将服务定义同业务逻辑(控制器)以及数据(实体)访问分离，可确保实体中不会透露任何业务逻辑。

Decoupling the service definition from the business logic (controller) and from access to the data (entity) ensures that no business logic manifests itself in the entities.

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在此基础上，Spring2.5又加入了两个新的注解 —— @Service和@Controller 来完成为通常的三层架构（数据访问对象、服务、web控制器）角色委任。

Spring 2.5 adds two new annotations - @Service and @Controller - to complete the role designations for a common three-tier architecture (data access objects, services, and web controllers).

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控制器将访问其他服务或通过其创建、读取、更新和删除 (CRUD) 操作访问后端实体，从而实现服务业务逻辑。

The controller implements the service business logic by accessing other services or accessing backend entities via their create, read, update and delete (CRUD) operations

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