+str #15588,#17229 Java 6 Synchronous File Sink / Source

These are synchronous implementations, because we need to be Java 6
  compatible while developing on 2.3.x. However asynchronous
  implementations using AsynchronousFileChannel will come soon for JDK7
  users.

+ ActorPublisher/Subscriber now manage stopping of the actor
+ added documentation on configuring dispatcher for File IO
+ properly handle if source file does not exist
+ file sink / source come with default io dispatcher
> verified no actors are leaking
> exceptions are caught and onErrored properly
+ moved files to akka.stream.io
+ Added OutputStreamSink and InputStreamSource

akka-stream-tests/src/test/scala/akka/stream/io/OutputStreamSinkSpec.scala

@@ -0,0 +1,66 @@
+/**
+ * Copyright (C) 2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.io
+
+import java.io.OutputStream
+
+import akka.stream.scaladsl.Source
+import akka.stream.testkit.StreamTestKit._
+import akka.stream.testkit.{ AkkaSpec, StreamTestKit }
+import akka.stream.{ ActorFlowMaterializer, ActorFlowMaterializerSettings }
+import akka.testkit.TestProbe
+import akka.util.ByteString
+
+import scala.concurrent.Await
+import scala.concurrent.duration._
+
+class OutputStreamSinkSpec extends AkkaSpec(StreamTestKit.UnboundedMailboxConfig) {
+
+  val settings = ActorFlowMaterializerSettings(system).withDispatcher("akka.actor.default-dispatcher")
+  implicit val materializer = ActorFlowMaterializer(settings)
+
+  "OutputStreamSink" must {
+    "write bytes to void OutputStream" in checkThatAllStagesAreStopped {
+      val p = TestProbe()
+      val datas = List(ByteString("a"), ByteString("c"), ByteString("c"))
+
+      val completion = Source(datas)
+        .runWith(OutputStreamSink(() ⇒ new OutputStream {
+          override def write(i: Int): Unit = ()
+          override def write(bytes: Array[Byte]): Unit = p.ref ! ByteString(bytes).utf8String
+        }))
+
+      p.expectMsg(datas(0).utf8String)
+      p.expectMsg(datas(1).utf8String)
+      p.expectMsg(datas(2).utf8String)
+      Await.ready(completion, 3.seconds)
+    }
+
+    "close underlying stream when error received" in checkThatAllStagesAreStopped {
+      val p = TestProbe()
+      Source.failed(new TE("Boom!"))
+        .runWith(OutputStreamSink(() ⇒ new OutputStream {
+          override def write(i: Int): Unit = ()
+          override def close() = p.ref ! "closed"
+        }))
+
+      p.expectMsg("closed")
+    }
+
+    "close underlying stream when completion received" in checkThatAllStagesAreStopped {
+      val p = TestProbe()
+      Source.empty
+        .runWith(OutputStreamSink(() ⇒ new OutputStream {
+          override def write(i: Int): Unit = ()
+          override def write(bytes: Array[Byte]): Unit = p.ref ! ByteString(bytes).utf8String
+          override def close() = p.ref ! "closed"
+        }))
+
+      p.expectMsg("closed")
+    }
+
+  }
+
+}
+