为什么 DAO 必须是接口或抽象类? [英] Why does a DAO have to be an interface or abstract class?

问题描述

我想了解 RoomDatabase 幕后发生的事情，它要求 DAO 是一个接口或一个抽象类.我已经搜索了很长时间，但所有文章和文档都只解释了方法，而不是原因.

I want to understand what is happening behind the scenes in a RoomDatabase, that it requires the DAO to be either an interface or an abstract class. I've been searching for quite a while, but all articles and documentation only explain the how, not the why.

推荐答案

不只是 Room，Retrofit 和其他库也使用这种模式，它被称为编程接口.而不是仅仅创建一个具体的实现，您只需指定您想要做的事情，他们就会为您提供一个将按照您的要求运行的实现.

It is not just the Room, Retrofit and other libraries use this pattern too, it is called Programming to an Interface. Instead of just creating a concrete implementation you just specify the stuff you want to do and they provide you with an implementation that will behave as you requested.

要进一步学习，您可以查看这篇文章:https://tuhrig.de/programming-to-an-interface/

For further study you can check this article: https://tuhrig.de/programming-to-an-interface/

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