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 org.apache.tapestry5.ioc.AnnotationProvider;
018import org.apache.tapestry5.ioc.ObjectCreator;
019import org.apache.tapestry5.ioc.ObjectLocator;
020import org.apache.tapestry5.ioc.ObjectProvider;
021import org.apache.tapestry5.ioc.services.PlasticProxyFactory;
022import org.apache.tapestry5.jpa.EntityManagerManager;
023
024import javax.persistence.EntityManager;
025import javax.persistence.PersistenceContext;
026
027public class EntityManagerObjectProvider implements ObjectProvider
028{
029
030    private EntityManager proxy;
031
032    @Override
033    public <T> T provide(final Class<T> objectType, final AnnotationProvider annotationProvider,
034                         final ObjectLocator locator)
035    {
036        if (objectType.equals(EntityManager.class))
037            return objectType.cast(getOrCreateProxy(annotationProvider, locator));
038
039        return null;
040    }
041
042    private synchronized EntityManager getOrCreateProxy(
043            final AnnotationProvider annotationProvider, final ObjectLocator objectLocator)
044    {
045        if (proxy == null)
046        {
047            final PlasticProxyFactory proxyFactory = objectLocator.getService("PlasticProxyFactory",
048                    PlasticProxyFactory.class);
049
050            final PersistenceContext annotation = annotationProvider
051                    .getAnnotation(PersistenceContext.class);
052
053            proxy = proxyFactory.createProxy(EntityManager.class, new ObjectCreator()
054            {
055                @Override
056                public Object createObject()
057                {
058                    final EntityManagerManager entityManagerManager = objectLocator
059                            .getService(EntityManagerManager.class);
060
061                    return JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
062                }
063            }, "<EntityManagerProxy>");
064        }
065
066        return proxy;
067    }
068
069}