+doc #19429 initial merge of docs-dev and docs

akka-docs/rst/java/code/docs/stream/javadsl/cookbook/RecipeDigest.java

@@ -0,0 +1,105 @@
+/**
+ *  Copyright (C) 2015 Typesafe <http://typesafe.com/>
+ */
+package docs.stream.javadsl.cookbook;
+
+import akka.actor.ActorSystem;
+import akka.stream.ActorMaterializer;
+import akka.stream.Materializer;
+import akka.stream.javadsl.Sink;
+import akka.stream.javadsl.Source;
+import akka.stream.stage.Context;
+import akka.stream.stage.PushPullStage;
+import akka.stream.stage.SyncDirective;
+import akka.stream.stage.TerminationDirective;
+import akka.testkit.JavaTestKit;
+import akka.util.ByteString;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import scala.concurrent.Await;
+import scala.concurrent.duration.Duration;
+import scala.runtime.BoxedUnit;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+
+public class RecipeDigest extends RecipeTest {
+  static ActorSystem system;
+
+  @BeforeClass
+  public static void setup() {
+    system = ActorSystem.create("RecipeDigest");
+  }
+
+  @AfterClass
+  public static void tearDown() {
+    JavaTestKit.shutdownActorSystem(system);
+    system = null;
+  }
+
+  final Materializer mat = ActorMaterializer.create(system);
+
+  @Test
+  public void work() throws Exception {
+    new JavaTestKit(system) {
+      //#calculating-digest
+      public PushPullStage<ByteString, ByteString> digestCalculator(String algorithm)
+          throws NoSuchAlgorithmException {
+        return new PushPullStage<ByteString, ByteString>() {
+          final MessageDigest digest = MessageDigest.getInstance(algorithm);
+
+          @Override
+          public SyncDirective onPush(ByteString chunk, Context<ByteString> ctx) {
+            digest.update(chunk.toArray());
+            return ctx.pull();
+          }
+
+          @Override
+          public SyncDirective onPull(Context<ByteString> ctx) {
+            if (ctx.isFinishing()) {
+              return ctx.pushAndFinish(ByteString.fromArray(digest.digest()));
+            } else {
+              return ctx.pull();
+            }
+          }
+
+          @Override
+          public TerminationDirective onUpstreamFinish(Context<ByteString> ctx) {
+            // If the stream is finished, we need to emit the last element in the onPull block.
+            // It is not allowed to directly emit elements from a termination block
+            // (onUpstreamFinish or onUpstreamFailure)
+            return ctx.absorbTermination();
+          }
+        };
+      }
+      //#calculating-digest
+
+      {
+        Source<ByteString, BoxedUnit> data = Source.from(Arrays.asList(
+          ByteString.fromString("abcdbcdecdef"),
+          ByteString.fromString("defgefghfghighijhijkijkljklmklmnlmnomnopnopq")));
+
+        //#calculating-digest2
+        final Source<ByteString, BoxedUnit> digest = data
+          .transform(() -> digestCalculator("SHA-256"));
+        //#calculating-digest2
+
+        ByteString got = Await.result(digest.runWith(Sink.head(), mat), Duration.create(3, TimeUnit.SECONDS));
+        assertEquals(ByteString.fromInts(
+          0x24, 0x8d, 0x6a, 0x61,
+          0xd2, 0x06, 0x38, 0xb8,
+          0xe5, 0xc0, 0x26, 0x93,
+          0x0c, 0x3e, 0x60, 0x39,
+          0xa3, 0x3c, 0xe4, 0x59,
+          0x64, 0xff, 0x21, 0x67,
+          0xf6, 0xec, 0xed, 0xd4,
+          0x19, 0xdb, 0x06, 0xc1), got);
+      }
+    };
+  }
+}