修改

 /**
     * 更新客户的操作
     *      merge(Object)
     */
    @Test
    public void testUpdate(){
        //1.通过工具类获取entityManager
        EntityManager entityManager = JpaUtils.getEntityManager();
        //2.开启事务
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        //3.增删改查 -- 更新操作
        //i.查询客户
        Customer customer = entityManager.find(Customer.class, 1l);
        //ii.更新客户
        customer.setCustIndustry("线上营销");
        entityManager.merge(customer);
        //4.提交事务
        transaction.commit();
        //5.释放资源
        entityManager.close();
    }