Lagom 开发模式 serviceRegistry

  Lagom 开发模式 serviceRegistry

Dev模式 lagom application 继承的是LagomDevModeServiceLocatorComponents，

该类初始化了一个ServiceRegistry，代码如下

val staticServiceLocator = new ServiceLocator {
    override def doWithService[T](name: String, serviceCall: Call[_, _])(block: (URI) => Future[T])(implicit ec: ExecutionContext): Future[Option[T]] = {
      if (name == ServiceRegistry.ServiceName) {
        block(devModeServiceLocatorUrl).map(Some.apply)
      } else {
        Future.successful(None)
      }
    }
    override def locate(name: String, serviceCall: Call[_, _]): Future[Option[URI]] = {
      if (name == ServiceRegistry.ServiceName) {
        Future.successful(Some(devModeServiceLocatorUrl))
      } else {
        Future.successful(None)
      }
    }
  }

  val serviceClient = new ScaladslServiceClient(wsClient, scaladslWebSocketClient, serviceInfo, staticServiceLocator,
    new ScaladslServiceResolver(new DefaultExceptionSerializer(environment)), None)(executionContext, materializer)

  serviceClient.implement[ServiceRegistry]
}

如上，其中devModeServiceLocatorUrl表示ServiceLocator的地址，可以在application.conf通过lagom.service-locator.url来设置。staticServiceLocator是ServiceLocator的实现，他有两个用处，一个是用来定位serviceCall 的url，另一个是用于实现熔断机制。ScaladslServiceClient继承自ServiceClient，其作用是用于创建service call，具体的创建工作交给了ServiceClientContext完成。

serviceClient.implement[ServiceRegistry]创建了一个ServiceRegistry的微服务客户端，微服务地址由devModeServiceLocatorUrl给出。