GenericFacade.java

package fi.insomnia.bortal.facade;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import fi.insomnia.bortal.model.ModelInterface;

/**
 * Session Bean implementation class GenericFacade
 */
public abstract class GenericFacade<PK,T extends ModelInterface<PK>>{

    private static final Logger logger =LoggerFactory.getLogger(GenericFacade.class);
    
    private Class<T> entClass;
    public GenericFacade(Class<T>entityClass)
    {
        this.entClass = entityClass;
    }
    protected Class<T> getEntityClass()
    {
        return entClass;
    }
    
    protected abstract EntityManager getEm();

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

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

    public T find(PK id) {
        logger.debug("GenericFacade Find class {} By pk {}", new Object[]{getEntityClass(), id});
        T ret = getEm().find(getEntityClass(), id);
        return ret;
    }

    public List<T> findAll() {
        CriteriaQuery<T> cq = getEm().getCriteriaBuilder().createQuery(getEntityClass());
        cq.select(cq.from(getEntityClass()));
        return getEm().createQuery(cq).getResultList();
    }

    public List<T> findRange(int[] range) {
        CriteriaQuery<T> cq = getEm().getCriteriaBuilder().createQuery(getEntityClass());
        cq.select(cq.from(getEntityClass()));
        TypedQuery<T> q = getEm().createQuery(cq);
        q.setMaxResults(range[1] - range[0]);
        q.setFirstResult(range[0]);
        return q.getResultList();
    }

    public long count() {
        CriteriaQuery<Long> cq = getEm().getCriteriaBuilder().createQuery(Long.class);
        Root<T> rt = cq.from(getEntityClass());
        cq.select(getEm().getCriteriaBuilder().count(rt));
        TypedQuery<Long> q = getEm().createQuery(cq);
        return q.getSingleResult();
    }
    
    
    protected T getSingleNullableResult(TypedQuery<T> q) {
        T ret = null;
        try {
            ret = q.getSingleResult();
        } catch (NoResultException e) {
            ret = null;
        }
        return ret;
    }
}