1. 仓储类和仓储接口
https://www.cnblogs.com/caofangsheng/p/5801926.html
2. 泛型仓储类和 工作单元
https://www.cnblogs.com/caofangsheng/p/5804057.html
3. 简单的泛型仓储接口和泛型仓储类
https://www.jianshu.com/p/89b51753b2cf
