at.molindo.esi4j.module.hibernate.HibernateEntityResolver.java Source code

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Here is the source code for at.molindo.esi4j.module.hibernate.HibernateEntityResolver.java

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/**
 * Copyright 2010 Molindo GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package at.molindo.esi4j.module.hibernate;

import java.io.Serializable;
import java.util.Date;
import java.util.Map.Entry;

import org.hibernate.CacheMode;
import org.hibernate.FlushMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.internal.SessionImpl;
import org.hibernate.metadata.ClassMetadata;

import at.molindo.esi4j.chain.Esi4JEntityResolver;
import at.molindo.utils.collections.ClassMap;

public class HibernateEntityResolver implements Esi4JEntityResolver {

    private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(HibernateEntityResolver.class);

    private final SessionFactory _sessionFactory;
    private final ClassMap<String> _entityNames = ClassMap.create();
    private final ThreadLocal<Session> _localSession = new ThreadLocal<Session>();

    public HibernateEntityResolver(SessionFactory sessionFactory) {
        if (sessionFactory == null) {
            throw new NullPointerException("sessionFactory");
        }

        for (Entry<String, ClassMetadata> e : sessionFactory.getAllClassMetadata().entrySet()) {

            Class<?> mappedClass = e.getValue().getMappedClass();

            if (mappedClass != null) {
                _entityNames.put(mappedClass, e.getKey());
            }
        }

        _sessionFactory = sessionFactory;
    }

    /**
     * must be called within originating session
     */
    @Override
    public ObjectKey toObjectKey(Object entity) {
        SessionFactory factory = getSessionFactory();

        Session session = getCurrentSession(factory);

        String entityName = _entityNames.find(entity.getClass());

        ClassMetadata meta = factory.getClassMetadata(entityName);

        Class<?> type = meta.getMappedClass();

        Serializable id = meta.getIdentifier(entity, (SessionImpl) session);
        Long version = toLongVersion(meta.getVersion(entity));

        return new ObjectKey(type, id, version);
    }

    private Long toLongVersion(Object version) {
        if (version instanceof Number) {
            return ((Number) version).longValue();
        } else if (version instanceof Date) {
            return ((Date) version).getTime();
        } else if (version != null) {
            log.warn("unexpected version type " + version.getClass().getName());
        }
        return null;
    }

    /**
     * must be called within originating session
     */
    @Override
    public Object replaceEntity(Object entity) {
        return toObjectKey(entity);
    }

    public void openResolveSession() {
        Session session = _localSession.get();

        if (session != null) {
            log.warn("session already open, now closing first");
            closeResolveSession();
            session = null;
        }

        session = getNewSession(getSessionFactory());
        session.setDefaultReadOnly(true);
        session.setCacheMode(CacheMode.GET);
        session.setFlushMode(FlushMode.MANUAL);
        session.beginTransaction();
        _localSession.set(session);
    }

    public void closeResolveSession() {
        Session session = _localSession.get();
        if (session != null) {
            session.getTransaction().commit();
            session.clear();
            session.close();
            _localSession.set(null);
        } else {
            log.warn("session not open");
        }
    }

    @Override
    public Object resolveEntity(Object replacedEntity) {
        if (replacedEntity instanceof ObjectKey) {
            ObjectKey key = (ObjectKey) replacedEntity;

            Session session = _localSession.get();
            if (session == null) {
                throw new IllegalStateException("no session available");
            }

            // ignore version, use latest, use load for batch fetching
            Object resolvedEntity = session.load(key.getType(), key.getId());

            if (resolvedEntity == null) {
                log.error("can't resolve object " + key);
                return null;
            }

            return resolvedEntity;
        } else {
            // not replaced
            return replacedEntity;
        }

    }

    protected Session getCurrentSession(SessionFactory factory) {
        return factory.getCurrentSession();
    }

    protected Session getNewSession(SessionFactory factory) {
        return factory.openSession();
    }

    public final SessionFactory getSessionFactory() {
        return _sessionFactory;
    }

}