DAO在Hybris里的定义:

A DAO (Data Access Object) is an interface to the storage back end system. DAOs store and retrieve objects. You use DAOs to save, remove, and find models. DAOs are the place to put SQL or FlexibleSearch statements and nowhere else. This is to ensure further decoupling from the underlying storage facility. DAOs interact with services via models and with the database via FlexibleSearch and SQL statements.

确实这是一个common的concept, 就是对持久层的CRUD进行封装，以实现上一层对持久层具体实现的解耦。