keygeneratorfactory.java

jGossip是一个简单而功能强大的Java论坛软件（消息板）

/*
 * $Id: KeyGeneratorFactory.java,v 1.2 2004/06/28 01:33:48 alexnet Exp $
 *
 * ***** BEGIN LICENSE BLOCK *****
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and 
 * limitations under the License.
 *
 * The Original Code is JGossip forum code.
 *
 * The Initial Developer of the Original Code is the JResearch, Org. 
 * Portions created by the Initial Developer are Copyright (C) 2004 
 * the Initial Developer. All Rights Reserved. 
 * 
 * Contributor(s): 
 *              Alexey Pavlov <[e-mail]>
 *        
 * ***** END LICENSE BLOCK ***** */
package org.jresearch.gossip.dao.drivers.keygen;

import java.sql.SQLException;
import java.util.ArrayList;

import org.jresearch.gossip.configuration.Configurator;

/**
 * KeyGeneratorFactory holds a list of key generators.
 * 
 * @author <a href="[e-mail]">A. Pavlov</a>
 * @version $version$ $Date: 2004/06/28 01:33:48 $
 */
public class KeyGeneratorFactory 
{
    private KeyGeneratorFactory() {}

    /** 
     * List of <code>SqlInterfaceEntry</code> 
     * holding the instantiated interfaces 
     */
    static ArrayList generators = new ArrayList();

	static Configurator conf = Configurator.getInstance();

    static class KeyGeneratorEntry {
	String name;
	KeyGenerator keyGenerator;
	KeyGeneratorEntry(String name, KeyGenerator keyGenerator) {
		    this.name = name;
		    this.keyGenerator = keyGenerator;
		}
    }

    static interface KeyGeneratorCreator 
    {
		KeyGenerator create();
    }

    /** A list of the available key generators */
    private static KeyGeneratorCreator[] keyGenerators = 
	new KeyGeneratorCreator [] {
	    new KeyGeneratorCreator() {
		    public KeyGenerator create() {
				return new HighLowKeyGenerator();
		    }
		    public String toString() {
				return "highlow";
		    }
		},
	    new KeyGeneratorCreator() {
		    public KeyGenerator create() {
				return new SequenceKeyGenerator();
		    }
		    public String toString() {
				return "sequence";
		    }
		}	
	};


    /**
     * Adds a <code>SqlInterface</code> to the list of 
     * instantiated interfaces.
     *
     * @param the short name of the <code>SqlInterface</code>
     * @return the <code>SqlInterface</code> added to the list
     */
    private static KeyGenerator addKeyGenerator(String name)
 	throws SQLException
    {
	KeyGenerator generator = null;
	for (int i=0; i<keyGenerators.length; i++) {
	    if (name.equals(keyGenerators[i].toString())) {
		generator = keyGenerators[i].create();
		generators.add(new KeyGeneratorEntry
		    (keyGenerators[i].toString(), generator));
		return generator;
	    }
	}
	return null;
    }

    /**
     * Return  an <code>KeyGenerator</code> for the given 
     * class name.
     *
     * @param the short name of the <code>SqlInterface</code>
     * @return a <code>KeyGenerator</code> for the given 
     * class name.
     */
    private static KeyGenerator getKeyGeneratorIntern(String name)
	throws SQLException
    {
	KeyGeneratorEntry entry = null;
	int size = generators.size();
	for (int i=0; i<size; i++) {
	    entry = (KeyGeneratorEntry)generators.get(i);
	    if (entry.name.equals(name))
		return entry.keyGenerator;
	}
	return null;
    }

    /**
     * @param name of the key generator 
     * @return a <code>KeyGenerator</code> indexed by the given name
     */
    public synchronized static KeyGenerator getKeyGenerator(String name)
	throws SQLException
    {
	String low = name.toLowerCase();
	KeyGenerator generator = getKeyGeneratorIntern(low);
	if (generator != null)
	    return generator;

	generator = addKeyGenerator(low);
	if (generator != null)
	    return generator;

	throw new SQLException("mapping.keyGenNotFound", name);

    }

}