DataBaseTest.java 文件源码

private int numberCitizen(){
    EntityManager em = Jpa.createEntityManager();
    EntityTransaction trx = em.getTransaction();
    trx.begin();
    try{

        Query query = Jpa.getManager().createQuery("select c from CitizenDB c");
        return query.getResultList().size();

    }catch(RuntimeException e){
        trx.rollback();
        throw e;
    }
    finally{
        em.close();
    }
}