Akka HTTP路由post实体字符串，与Future一起完成

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.http.scaladsl.server.Directives._
import akka.stream.ActorMaterializer

import scala.concurrent.Future

object Main extends App {
  implicit val system = ActorSystem("my-system")
  implicit val materializer = ActorMaterializer()
  implicit val executionContext = system.dispatcher

  val route =
    path("api" / "post") {
      post {
        entity(as[String]) { entityString =>
          val result: Future[String] = processEntity(entityString)
          onComplete(result) { completed =>
            complete(completed.getOrElse(""))
          }
        }
      }
    }

  def processEntity(entityString: String): Future[String] = {
    // 处理实体字符串的逻辑
    Future.successful("Processed: " + entityString)
  }

  val bindingFuture = Http().bindAndHandle(route, "localhost", 8080)
  println(s"Server online at http://localhost:8080/")

  // 等待服务器停止
  scala.io.StdIn.readLine()
  bindingFuture.flatMap(_.unbind()).onComplete(_ => system.terminate())
}