001    //$HeadURL: svn+ssh://jwilden@svn.wald.intevation.org/deegree/base/branches/2.5_testing/src/org/deegree/io/datastore/idgenerator/IdGenerator.java $
002    /*----------------------------------------------------------------------------
003     This file is part of deegree, http://deegree.org/
004     Copyright (C) 2001-2009 by:
005       Department of Geography, University of Bonn
006     and
007       lat/lon GmbH
008    
009     This library is free software; you can redistribute it and/or modify it under
010     the terms of the GNU Lesser General Public License as published by the Free
011     Software Foundation; either version 2.1 of the License, or (at your option)
012     any later version.
013     This library is distributed in the hope that it will be useful, but WITHOUT
014     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
015     FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
016     details.
017     You should have received a copy of the GNU Lesser General Public License
018     along with this library; if not, write to the Free Software Foundation, Inc.,
019     59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020    
021     Contact information:
022    
023     lat/lon GmbH
024     Aennchenstr. 19, 53177 Bonn
025     Germany
026     http://lat-lon.de/
027    
028     Department of Geography, University of Bonn
029     Prof. Dr. Klaus Greve
030     Postfach 1147, 53001 Bonn
031     Germany
032     http://www.geographie.uni-bonn.de/deegree/
033    
034     e-mail: info@deegree.org
035    ----------------------------------------------------------------------------*/
036    package org.deegree.io.datastore.idgenerator;
037    
038    import java.lang.reflect.Constructor;
039    import java.lang.reflect.InvocationTargetException;
040    import java.util.Properties;
041    import java.util.ResourceBundle;
042    
043    import org.deegree.io.datastore.DatastoreTransaction;
044    import org.deegree.io.datastore.FeatureId;
045    import org.deegree.io.datastore.schema.MappedFeatureType;
046    
047    /**
048     * Abstract base class for generators that are used to create primary keys (especially {@link FeatureId}s).
049     *
050     * @author <a href="mailto:schneider@lat-lon.de">Markus Schneider </a>
051     * @author last edited by: $Author: mschneider $
052     *
053     * @version $Revision: 18195 $, $Date: 2009-06-18 17:55:39 +0200 (Do, 18 Jun 2009) $
054     */
055    public abstract class IdGenerator {
056    
057        /** Default generator type based on UUIDs. */
058        public static String TYPE_UUID = "UUID";
059    
060        private static final String BUNDLE_NAME = "org.deegree.io.datastore.idgenerator.idgenerator";
061    
062        private static final ResourceBundle RESOURCE_BUNDLE = ResourceBundle.getBundle( BUNDLE_NAME );
063    
064        /** Configuration properties. */
065        protected Properties params;
066    
067        /** {@link MappedFeatureType} that this generator is bound to. */
068        protected MappedFeatureType ft;
069    
070        /**
071         * Creates a new <code>IdGenerator</code> instance.
072         *
073         * @param params
074         *            configuration parameters
075         */
076        protected IdGenerator( Properties params ) {
077            this.params = params;
078        }
079    
080        /**
081         * Returns a new primary key.
082         *
083         * @param ta
084         *            datastore transaction (context)
085         * @return a new primary key.
086         * @throws IdGenerationException
087         *             if the generation of the id could not be performed
088         */
089        public abstract Object getNewId( DatastoreTransaction ta )
090                                throws IdGenerationException;
091    
092        /**
093         * Returns a new id for a feature of the given type.
094         *
095         * @param ft
096         *            feature type
097         * @param ta
098         *            datastore transaction (context)
099         * @return a new feature id.
100         * @throws IdGenerationException
101         */
102        public abstract FeatureId getNewId( MappedFeatureType ft, DatastoreTransaction ta )
103                                throws IdGenerationException;
104    
105        /**
106         * Returns a concrete <code>IdGenerator</code> instance which is identified by the given type code.
107         *
108         * @param type
109         *            type code
110         * @param params
111         *            initialization parameters for the IdGenerator
112         * @return concrete IdGenerator instance
113         */
114        @SuppressWarnings("unchecked")
115        public static final IdGenerator getInstance( String type, Properties params ) {
116            IdGenerator generator = null;
117            String className = null;
118            try {
119                className = RESOURCE_BUNDLE.getString( type );
120                Class<IdGenerator> idGeneratorClass = (Class<IdGenerator>) Class.forName( className );
121    
122                // get constructor
123                Class<?>[] parameterTypes = new Class[] { Properties.class };
124                Constructor<IdGenerator> constructor = idGeneratorClass.getConstructor( parameterTypes );
125    
126                // call constructor
127                Object arglist[] = new Object[] { params };
128                generator = constructor.newInstance( arglist );
129            } catch ( InvocationTargetException e ) {
130                String msg = "Could not instantiate IdGenerator with type '" + type + "': "
131                             + e.getTargetException().getMessage();
132                throw new RuntimeException( msg );
133            } catch ( ClassNotFoundException e ) {
134                String msg = "IdGenerator class '" + className + "' not found: " + e.getMessage();
135                throw new RuntimeException( msg );
136            } catch ( Exception e ) {
137                String msg = "Could not instantiate IdGenerator with type '" + type + "': " + e.getMessage();
138                throw new RuntimeException( msg );
139            }
140            return generator;
141        }
142    }