Merge pull request #15054 from akka/wip-13890-akka-java8-template-master-ban

(Forward Port) +sam #13890 Add Akka Main Activator template for Java 8

akka-samples/akka-sample-main-java-lambda/COPYING

@@ -0,0 +1,121 @@
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akka-samples/akka-sample-main-java-lambda/LICENSE

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+Activator Template by Typesafe
+
+Licensed under Public Domain (CC0)
+
+To the extent possible under law, the person who associated CC0 with
+this Activator Tempate has waived all copyright and related or neighboring
+rights to this Activator Template.
+
+You should have received a copy of the CC0 legalcode along with this
+work.  If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

akka-samples/akka-sample-main-java-lambda/activator.properties

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+name=akka-sample-main-java-lambda
+title=Akka Main in Java with Lambdas
+description=Actor based version of obligatory Hello World program using the generic launcher class akka.Main.
+tags=Basics,akka,java,java8,starter
+authorName=Akka Team
+authorLink=http://akka.io/
+sourceLink=https://github.com/akka/akka

akka-samples/akka-sample-main-java-lambda/build.sbt

@@ -0,0 +1,10 @@
+name := "akka-sample-main-java-lambda"
+
+version := "1.0"
+
+scalaVersion := "2.10.3"
+
+libraryDependencies ++= Seq(
+  "com.typesafe.akka" %% "akka-actor" % "2.4-SNAPSHOT"
+)
+

akka-samples/akka-sample-main-java-lambda/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>akka-sample-main-java-lambda</artifactId>
+  <groupId>com.typesafe.akka.samples</groupId>
+  <name>Akka Main in Java</name>
+  <version>1.0</version>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>com.typesafe.akka</groupId>
+      <artifactId>akka-actor_2.10</artifactId>
+      <version>2.4-SNAPSHOT</version>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.1</version>
+        <configuration>
+          <source>1.8</source>
+          <target>1.8</target>
+          <fork>true</fork>
+          <compilerArgs>
+            <arg>-Xlint</arg>
+          </compilerArgs>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

akka-samples/akka-sample-main-java-lambda/project/build.properties

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+sbt.version=0.13.1

akka-samples/akka-sample-main-java-lambda/src/main/java/sample/hello/Greeter.java

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+package sample.hello;
+
+import akka.actor.AbstractActor;
+import akka.japi.pf.ReceiveBuilder;
+
+public class Greeter extends AbstractActor {
+
+  public static enum Msg {
+    GREET, DONE;
+  }
+
+  public Greeter() {
+    receive(ReceiveBuilder.
+      matchEquals(Msg.GREET, m -> {
+        System.out.println("Hello World!");
+        sender().tell(Msg.DONE, self());
+      }).build());
+  }
+}

akka-samples/akka-sample-main-java-lambda/src/main/java/sample/hello/HelloWorld.java

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+package sample.hello;
+
+import akka.actor.AbstractActor;
+import akka.actor.Props;
+import akka.actor.ActorRef;
+import akka.japi.pf.ReceiveBuilder;
+import static sample.hello.Greeter.Msg;
+
+public class HelloWorld extends AbstractActor {
+
+  public HelloWorld() {
+    receive(ReceiveBuilder.
+      matchEquals(Msg.DONE, m -> {
+        // when the greeter is done, stop this actor and with it the application
+        context().stop(self());
+      }).build());
+  }
+
+  @Override
+  public void preStart() {
+    // create the greeter actor
+    final ActorRef greeter = getContext().actorOf(Props.create(Greeter.class), "greeter");
+    // tell it to perform the greeting
+    greeter.tell(Greeter.Msg.GREET, self());
+  }
+}

akka-samples/akka-sample-main-java-lambda/src/main/java/sample/hello/Main.java

@@ -0,0 +1,8 @@
+package sample.hello;
+
+public class Main {
+
+  public static void main(String[] args) {
+    akka.Main.main(new String[] { HelloWorld.class.getName() });
+  }
+}

akka-samples/akka-sample-main-java-lambda/src/main/java/sample/hello/Main2.java

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+package sample.hello;
+
+import akka.actor.*;
+import akka.japi.pf.ReceiveBuilder;
+
+public class Main2 {
+
+  public static void main(String[] args) {
+    ActorSystem system = ActorSystem.create("Hello");
+    ActorRef a = system.actorOf(Props.create(HelloWorld.class), "helloWorld");
+    system.actorOf(Props.create(Terminator.class, a), "terminator");
+  }
+
+  public static class Terminator extends AbstractLoggingActor {
+
+    private final ActorRef ref;
+
+    public Terminator(ActorRef ref) {
+      this.ref = ref;
+      getContext().watch(ref);
+      receive(ReceiveBuilder.
+        match(Terminated.class, t -> {
+          log().info("{} has terminated, shutting down system", ref.path());
+          context().system().shutdown();
+        }).build());
+    }
+  }
+}

akka-samples/akka-sample-main-java-lambda/src/main/resources/application.conf

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+akka {
+  loglevel = INFO
+}

akka-samples/akka-sample-main-java-lambda/tutorial/index.html

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+<!-- <html> -->
+<head>
+    <title>The Obligatory Hello World</title>
+</head>
+
+<body>
+
+<div>
+<h2>The Obligatory Hello World</h2>
+
+<p>
+Since every programming paradigm needs to solve the tough problem of printing a
+well-known greeting to the console we’ll introduce you to the actor-based
+version.
+</p>
+
+<p>
+Open <a href="#code/src/main/java/sample/hello/HelloWorld.java" class="shortcut">HelloWorld.java</a>
+</p>
+
+<p>
+The <code>HelloWorld</code> actor is the application’s “main” class; when it terminates
+the application will shut down—more on that later. The main business logic
+happens in the <code>preStart</code> method, where a <code>Greeter</code> actor is created
+and instructed to issue that greeting we crave for. When the greeter is done it
+will tell us so by sending back a message, and when that message has been
+received it will be passed into the behavior described by the <code>receive</code>
+method where we can conclude the demonstration by stopping the <code>HelloWorld</code>
+actor.
+</p>
+
+</div>
+<div>
+
+<h2>The Greeter</h2>
+
+<p>
+You will be very curious to see how the <code>Greeter</code> actor performs the
+actual task. Open <a href="#code/src/main/java/sample/hello/Greeter.java" class="shortcut">Greeter.java</a>.
+</p>
+
+<p>
+
+This is extremely simple now: after its creation this actor will not do
+anything until someone sends it a message, and if that happens to be an
+invitation to greet the world then the <code>Greeter</code> complies and informs the
+requester that the deed has been done.
+</p>
+
+</div>
+<div>
+
+<h2>Main class</h2>
+
+<p>
+Go to the <a href="#run" class="shortcut">Run</a> tab, and start the application main class
+<code>sample.hello.Main</code>. In the log output you can see the "Hello World!" greeting.
+</p>
+
+<p>
+<a href="#code/src/main/java/sample/hello/Main.java" class="shortcut">Main.java</a>
+is actually just a small wrapper around the generic launcher class <code>akka.Main</code>,
+which expects only one argument: the class name of the application’s main actor. This main
+method will then create the infrastructure needed for running the actors, start the
+given main actor and arrange for the whole application to shut down once the
+main actor terminates. Thus you will be able to run the application with a
+command similar to the following:
+</p>
+
+<pre><code>
+java -classpath <all those JARs> akka.Main sample.hello.HelloWorld
+</code></pre>
+
+<p>
+This conveniently assumes placement of the above class definitions in package
+<code>sample.hello</code> and it further assumes that you have the required JAR files for
+<code>scala-library</code>, <code>typesafe-config</code> and <code>akka-actor</code> available.
+The easiest would be to manage these dependencies with a
+<a href="http://doc.akka.io/docs/akka/2.4-SNAPSHOT/intro/getting-started.html#Using_a_build_tool" target="_blank">build tool</a>.
+</p>
+
+<p>
+If you need more control of the startup code than what is provided by <code>akka.Main</code>
+you can easily write your own main class such as
+<a href="#code/src/main/java/sample/hello/Main2.java" class="shortcut">Main2.java</a>
+</p>
+
+<p>
+Try to run the <code>sample.hello.Main2</code> class
+by selecting it in the 'Main class' menu in the <a href="#run" class="shortcut">Run</a> tab.
+</p>
+
+</div>
+
+<div>
+
+<h2>Run with Maven</h2>
+
+<p>
+This sample also includes a Maven <a href="#code/pom.xml" class="shortcut">pom.xml</a>.
+</p>
+
+<p>
+You can run the main classes with <code>mvn</code> from a terminal window using the
+<a href="http://mojo.codehaus.org/exec-maven-plugin/" target="_blank">Exec Maven Plugin</a>.
+</p>
+
+<pre><code>
+mvn compile exec:java -Dexec.mainClass="akka.Main" -Dexec.args="sample.hello.HelloWorld"
+</code></pre>
+
+<pre><code>
+mvn compile exec:java -Dexec.mainClass="sample.hello.Main2"
+</code></pre>
+
+</div>
+
+</body>
+</html>

scripts/build/extra-build-steps.sh

@@ -103,3 +103,10 @@ mvncleantest "$java8_home" "akka-samples/akka-sample-fsm-java-lambda"
 mvncleantest "$java8_home" "akka-samples/akka-sample-persistence-java-lambda"
 
 mvncleantest "$java8_home" "akka-samples/akka-sample-supervision-java-lambda"
+
+sample_dir=akka-samples/akka-sample-main-java-lambda
+tmp="$script_dir/../../$sample_dir"
+try cd  "$tmp" "can't step into project directory: $tmp"
+export JAVA_HOME="$java8_home"
+try mvn clean compile exec:java -Dexec.mainClass="akka.Main" -Dexec.args="sample.hello.HelloWorld" "mvn execution in $sample_dir failed"
+try mvn exec:java -Dexec.mainClass="sample.hello.Main2" "mvn execution in $sample_dir failed"