001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.internal.jpa;
016
017import java.util.HashMap;
018import java.util.Map;
019
020import javax.persistence.EntityManager;
021import javax.persistence.PersistenceContext;
022
023import org.apache.tapestry5.commons.AnnotationProvider;
024import org.apache.tapestry5.commons.ObjectCreator;
025import org.apache.tapestry5.commons.ObjectLocator;
026import org.apache.tapestry5.commons.ObjectProvider;
027import org.apache.tapestry5.commons.services.PlasticProxyFactory;
028import org.apache.tapestry5.jpa.EntityManagerManager;
029
030public class EntityManagerObjectProvider implements ObjectProvider
031{
032    private Map<String, EntityManager> emProxyByName = new HashMap<String, EntityManager>();
033
034    @Override
035    public <T> T provide(final Class<T> objectType, final AnnotationProvider annotationProvider,
036                         final ObjectLocator locator)
037    {
038        if (objectType.equals(EntityManager.class))
039            return objectType.cast(getOrCreateProxy(annotationProvider, locator));
040
041        return null;
042    }
043
044    @SuppressWarnings(
045    { "unchecked", "rawtypes" })
046    private EntityManager getOrCreateProxy(final AnnotationProvider annotationProvider,
047            final ObjectLocator objectLocator)
048    {
049        final PersistenceContext annotation = annotationProvider
050                .getAnnotation(PersistenceContext.class);
051        final String unitName = annotation == null ? null : annotation.unitName();
052        EntityManager proxy = emProxyByName.get(unitName);
053        if (proxy == null)
054            synchronized (this)
055            {
056                final PlasticProxyFactory proxyFactory = objectLocator.getService(
057                        "PlasticProxyFactory", PlasticProxyFactory.class);
058
059                proxy = proxyFactory.createProxy(EntityManager.class, new ObjectCreator()
060                {
061                    @Override
062                    public Object createObject()
063                    {
064                        final EntityManagerManager entityManagerManager = objectLocator
065                                .getService(EntityManagerManager.class);
066
067                        return JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
068                    }
069                }, "<EntityManagerProxy>");
070                emProxyByName.put(unitName, proxy);
071            }
072
073        return proxy;
074    }
075
076}