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.ioc.AnnotationProvider;
024import org.apache.tapestry5.ioc.ObjectCreator;
025import org.apache.tapestry5.ioc.ObjectLocator;
026import org.apache.tapestry5.ioc.ObjectProvider;
027import org.apache.tapestry5.ioc.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        EntityManager proxy = emProxyByName.get(annotation.unitName());
052        if (proxy == null)
053            synchronized (this)
054            {
055                final PlasticProxyFactory proxyFactory = objectLocator.getService(
056                        "PlasticProxyFactory", PlasticProxyFactory.class);
057
058                proxy = proxyFactory.createProxy(EntityManager.class, new ObjectCreator()
059                {
060                    @Override
061                    public Object createObject()
062                    {
063                        final EntityManagerManager entityManagerManager = objectLocator
064                                .getService(EntityManagerManager.class);
065
066                        return JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
067                    }
068                }, "<EntityManagerProxy>");
069                emProxyByName.put(annotation.unitName(), proxy);
070            }
071
072        return proxy;
073    }
074
075}