org.sloth.persistence.impl.EntityManagerDao.java Source code

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Here is the source code for org.sloth.persistence.impl.EntityManagerDao.java

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/*
 * Copyright (C) 2009-2010  Stefan Arndt, Christian Autermann, Dustin Demuth,
 *                  Christoph Fendrich, Simon Ottenhues, Christian Paluschek
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.sloth.persistence.impl;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sloth.model.BaseEntity;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

/**
 * Abstract class for Data Acccess Objects using an {@code EntityManager}
 * 
 * @param <T>
 *            a subtype of {@link BaseEntity}F
 * @see EntityManager
 * @author Christian Autermann
 * @author Stefan Arndt
 * @author Dustin Demuth
 * @author Christoph Fendrich
 * @author Simon Ottenhues
 * @author Christian Paluschek
 */
@Transactional
@Repository
public abstract class EntityManagerDao<T extends BaseEntity> {

    /**
     * {@code Logger}-Facade for this class and subclasses.
     */
    protected static final Logger logger = LoggerFactory.getLogger(EntityManagerDao.class);
    private EntityManager entityManager;

    /**
     * Sets the {@code EntityManager} fpr this class. Will be autowired.
     * 
     * @param em
     *            the {@code EntityManager}
     */
    @PersistenceContext(type = PersistenceContextType.EXTENDED)
    public void setEntityManager(EntityManager em) {
        logger.info("Setting EntityManager");
        this.entityManager = em;
    }

    /**
     * Returns the {@code EntityManager}.
     * 
     * @return the {@code EntityManager}
     */
    protected EntityManager getEntityManager() {
        return this.entityManager;
    }

    /**
     * Returns wether the Entity is attached to the {@code EntityManager}.
     * 
     * @param t
     *            the Entity
     * @return {@code true} if it is attached, otherwise {@code false}
     * @throws NullPointerException
     *             if{@code t} is {@code null}
     */
    protected boolean isAttached(T t) throws NullPointerException {
        if (t == null) {
            throw new NullPointerException();
        }
        return getEntityManager().contains(t);
    }
}