+sam #13890 Add Akka Main Activator template for Java 8

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

@@ -0,0 +1,19 @@
+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

@@ -0,0 +1,26 @@
+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

@@ -0,0 +1,28 @@
+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());
+    }
+  }
+}