RepositoryCRUD.java 文件源码

public default long count() {
    EntityManager entityManager = getEntityManager();
    CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();

    CriteriaQuery criteriaQuery = criteriaBuilder.createQuery();
    Root<E> root = criteriaQuery.from(getEntityClass());
    criteriaQuery.select(criteriaBuilder.count(root));
    TypedQuery<Long> query = entityManager.createQuery(criteriaQuery);

    return query.getSingleResult();
}