    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}