注入 Play 类

你经常需要从框架本身（如 WSClient 或 Configuration）访问类的实例。你可以在自己的类中注入它们：

class ComplexService @Inject()(
  configuration: Configuration,
  wsClient: WSClient,
  applicationLifecycle: ApplicationLifecycle,
  cacheApi: CacheApi,
  actorSystem: ActorSystem,
  executionContext: ExecutionContext
  ) {
  // Implementation goes here
  // you can use all the injected classes :
  //
  // configuration to read your .conf files
  // wsClient to make HTTP requests
  // applicationLifecycle to register stuff to do when the app shutdowns
  // cacheApi to use a cache system
  // actorSystem to use AKKA
  // executionContext to work with Futures
}

有些像 ExecutionContext，如果它们被隐式导入，可能会更容易使用。只需将它们添加到构造函数的第二个参数列表中：

class ComplexService @Inject()(
  configuration: Configuration,
  wsClient: WSClient
  )(implicit executionContext: ExecutionContext) {
  // Implementation goes here
  // you can still use the injected classes
  // and executionContext is imported as an implicit argument for the whole class
}