找不到隐含的...：akka.http.server.RoutingSetup

Question

在玩 akka-http experimental 1.0-M2 时，我正在尝试创建一个简单的 Hello world 示例。

import akka.actor.ActorSystem
import akka.http.Http
import akka.http.model.HttpResponse
import akka.http.server.Route
import akka.stream.FlowMaterializer
import akka.http.server.Directives._

object Server extends App {

  val host = "127.0.0.1"
  val port = "8080"

  implicit val system = ActorSystem("my-testing-system")
  implicit val fm = FlowMaterializer()

  val serverBinding = Http(system).bind(interface = host, port = port)
  serverBinding.connections.foreach { connection ⇒
    println("Accepted new connection from: " + connection.remoteAddress)
    connection handleWith Route.handlerFlow {
      path("") {
        get {
          complete(HttpResponse(entity = "Hello world?"))
        }
      }
    }
  }
}

编译失败 could not find implicit value for parameter setup: akka.http.server.RoutingSetup

此外，如果我改变

complete(HttpResponse(entity = "Hello world?"))

和

complete("Hello world?")

我收到另一个错误：type mismatch; found : String("Hello world?") required: akka.http.marshalling.ToResponseMarshallable

Answer 1

通过研究，我能够理解缺少 Execution Context 的问题。为了解决这两个问题，我需要包括这个：

implicit val executionContext = system.dispatcher

查看 akka/http/marshalling/ToResponseMarshallable.scala 我发现 ToResponseMarshallable.apply 需要 returns Future[HttpResponse]。

此外，在akka/http/server/RoutingSetup.scala中，RoutingSetup.apply需要它。

可能是 akka 团队需要再添加一些 @implicitNotFound。我能够在以下位置找到不准确但相关的答案：direct use of Futures in Akka and spray Marshaller for futures not in implicit scope after upgrading to spray 1.2

Answer 2

很好地发现 - Akka HTTP 1.0-RC2 仍然存在这个问题，因此现在的代码必须如下所示（考虑到他们的 API 更改）：

import akka.actor.ActorSystem
import akka.http.scaladsl.server._
import akka.http.scaladsl._
import akka.stream.ActorFlowMaterializer
import akka.stream.scaladsl.{Sink, Source}
import akka.http.scaladsl.model.HttpResponse
import Directives._
import scala.concurrent.Future

object BootWithRouting extends App {

  val host = "127.0.0.1"
  val port = 8080

  implicit val system = ActorSystem("my-testing-system")
  implicit val fm = ActorFlowMaterializer()
  implicit val executionContext = system.dispatcher

  val serverSource: Source[Http.IncomingConnection, Future[Http.ServerBinding]] =
    Http(system).bind(interface = host, port = port)

  serverSource.to(Sink.foreach {
    connection =>
      println("Accepted new connection from: " + connection.remoteAddress)
      connection handleWith Route.handlerFlow {
        path("") {
          get {
            complete(HttpResponse(entity = "Hello world?"))
          }
        }
      }
  }).run()
}

找不到隐含的...：akka.http.server.RoutingSetup

could not find implicit ...: akka.http.server.RoutingSetup

scala

akka

akka-http