PaginationDao.java 文件源码

/**
 * Creates a new count query for the given {@link Specification}.
 */
private <T> TypedQuery<Long> getCountQuery(final Class<T> entityType, final Specification<T> spec) {

    final CriteriaBuilder builder = em.getCriteriaBuilder();
    final CriteriaQuery<Long> query = builder.createQuery(Long.class);

    final Root<T> root = query.from(entityType);
    applySpecificationToCriteria(root, spec, query);
    query.select(builder.count(root));

    return em.createQuery(query);
}