Hibernate example source code file (AbstractUUIDGenerator.java)

This example Hibernate source code file (AbstractUUIDGenerator.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

abstractuuidgenerator, abstractuuidgenerator, exception, exception, identifiergenerator, ip, ip, jvm, jvm, net, network

The Hibernate AbstractUUIDGenerator.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC 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 Middleware LLC.
 *
 * 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.net.InetAddress;
import org.hibernate.internal.util.BytesHelper;

/**
 * The base class for identifier generators that use a UUID algorithm. This
 * class implements the algorithm, subclasses define the identifier
 * format.
 *
 * @see UUIDHexGenerator
 * @author Gavin King
 */

public abstract class AbstractUUIDGenerator implements IdentifierGenerator {

	private static final int IP;
	static {
		int ipadd;
		try {
			ipadd = BytesHelper.toInt( InetAddress.getLocalHost().getAddress() );
		}
		catch (Exception e) {
			ipadd = 0;
		}
		IP = ipadd;
	}
	private static short counter = (short) 0;
	private static final int JVM = (int) ( System.currentTimeMillis() >>> 8 );

	public AbstractUUIDGenerator() {
	}

	/**
	 * Unique across JVMs on this machine (unless they load this class
	 * in the same quater second - very unlikely)
	 */
	protected int getJVM() {
		return JVM;
	}

	/**
	 * Unique in a millisecond for this JVM instance (unless there
	 * are > Short.MAX_VALUE instances created in a millisecond)
	 */
	protected short getCount() {
		synchronized(AbstractUUIDGenerator.class) {
			if (counter<0) counter=0;
			return counter++;
		}
	}

	/**
	 * Unique in a local network
	 */
	protected int getIP() {
		return IP;
	}

	/**
	 * Unique down to millisecond
	 */
	protected short getHiTime() {
		return (short) ( System.currentTimeMillis() >>> 32 );
	}
	protected int getLoTime() {
		return (int) System.currentTimeMillis();
	}


}