001: /*
002: * $Header: /export/home/cvsroot/MyPersonalizerRepository/MyPersonalizer/Subsystems/Kernel/Sources/es/udc/mypersonalizer/kernel/model/repository/sql/storers/EntityIdentifierGeneratorSingleton.java,v 1.1.1.1 2004/03/25 12:08:36 fbellas Exp $
003: * $Revision: 1.1.1.1 $
004: * $Date: 2004/03/25 12:08:36 $
005: *
006: * =============================================================================
007: *
008: * Copyright (c) 2003, The MyPersonalizer Development Group
009: * (http://www.tic.udc.es/~fbellas/mypersonalizer/index.html) at
010: * University Of A Coruna
011: * All rights reserved.
012: *
013: * Redistribution and use in source and binary forms, with or without
014: * modification, are permitted provided that the following conditions are met:
015: *
016: * - Redistributions of source code must retain the above copyright notice,
017: * this list of conditions and the following disclaimer.
018: *
019: * - Redistributions in binary form must reproduce the above copyright notice,
020: * this list of conditions and the following disclaimer in the documentation
021: * and/or other materials provided with the distribution.
022: *
023: * - Neither the name of the University Of A Coruna nor the names of its
024: * contributors may be used to endorse or promote products derived from
025: * this software without specific prior written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
028: * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
029: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
030: * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
031: * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
032: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
033: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
034: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
035: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
036: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
037: * POSSIBILITY OF SUCH DAMAGE.
038: *
039: */
040:
041: package es.udc.mypersonalizer.kernel.model.repository.sql.storers;
042:
043: import java.sql.Connection;
044:
045: import es.udc.mypersonalizer.kernel.log.Log;
046: import es.udc.mypersonalizer.kernel.log.LogManager;
047: import es.udc.mypersonalizer.kernel.log.LogNamingConventions;
048: import es.udc.mypersonalizer.kernel.model.repository.sql.config.DatabaseSpecificsConfig;
049: import es.udc.mypersonalizer.kernel.model.repository.sql.config.DatabaseSpecificsConfigManager;
050: import es.udc.mypersonalizer.kernel.util.exceptions.InternalErrorException;
051:
052: /**
053: * This singleton abstract class provides a common interface for generating
054: * identifiers (long integers). The typical use is for getting new
055: * identifiers to be used as keys in entity tables.
056: * <p>
057: * This singleton class creates the concrete singleton on run-time the first
058: * time is needed. The name of such a concrete class is specified by
059: * {@link DatabaseSpecificsConfig}
060: *
061: * @author Fernando Bellas
062: * @author Daniel Fernandez
063: * @since 1.0
064: */
065: public abstract class EntityIdentifierGeneratorSingleton {
066:
067: /**
068: * The singleton instance.
069: */
070: private static EntityIdentifierGeneratorSingleton singleton = null;
071:
072: /*
073: * It uses the standard "MyPersonalizer" configuration mechanism for
074: * getting the name of the concrete singleton class, and creates the
075: * instance.
076: */
077: static {
078:
079: try {
080: DatabaseSpecificsConfig dbSpecifics = DatabaseSpecificsConfigManager
081: .getConfig();
082:
083: String className = dbSpecifics
084: .getIdentifierGeneratorClassName();
085: Class singletonClass = Class.forName(className);
086: singleton = (EntityIdentifierGeneratorSingleton) singletonClass
087: .newInstance();
088: } catch (Exception e) {
089: Log mypersonalizerLog = LogManager
090: .getLog(LogNamingConventions.MYPERSONALIZER);
091: mypersonalizerLog.write(
092: "Could not initialize configuration for "
093: + "EntityIdentifierGeneratorSingleton", e,
094: EntityIdentifierGeneratorSingleton.class);
095: }
096: }
097:
098: /**
099: * Creates an instance of this class
100: */
101: protected EntityIdentifierGeneratorSingleton() {
102: }
103:
104: /**
105: * Retuns the singleton entity identifier generator.
106: *
107: * @return the singleton entity identifier generator
108: */
109: public static EntityIdentifierGeneratorSingleton getInstance() {
110: return singleton;
111: }
112:
113: /**
114: * Generates a new identifier for a given entity table name. The generated
115: * identifier is supposed to be the key of such a table.
116: *
117: * @param connection the connection to the database
118: * @param entityTableName the name of the entity table for which a new
119: * identifier is needed
120: * @return the generated identifier
121: * @throws InternalErrorException if a failure is detected.
122: */
123: public abstract Long nextIdentifier(Connection connection,
124: String entityTableName) throws InternalErrorException;
125:
126: }
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