DAO和Data Mapper有什么区别？ [英] What's the difference between DAO and Data Mapper

问题描述

DAO模式和数据映射模式之间有区别吗？ DAO只是数据映射器之一吗？

Is there a difference between the DAO pattern and the Data Mapper pattern? Is DAO just one of doing Data Mapper?

推荐答案

我实际上不会调用DAO模式。正如我看到的那样，DAO几乎是一个数据访问对象，它封装了访问持久数据存储的细节，一般来说与数据库无关：

I wouldn't actually call DAO a "pattern". As I see it, DAO is pretty much what it is -- a Data Access Object", which encapsulates the details of accessing a persistent data store and generally speaking has nothing to do with the database:

interface IBlogDaoService
{
    Blog GetBlog(long id);
    void SaveBlog(Blog blog);
}

很明显，实现可以使用任何一个DB（在这种情况下，使用数据映射器是合乎逻辑的）或简单的XML文件存储机制。

It's clear that implementations can use either DB (in which case it's quite logical to use a Data Mapper), or simple XML file storage mechanism.

另一方面，数据映射器更多的是一种模式，它定义了一个层，负责将对象的内存中图形转换为关系结构。

The Data Mapper on the other hand is more of a pattern, which defines a layer responsible for translating in-memory graphs of objects to the relational structure.

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