Question

我有以下代码，无法编译：

import akka.NotUsed
import akka.actor.typed.Behavior
import akka.actor.typed.scaladsl.Behaviors
import akka.pattern.FutureRef
import akka.stream.scaladsl._
import akka.stream.typed.scaladsl.ActorMaterializer
import org.apache.kafka.clients.admin._
import scala.jdk.FutureConverters._


import scala.concurrent.{ExecutionContext, Future}
import scala.concurrent.duration

object KafkaDetectorActor {

  val create: Behavior[NotUsed] = Behaviors.setup { context =>
    implicit val system = context.system
    implicit val materializer = ActorMaterializer()
    implicit val dispatcher = context.system.dispatchers


    Behaviors.same
  }

  private def health(server: String)(implicit executor: ExecutionContext): Future[Boolean] = {
    val props = new Properties
    props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, server)
    props.put(AdminClientConfig.CONNECTIONS_MAX_IDLE_MS_CONFIG, "10000")
    props.put(AdminClientConfig.REQUEST_TIMEOUT_MS_CONFIG, "5000")

        AdminClient
          .create(props)
          .listTopics()
          .names()
          .asScala

  }

其中names返回KafkaFuture[java.util.Set[String]]。

它无法识别asScala方法。 scala.jdk.FutureConverters._库已导入。我在做什么错了？

Answer 1

{{1}上的scala.jdk.FutureConverters operate，因此请先尝试converting CompletableFuture至KafkaFuture，

CompletableFuture

现在我们可以致电implicit class KafkaFutureToCompletableFuture[T](kafkaFuture: KafkaFuture[T]) { def toCompletableFuture: CompletableFuture[T] = { val wrappingFuture = new CompletableFuture[T] kafkaFuture.whenComplete((value, throwable) => { if (throwable != null) { wrappingFuture.completeExceptionally(throwable) } else { wrappingFuture.complete(value) } }) wrappingFuture } }。例如，

toCompletableFuture.asScala

输出import scala.jdk.FutureConverters._ KafkaFuture.completedFuture(42).toCompletableFuture.asScala.foreach(println)。您可以尝试

为什么不能识别asScala方法？

1 个答案: