Scala 您将如何更改此Akka Streams示例以获得物化值Future[ServerBinding]？

第二个例子如下。我添加了

主机

和

端口

的定义

  val host = "localhost"
  val port = 4444
  val connections: Source[IncomingConnection, Future[ServerBinding]] =
    Tcp().bind(host, port)

  connections runForeach { (connection: IncomingConnection) =>
    println(s"New connection from: ${connection.remoteAddress}")

    val echo = Flow[ByteString]
      .via(Framing.delimiter(
        ByteString("\n"),
        maximumFrameLength = 256,
        allowTruncation = true))
      .map(_.utf8String)
      .map(_ + "!!!\n")
      .map(ByteString(_))

    connection.handleWith(echo)
  }

---

您将如何更改该示例，以便还可以掌握

未来的[ServerBinding]

，以便记录成功的绑定并处理绑定错误，例如，端口已在使用中？

您应该能够通过远离

runForeach

的便利性来实现这一点，它隐藏了所涉及的

Sink

的详细信息，而使用显式

Sink

。大概是这样的：

  val host = "localhost"
  val port = 4444
  val connections: Source[IncomingConnection, Future[ServerBinding]] =
    Tcp().bind(host, port)


  val sink = Sink.foreach[IncomingConnection]{ connection =>
    println(s"New connection from: ${connection.remoteAddress}")

    val echo = Flow[ByteString]
      .via(Framing.delimiter(
        ByteString("\n"),
        maximumFrameLength = 256,
        allowTruncation = true))
      .map(_.utf8String)
      .map(_ + "!!!\n")
      .map(ByteString(_))

    connection.handleWith(echo)    
  }

  val serverBinding:Future[ServerBinding] = connections.to(sink).run