/* ================================================================

 * Cewolf : Chart enabling Web Objects Framework

 * ================================================================

 *

 * Project Info:  http://cewolf.sourceforge.net

 * Project Lead:  Guido Laures (guido@laures.de);

 *

 * (C) Copyright 2002, by Guido Laures

 *

 * This library is free software; you can redistribute it and/or modify it under the terms

 * of the GNU Lesser General Public License as published by the Free Software Foundation;

 * either version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 */

package de.laures.cewolf.taglib.util;

import java.io.IOException;

import java.io.Serializable;

import java.rmi.MarshalledObject;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

/**

 * @author  Guido Laures

 */

public abstract class KeyGenerator {

    private static final Log log = LogFactory.getLog(KeyGenerator.class);

    private static class NoKeyException extends RuntimeException {

        public NoKeyException(String msg){

            super(msg);

        }

    }

    public static int generateKey(Serializable obj) {

        if (obj == null) {

            NoKeyException ex = new NoKeyException("assertion failed: can not generate key for null,");

            throw ex;

        }

        try {

            MarshalledObject mo = new MarshalledObject(obj);

            return mo.hashCode();

        } catch (IOException ioex) {

            log.error("IOException during key generation KeyGenerator.generateKey()", ioex);

            throw new NoKeyException(obj + " is not serializable.");

        }

    }

}