001    /*
002     * JBoss DNA (http://www.jboss.org/dna)
003     * See the COPYRIGHT.txt file distributed with this work for information
004     * regarding copyright ownership.  Some portions may be licensed
005     * to Red Hat, Inc. under one or more contributor license agreements.
006     * See the AUTHORS.txt file in the distribution for a full listing of 
007     * individual contributors. 
008     *
009     * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
010     * is licensed to you under the terms of the GNU Lesser General Public License as
011     * published by the Free Software Foundation; either version 2.1 of
012     * the License, or (at your option) any later version.
013     *
014     * JBoss DNA is distributed in the hope that it will be useful,
015     * but WITHOUT ANY WARRANTY; without even the implied warranty of
016     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
017     * Lesser General Public License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this software; if not, write to the Free
021     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
022     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
023     */
024    package org.jboss.dna.connector.store.jpa.util;
025    
026    import java.util.HashMap;
027    import java.util.Map;
028    import javax.persistence.EntityManager;
029    import net.jcip.annotations.NotThreadSafe;
030    import org.jboss.dna.connector.store.jpa.model.common.NamespaceEntity;
031    
032    /**
033     * @author Randall Hauch
034     */
035    @NotThreadSafe
036    public class Namespaces {
037    
038        private final EntityManager entityManager;
039        private final Map<String, NamespaceEntity> cache = new HashMap<String, NamespaceEntity>();
040    
041        public Namespaces( EntityManager manager ) {
042            this.entityManager = manager;
043        }
044    
045        public NamespaceEntity get( String namespaceUri,
046                                    boolean createIfRequired ) {
047            NamespaceEntity entity = cache.get(namespaceUri);
048            if (entity == null) {
049                entity = NamespaceEntity.findByUri(entityManager, namespaceUri, createIfRequired);
050                if (entity != null) {
051                    cache.put(namespaceUri, entity);
052                }
053            }
054            return entity;
055        }
056    }