如何响应actor调用的结果?

问题描述：

我们正在考虑使用 Akka-HTTP Java API - 使用路由 DSL.

We are looking at using Akka-HTTP Java API - using Routing DSL.

不清楚如何使用路由功能来响应一个HttpRequest；使用无类型 Akka Actor.例如，匹配 Route 路径后，我们如何将请求传递给处理程序"ActorRef，然后以异步方式响应 HttpResponse?

It's not clear how to use the Routing functionality to respond to an HttpRequest; using an Untyped Akka Actor. For example, upon matching a Route path, how do we hand off the request to a "handler" ActorRef, which will then respond with a HttpResponse in a asynchronous way?

Akka-User 邮件列表上发布了一个类似的问题，但没有后续解决方案 - https://groups.google.com/d/msg/akka-user/qHe3Ko7EVvg/KC-aKz_o5aoJ.

A similar question was posted on Akka-User mailing list, but with no followup solutions as such - https://groups.google.com/d/msg/akka-user/qHe3Ko7EVvg/KC-aKz_o5aoJ.

答

这可以通过 onComplete 指令和 ask 模式.

在下面的示例中，RequestHandlerActor 角色用于基于 HttpRequest 创建一个 HttpResponse.从路由内询问此 Actor.

In the below example the RequestHandlerActor actor is used to create a HttpResponse based on the HttpRequest. This Actor is asked from within the route.

我从未使用 Java 来路由代码，所以我的回答是在 Scala 中.

I have never used Java for routing code so my response is in Scala.

import scala.concurrent.duration._
import akka.actor.ActorSystem
import akka.http.scaladsl.model.HttpResponse
import akka.http.scaladsl.model.HttpRequest
import akka.actor.Actor
import akka.http.scaladsl.server.Directives._
import akka.actor.Props
import akka.pattern.ask
import akka.util.Timeout
import scala.util.{Success, Failure}
import akka.http.scaladsl.model.StatusCodes.InternalServerError

class RequestHandlerActor extends Actor {
  override def receive = {
    case httpRequest : HttpRequest =>
      sender() ! HttpResponse(entity = "actor responds nicely")
  }
}

implicit val actorSystem = ActorSystem()
implicit val timeout = Timeout(5 seconds)

val requestRef = actorSystem actorOf Props[RequestHandlerActor]

val route = 
  extractRequest { request =>
    onComplete((requestRef ? request).mapTo[HttpResponse]) {
      case Success(response) => complete(response)
      case Failure(ex) => 
        complete((InternalServerError, s"Actor not playing nice: ${ex.getMessage}"))
    } 
  }

然后可以使用此路由传递到bindAndHandle 方法与任何其他 Flow 一样.

This route can then be used passed into the bindAndHandle method like any other Flow.

如何响应actor调用的结果?

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