AbstractFacade.java

/*
 *  The MIT License
 * 
 *  Copyright 2011 Michaël Schwartz <m.schwartz@epokmedia.fr>.
 * 
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 * 
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 * 
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *  THE SOFTWARE.
 */

package miage.ecom.session;

import java.util.List;
import javax.persistence.EntityManager;

/**
 *
 * @author Schwartz Michaël <m.schwartz@epokmedia.fr>
 */
public abstract class AbstractFacade<T> {
	private Class<T> entityClass;

	public AbstractFacade(Class<T> entityClass) {
		this.entityClass = entityClass;
	}

	protected abstract EntityManager getEntityManager();

	public void create(T entity) {
		getEntityManager().persist(entity);
	}

	public void edit(T entity) {
		getEntityManager().merge(entity);
	}

	public void remove(T entity) {
		getEntityManager().remove(getEntityManager().merge(entity));
	}

	public T find(Object id) {
		return getEntityManager().find(entityClass, id);
	}

	public List<T> findAll() {
		javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
		cq.select(cq.from(entityClass));
		return getEntityManager().createQuery(cq).getResultList();
	}

	public List<T> findRange(int[] range) {
		javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
		cq.select(cq.from(entityClass));
		javax.persistence.Query q = getEntityManager().createQuery(cq);
		q.setMaxResults(range[1] - range[0]);
		q.setFirstResult(range[0]);
		return q.getResultList();
	}

	public int count() {
		javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
		javax.persistence.criteria.Root<T> rt = cq.from(entityClass);
		cq.select(getEntityManager().getCriteriaBuilder().count(rt));
		javax.persistence.Query q = getEntityManager().createQuery(cq);
		return ((Long) q.getSingleResult()).intValue();
	}

}