hi/lo algorithm. The hi value MUST be fetched in a separate transaction
 * to the <tt>Session transaction so the generator must be able to obtain
 * a new connection and commit it. Hence this implementation may not
 * be used  when the user is supplying connections. In this
 * case a <tt>SequenceHiLoGenerator would be a better choice (where
 * supported).<br>
 * <br>
 * Mapping parameters supported: table, column, max_lo
 *
 * @see SequenceHiLoGenerator
 * @author Gavin King
 */
public class TableHiLoGenerator extends TableGenerator {
	/**
	 * The max_lo parameter
	 */
	public static final String MAX_LO = "max_lo";

	private OptimizerFactory.LegacyHiLoAlgorithmOptimizer hiloOptimizer;

	private int maxLo;

	public void configure(Type type, Properties params, Dialect d) {
		super.configure(type, params, d);
		maxLo = ConfigurationHelper.getInt(MAX_LO, params, Short.MAX_VALUE);

		if ( maxLo >= 1 ) {
			hiloOptimizer = new OptimizerFactory.LegacyHiLoAlgorithmOptimizer( type.getReturnedClass(), maxLo );
		}
	}

	public synchronized Serializable generate(final SessionImplementor session, Object obj) {
		// maxLo < 1 indicates a hilo generator with no hilo :?
        if ( maxLo < 1 ) {
			//keep the behavior consistent even for boundary usages
			IntegralDataTypeHolder value = null;
			while ( value == null || value.lt( 0 ) ) {
				value = generateHolder( session );
			}
			return value.makeValue();
		}

		return hiloOptimizer.generate(
				new AccessCallback() {
					public IntegralDataTypeHolder getNextValue() {
						return generateHolder( session );
					}
				}
		);
	}

}