    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
    015    package org.apache.tapestry5.internal.jpa;
    016
    017    import javax.persistence.EntityManager;
    018    import javax.persistence.PersistenceContext;
    019
    020    import org.apache.tapestry5.ioc.AnnotationProvider;
    021    import org.apache.tapestry5.ioc.ObjectCreator;
    022    import org.apache.tapestry5.ioc.ObjectLocator;
    023    import org.apache.tapestry5.ioc.ObjectProvider;
    024    import org.apache.tapestry5.ioc.services.ClassFactory;
    025    import org.apache.tapestry5.jpa.EntityManagerManager;
    026
    027    public class EntityManagerObjectProvider implements ObjectProvider
    028    {
    029
    030        private EntityManager proxy;
    031
    032        /**
    033         * {@inheritDoc}
    034         */
    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        private synchronized EntityManager getOrCreateProxy(
    045                final AnnotationProvider annotationProvider, final ObjectLocator objectLocator)
    046        {
    047            if (proxy == null)
    048            {
    049                final ClassFactory classFactory = objectLocator.getService("ClassFactory",
    050                        ClassFactory.class);
    051
    052                 final PersistenceContext annotation = annotationProvider
    053                                .getAnnotation(PersistenceContext.class);
    054
    055                proxy = classFactory.createProxy(EntityManager.class, new ObjectCreator()
    056                {
    057                    public Object createObject()
    058                    {
    059                        final EntityManagerManager entityManagerManager = objectLocator
    060                                .getService(EntityManagerManager.class);
    061
    062                        return JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
    063                    }
    064                }, "<EntityManagerProxy>");
    065            }
    066
    067            return proxy;
    068        }
    069
    070    }