小编Tom*_*pey的帖子

我正在尝试将基于akka流的流程集成到我的Play 2.5应用程序中.我们的想法是,您可以在照片中流式传输,然后将其作为原始文件,缩略图版本和水印版本写入磁盘.

我设法使用这样的图形来实现这一点:

val byteAccumulator = Flow[ByteString].fold(new ByteStringBuilder())((builder, b) => {builder ++= b.toArray})
                                    .map(_.result().toArray)

def toByteArray = Flow[ByteString].map(b => b.toArray)

val graph = Flow.fromGraph(GraphDSL.create() {implicit builder =>
  import GraphDSL.Implicits._
  val streamFan = builder.add(Broadcast[ByteString](3))
  val byteArrayFan = builder.add(Broadcast[Array[Byte]](2))
  val output = builder.add(Flow[ByteString].map(x => Success(Done)))

  val rawFileSink = FileIO.toFile(file)
  val thumbnailFileSink = FileIO.toFile(getFile(path, Thumbnail))
  val watermarkedFileSink = FileIO.toFile(getFile(path, Watermarked))

  streamFan.out(0) ~> rawFileSink
  streamFan.out(1) ~> byteAccumulator ~> byteArrayFan.in
  streamFan.out(2) ~> output.in

  byteArrayFan.out(0) ~> slowThumbnailProcessing ~> thumbnailFileSink
  byteArrayFan.out(1) ~> slowWatermarkProcessing ~> watermarkedFileSink

  FlowShape(streamFan.in, output.out) …