RevisionBean.java

/**
 * Service facade for entities with revisions
 * 
 * @author Dagvadorj Galbadrakh
 */
@Stateless
public class RevisionBean implements RevisionBeanRemote {

  @EJB
	private EntityBeanRemote entityBean;

	@Override
	public <T extends RevisionModel> void deleteRevision(T entity) {
		entityBean.delete(entity);
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T extends RevisionModel, V extends RevisableModel<T>> T getRevision(
			V entity, Date revisionDate) throws IllegalArgumentException {

		List<T> results = entityBean
				.getEm()
				.createQuery(
						"select r from "
								+ entity.getClass().getSimpleName()
								+ " o join o.revisions r where o=?1 and r.effectiveDate <= ?2 order by r.effectiveDate desc")
				.setParameter(1, entity).setParameter(2, revisionDate)
				.getResultList();

		if (results.isEmpty())
			throw new IllegalArgumentException("No revision this early!");
		else
			return results.get(0);
	}
}