Scala Accumulator类代码示例

//设置package包名称以及导入依赖的类
package controllers

import javax.inject._

import play.api.libs.streams.Accumulator
import play.api.mvc.MultipartFormData.FilePart
import play.api.mvc.{Action, Controller, RequestHeader}
import play.core.parsers.Multipart.{FileInfo, FilePartHandler}
import services.MessageDigestService

import scala.concurrent.{ExecutionContext, Future}


@Singleton
class MessageDigestController @Inject()(digestService: MessageDigestService)(implicit exec: ExecutionContext) extends  Controller{


  def index = Action.async {
    Future.successful( Ok(views.html.MessageDigest.index(digestService.algorithms)) )
  }

  def upload = Action(Utility.multipartFormData(digest)){ implicit  request =>
    val digest = request.body.files.map(f => (f.filename, f.ref))
    Ok(views.html.MessageDigest.digest(digest))
  }

  def digest(rh: RequestHeader): FilePartHandler[String] = {
    case FileInfo(key, fileName, contentType) =>
      val Some(Seq(algo, _*)) = rh.queryString.get("algorithm")
      Accumulator(digestService.sink(algo)).map{ d =>
       FilePart(key, fileName, contentType, d)
     }
  }
} 

//设置package包名称以及导入依赖的类
package kamon.play

import akka.util.ByteString
import kamon.trace.Tracer
import kamon.util.SameThreadExecutionContext
import play.api.libs.streams.Accumulator
import play.api.mvc.{ EssentialAction, EssentialFilter, RequestHeader, Result }

class KamonFilter extends EssentialFilter {

  override def apply(next: EssentialAction): EssentialAction = new EssentialAction {
    override def apply(requestHeader: RequestHeader): Accumulator[ByteString, Result] = {

      def onResult(result: Result): Result = {
        Tracer.currentContext.collect { ctx ?
          ctx.finish()
          PlayExtension.httpServerMetrics.recordResponse(ctx.name, result.header.status.toString)
          if (PlayExtension.includeTraceToken) result.withHeaders(PlayExtension.traceTokenHeaderName -> ctx.token)
          else result

        } getOrElse result
      }

      //override the current trace name
      Tracer.currentContext.rename(PlayExtension.generateTraceName(requestHeader))
      val nextAccumulator = next.apply(requestHeader)
      nextAccumulator.map(onResult)(SameThreadExecutionContext)
    }
  }

} 

//设置package包名称以及导入依赖的类
package filters

import javax.inject.Inject

import akka.util.ByteString
import play.api.Logger
import play.api.libs.streams.Accumulator
import play.api.mvc._

import scala.concurrent.ExecutionContext


class LogFilter @Inject()(implicit ec: ExecutionContext) extends EssentialFilter {
  def apply(nextFilter: EssentialAction) = new EssentialAction {
    def apply(requestHeader: RequestHeader) = {

      val startTime = System.currentTimeMillis

      val accumulator: Accumulator[ByteString, Result] = nextFilter(requestHeader)

      accumulator.map { result =>

        val endTime = System.currentTimeMillis
        val requestTime = endTime - startTime
        val requestUri = requestHeader.uri
        val filteredUri = Seq("/javascripts/", "/images/")
        if (filteredUri.exists(uri => uri.containsSlice(requestUri))) {
          Logger.debug(
            s"${requestHeader.method} $requestUri took ${requestTime}ms and returned ${result.header.status}")
        }
        result
      }
    }
  }
} 

//设置package包名称以及导入依赖的类
import akka.stream.Materializer
import akka.stream.scaladsl.Flow
import akka.util.ByteString
import javax.inject._
import play.api._
import play.api.http.HttpFilters
import play.api.libs.streams.Accumulator
import play.api.mvc._
import scala.concurrent.ExecutionContext
import scala.concurrent.Promise


@Singleton
class Filters @Inject() (
  testFilter: TestFilter
) extends HttpFilters {

  override val filters = Seq(testFilter)

}

class TestFilter @Inject() (
  implicit val mat: Materializer,
  implicit val ec: ExecutionContext
) extends EssentialFilter with BodyParsers {
  
  override def apply(nextFilter: EssentialAction) = new EssentialAction {

    lazy val log = play.api.Logger
    
    override def apply(requestHeader: RequestHeader): Accumulator[ByteString, Result] = {
      log.info(">>>> 0. applying TestFilter essential action")
      
      val flowEntered = Promise[Boolean]()
      
      val flow = Flow[ByteString].map { bs =>
        log.info(">>>> 1. passing through flow")
        flowEntered.success(true)
        bs
      }
      
      val accumulator = nextFilter(requestHeader)
      accumulator.through(flow).map { result =>
        val msg = if(flowEntered.isCompleted == false) {
          s"!!!! flow has NOT been feeded !!!!"
        } else {
          "flow has been feeded :)"
        }
        log.info(s"${requestHeader.method} ${requestHeader.path} => $msg (accumulator=$accumulator)")
        result
      }
      
    }
  }

}