459e74b921
* Operator docs: examples for asSource/FlowWithContext * javafmtAll * Try to capture the essence better * Update index * Include the test use in the snippets
115 lines
4 KiB
Java
115 lines
4 KiB
Java
/*
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* Copyright (C) 2015-2020 Lightbend Inc. <https://www.lightbend.com>
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*/
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package jdocs.stream.operators;
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import akka.actor.ActorSystem;
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// #imports
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import akka.NotUsed;
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import akka.japi.Pair;
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import akka.stream.javadsl.*;
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// #imports
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import akka.testkit.javadsl.TestKit;
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import jdocs.AbstractJavaTest;
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import org.junit.AfterClass;
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import org.junit.BeforeClass;
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import org.junit.Test;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.List;
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import java.util.concurrent.CompletionStage;
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import java.util.concurrent.TimeUnit;
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import static org.hamcrest.CoreMatchers.hasItems;
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import static org.hamcrest.MatcherAssert.assertThat;
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public class WithContextTest extends AbstractJavaTest {
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static ActorSystem system;
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@BeforeClass
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public static void setup() {
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system = ActorSystem.create("WithContextTest");
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}
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@AfterClass
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public static void tearDown() {
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TestKit.shutdownActorSystem(system);
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system = null;
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}
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@Test
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public void documentAsSourceWithContext() throws Exception {
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// #asSourceWithContext
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// values with their contexts as pairs
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Collection<Pair<String, Integer>> values =
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Arrays.asList(Pair.create("eins", 1), Pair.create("zwei", 2), Pair.create("drei", 3));
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// a regular source with pairs as elements
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Source<Pair<String, Integer>, NotUsed> source = Source.from(values);
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// split the pair into stream elements and their context
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SourceWithContext<String, Integer, NotUsed> sourceWithContext =
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source
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.asSourceWithContext(Pair::second) // pick the second pair element as context
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.map(Pair::first); // keep the first pair element as stream element
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SourceWithContext<String, Integer, NotUsed> mapped =
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sourceWithContext
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// regular operators apply to the element without seeing the context
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.map(s -> s.replace('e', 'y'));
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// running the source and asserting the outcome
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CompletionStage<List<Pair<String, Integer>>> result = mapped.runWith(Sink.seq(), system);
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List<Pair<String, Integer>> list = result.toCompletableFuture().get(1, TimeUnit.SECONDS);
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assertThat(
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list, hasItems(Pair.create("yins", 1), Pair.create("zwyi", 2), Pair.create("dryi", 3)));
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// #asSourceWithContext
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}
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@Test
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public void documentAsFlowWithContext() throws Exception {
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// #asFlowWithContext
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// a regular flow with pairs as elements
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Flow<Pair<String, Integer>, Pair<String, Integer>, NotUsed> flow = // ...
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// #asFlowWithContext
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Flow.create();
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// #asFlowWithContext
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// Declare the "flow with context"
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// ingoing: String and Integer
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// outgoing: String and Integer
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FlowWithContext<String, Integer, String, Integer, NotUsed> flowWithContext =
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// convert the flow of pairs into a "flow with context"
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flow.<String, Integer, Integer>asFlowWithContext(
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// at the end of this flow: put the elements and the context back into a pair
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Pair::create,
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// pick the second element of the incoming pair as context
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Pair::second)
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// keep the first pair element as stream element
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.map(Pair::first);
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FlowWithContext<String, Integer, String, Integer, NotUsed> mapped =
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flowWithContext
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// regular operators apply to the element without seeing the context
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.map(s -> s.replace('e', 'y'));
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// running the flow with some sample data and asserting the outcome
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Collection<Pair<String, Integer>> values =
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Arrays.asList(Pair.create("eins", 1), Pair.create("zwei", 2), Pair.create("drei", 3));
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SourceWithContext<String, Integer, NotUsed> source =
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Source.from(values).asSourceWithContext(Pair::second).map(Pair::first);
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CompletionStage<List<Pair<String, Integer>>> result =
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source.via(mapped).runWith(Sink.seq(), system);
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List<Pair<String, Integer>> list = result.toCompletableFuture().get(1, TimeUnit.SECONDS);
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assertThat(
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list, hasItems(Pair.create("yins", 1), Pair.create("zwyi", 2), Pair.create("dryi", 3)));
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// #asFlowWithContext
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}
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}
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