将Scala Future转换为Java Future [英] Convert scala future to java future

问题描述

我有一个包含方法的生成的Java接口:

I have a generated java interface containing a method:

public Future<?> getCustomersAsync(AsyncHandler<Customer> asyncHandler);

我想使用Akka来实现它.我写了以下内容:

I want to implement it using Akka. I wrote following:

override def getCustomerAsync(asyncHandler: AsyncHandler[Customer]): Future[_] = {
  myActorRef.ask(GetCustomer, system.actorOf(Props[Responder]))
}

问题在于ask返回scala.concurrent.Future[Any]，并且该方法必须返回java.util.concurrent.Future[?]:

The issue is that ask returns scala.concurrent.Future[Any] and the method must return java.util.concurrent.Future[?]:

Error:(33, 17) type mismatch;
 found   : scala.concurrent.Future[Any]
 required: java.util.concurrent.Future[?]
    myActorRef.ask(GetCustomer, system.actorOf(Props[Responder]))
                  ^

我该如何进行转换?

推荐答案

将它们转换是不切实际的，因为scala Future不提供中断功能或其他任何取消机制.因此，没有直接的充分证明方式可以通过中断或通过Future中的方法调用来取消未来.

Well its not practical to convert them, because scala Future do not provide functionality to interrupt or any other mechanism for cancellation. So there is no direct full-proof way to cancel a future via interruption or otherwise via method call in Future.

因此，最简单的解决方案是:如果不需要取消，则为:

So the simplest solution can be if cancellation is not desired would be:

  def convert[T](x:Future[T]):java.util.concurrent.Future[T]={
    new concurrent.Future[T] {
      override def isCancelled: Boolean = throw new UnsupportedOperationException

      override def get(): T = Await.result(x, Duration.Inf)

      override def get(timeout: Long, unit: TimeUnit): T = Await.result(x, Duration.create(timeout, unit))

      override def cancel(mayInterruptIfRunning: Boolean): Boolean = throw new UnsupportedOperationException

      override def isDone: Boolean = x.isCompleted
    }
  }

但是如果您仍然需要cancel，则有缺陷的修补程序将显示为

But in case if you still need cancel, a handicapped fix would be as shown

此处.但是我不推荐它，因为它摇摇欲坠

here. But I wouldn't recommend it though as its shaky

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