Hibernate example source code file (VersionValue.java)

This example Hibernate source code file (VersionValue.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

boolean, mappingexception, negative, null, object, object, override, override, string, string, undefined, version, versionvalue, versionvalue

The Hibernate VersionValue.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008-2011, 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.engine.spi;

import org.jboss.logging.Logger;

import org.hibernate.MappingException;
import org.hibernate.id.IdentifierGeneratorHelper;
import org.hibernate.internal.CoreMessageLogger;

/**
 * A strategy for determining if a version value is an version of
 * a new transient instance or a previously persistent transient instance.
 * The strategy is determined by the <tt>unsaved-value attribute in
 * the mapping file.
 *
 * @author Gavin King
 */
public class VersionValue implements UnsavedValueStrategy {

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

	private final Object value;
	/**
	 * Assume the transient instance is newly instantiated if the version
	 * is null, otherwise assume it is a detached instance.
	 */
	public static final VersionValue NULL = new VersionValue() {
		@Override
        public final Boolean isUnsaved(Object version) {
            LOG.trace("Version unsaved-value strategy NULL");
			return version==null;
		}
		@Override
        public Object getDefaultValue(Object currentValue) {
			return null;
		}
		@Override
        public String toString() {
			return "VERSION_SAVE_NULL";
		}
	};
	/**
	 * Assume the transient instance is newly instantiated if the version
	 * is null, otherwise defer to the identifier unsaved-value.
	 */
	public static final VersionValue UNDEFINED = new VersionValue() {
		@Override
        public final Boolean isUnsaved(Object version) {
            LOG.trace("Version unsaved-value strategy UNDEFINED");
			return version==null ? Boolean.TRUE : null;
		}
		@Override
        public Object getDefaultValue(Object currentValue) {
			return currentValue;
		}
		@Override
        public String toString() {
			return "VERSION_UNDEFINED";
		}
	};
	/**
	 * Assume the transient instance is newly instantiated if the version
	 * is negative, otherwise assume it is a detached instance.
	 */
	public static final VersionValue NEGATIVE = new VersionValue() {

		@Override
        public final Boolean isUnsaved(Object version) throws MappingException {
            LOG.trace("Version unsaved-value strategy NEGATIVE");
			if (version==null) return Boolean.TRUE;
            if (version instanceof Number) return ((Number)version).longValue() < 0l;
            throw new MappingException("unsaved-value NEGATIVE may only be used with short, int and long types");
		}
		@Override
        public Object getDefaultValue(Object currentValue) {
			return IdentifierGeneratorHelper.getIntegralDataTypeHolder( currentValue.getClass() )
					.initialize( -1L )
					.makeValue();
		}
		@Override
        public String toString() {
			return "VERSION_NEGATIVE";
		}
	};

	protected VersionValue() {
		this.value = null;
	}

	/**
	 * Assume the transient instance is newly instantiated if
	 * its version is null or equal to <tt>value
	 * @param value value to compare to
	 */
	public VersionValue(Object value) {
		this.value = value;
	}

	@Override
	public Boolean isUnsaved(Object version) throws MappingException  {
        LOG.trace("Version unsaved-value: " + value);
		return version==null || version.equals(value);
	}

	@Override
	public Object getDefaultValue(Object currentValue) {
		return value;
	}

	@Override
    public String toString() {
		return "version unsaved-value: " + value;
	}
}