Play Framework 框架 控制器(Controller)分析和总结.docx

Play Framework 框架的控制器(Controller) Business logic is managed in the domain model layer. As a client (typically a web browser) cannot directly invoke this code, the functionality of a domain object is exposed as resources represented by URIs. 业务逻辑是在域模型层里进行管理，客户端（典型的客户端就是浏览器）无法直接调用业务逻辑代码，客户端是通过资源的 URI 来访问到域对象。 A client uses the uniform API provided by the HTTP protocol to manipulate these resources, and by implication the underlying business logic. However, this mapping of resources to domain objects is not a bijection: the granularity can be expressed at different levels, some resources may be virtuals, for some resources aliases may be defined… 客户端使用 HTTP 协议中提供的统一方法来访问这些特定资源，并隐式调用底 层的业务逻辑。但是这种 URI 资源到域对象之间的映射关系并不是双向的，其粒度可以使用不同的层次来表示。某些资源可以是虚拟的，也可以给资源定义一个别名… This is precisely the role played by the Controller layer: providing a glue between the domain model objects and transport layer events. As the Model layer, controllers are written in pure Java, making it easy to access or modify Model objects. Like the HTTP interface, Controllers are procedural and Request/Response oriented. 这正是控制器层所起的作用：提供一个域模型对象与传输层之间的映射关系。由于域模型层和控制器都是纯 Java 编写的，因此很容易访问或修改模型对象。与 HTTP 接口类似，控制器是面向过程和请求/响应模型的。 The Controller layer reduces the impedance mismatch between HTTP and the Domain Model. 控制器层可减少由于 HTTP 协议和域模型之间不匹配的障碍。 Note 注意 There are different architectural models with different strategies. Some protocols give you direct access to the domain model objects. This is typically what EJB or Corba protocols do. In these cases, the architectural style used is RPC (Remote Procedure Call). These communication styles are hardly compatible with web architecture. 不同的体系架构有着不同的设计策略，某些协议可以让你直接访问域模型对象， 例如 EJB 和 CORBA 协议就是这么做的。在这种情况下，使用的 RPC 远程过 程调用的设计风格，这种设计风格很难跟 Web 应用兼容。 Some technologies like SOAP try to give access to the model object domain through the Web. However, SOAP is just another RPC-style protocol, in this case using HTTP as a transport protocol. It is not an application protocol. 而另外一些技术例如