DAO is meaningless now?

最新推荐文章于 2020-08-14 20:32:14 发布

转载最新推荐文章于 2020-08-14 20:32:14 发布 · 551 阅读

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本文探讨了在Spring框架中数据访问对象（DAO）的传统用途及其与业务逻辑的分离。通过对比JPA标准，说明了直接将持久化上下文注入到服务层的方法，这种方法简化了从一种数据访问实现切换到另一种实现的过程。

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The following text comes from Pro Spring 3:

Traditionally, in the data access layer, developers will implement data access objects (DAOs) to separate the data access logic from the business logic. Those DAOs will be injected into the objects within the service layer. The intention is to make the switch from one data access implementation to another easier. However, the DAO pattern introduces one more layer between the service layer and backend database, which has proven to be quite cumbersome in most scenarios. In addition, by using standards like JPA, the persistence context can be injected directly into the service layer for data access, using the standard API as defined by JPA. You then have the flexibility to switch from one JPA persistence provider to another (such as from Hibernate to Eclipselink) easily. As a result, most applications these days do not use DAO, and all the business and data access logic is encapsulated into the service layer.