使用hibernate的criteria时，应该封装在哪一层？怎么封装

我觉得应该封装在dao层，不然怎么获取session？

demo如下：

public class BaseDaoImpl<E> implements BaseDao<E> {
 
    private Logger log = Logger.getLogger(this.getClass());
 
    @PersistenceContext
    private EntityManager entityManager;
 
    protected Class<?> entityClass;
 
    public BaseDaoImpl(Class<E> entityClass) {
        this.entityClass = Reflections.getClassGenricType(getClass());
    }
 
    /**
     * 获取实体工厂管理对象
     */
    public EntityManager getEntityManager() {
        return entityManager;
    }
 
    /**
     * 获取 Session
     */
    public Session getSession() {
        return (Session) getEntityManager().getDelegate();
    }
 
    /**
     * 使用检索标准对象分页查询
     *
     * @param page
     * @param detachedCriteria
     * @param resultTransformer
     * @return
     */
    @SuppressWarnings("unchecked")
    public Page<E> find(Page<E> page, DetachedCriteria detachedCriteria, ResultTransformer resultTransformer) {
        // get count
        page.setTotalCount(count(detachedCriteria));
        if (page.getTotalCount() < 1) {
            return page;
        }
 
        Criteria criteria = detachedCriteria.getExecutableCriteria(getSession());
        criteria.setResultTransformer(resultTransformer);
        // set page
        // 分页
        if (page.getPageNo() > 0 && page.getPageSize() > 0) {
            criteria.setFirstResult(page.getFirst() - 1);
            criteria.setMaxResults(page.getPageSize());
        }
 
        page.setResult(criteria.list());
        return page;
    }
 
     
 
    /**
     * 使用检索标准对象查询
     *
     * @param detachedCriteria
     * @param resultTransformer
     * @return
     */
    @SuppressWarnings("unchecked")
    public List<E> find(DetachedCriteria detachedCriteria, ResultTransformer resultTransformer) {
        Criteria criteria = detachedCriteria.getExecutableCriteria(getSession());
        criteria.setResultTransformer(resultTransformer);
        return criteria.list();
    }
 
    
 
    /**
     * 创建与会话无关的检索标准对象
     *
     * @param criterions Restrictions.eq("name", value);
     * @return
     */
    public DetachedCriteria createDetachedCriteria(Criterion... criterions) {
        DetachedCriteria dc = DetachedCriteria.forClass(entityClass);
        for (Criterion c : criterions) {
            dc.add(c);
        }
        return dc;
    }
 
    /**
}


所有的daoImpl都继承这个BaseDaoImpl

然后调用的时候在service层直接调用，demo如下：

DetachedCriteria dc = baseDao.createDetachedCriteria();
 
        dc.add(Restrictions.like("name", "%" + name + "%"));
        dc.addOrder(Order.asc("id"));
        //page= baseDao.find(page, dc);
        list = baseDao.find(dc)