查询全部

 /**
     * 查询全部
     *      jqpl：from Customer
     *      sql：SELECT * FROM cst_customer
     */
    @Test
    public void testFindAll(){
        //1.获取entityManager对象
        EntityManager entityManager = JpaUtils.getEntityManager();
        //2.开启事务
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        //3.查询全部
        String jpql = "from Customer";
        Query query = entityManager.createQuery(jpql);
        // 发送查询，封装结果集
        List list = query.getResultList();
        for(Object obj : list){
            System.out.println(obj);
        }
        //4.提交事务
        transaction.commit();
        //5.释放资源
        entityManager.close();
    }