Question

在玩akka-http实验1.0-M2时，我试图创建一个简单的Hello世界示例。

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?"))
        }
      }
    }
  }
}

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

而失败

另外，如果我改变

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

与

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。要解决这个问题，我需要包含这个：

implicit val executionContext = system.dispatcher

展望akka/http/marshalling/ToResponseMarshallable.scala我看到ToResponseMarshallable.apply需要它返回Future[HttpResponse]。

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

可能是akka团队只需要添加更多@implicitNotFound s。我在direct use of Futures in Akka和spray Marshaller for futures not in implicit scope after upgrading to spray 1.2

找到了不准确但相关的答案

Answer 2

很好找到 - 这个问题仍然存在于Akka HTTP 1.0-RC2中，所以现在的代码必须看起来像这样（给定它们的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

2 个答案: