ActorContext.getParent for Java API #22413

akka-docs/rst/java/code/jdocs/extension/ExtensionDocTest.java

@@ -0,0 +1,89 @@
+/**
+ * Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+package jdocs.extension;
+
+//#imports
+import akka.actor.*;
+import java.util.concurrent.atomic.AtomicLong;
+
+//#imports
+
+import jdocs.AbstractJavaTest;
+import org.junit.Test;
+
+public class ExtensionDocTest extends AbstractJavaTest {
+
+  static
+  //#extension
+  public class CountExtensionImpl implements Extension {
+    //Since this Extension is a shared instance
+    // per ActorSystem we need to be threadsafe
+    private final AtomicLong counter = new AtomicLong(0);
+
+    //This is the operation this Extension provides
+    public long increment() {
+      return counter.incrementAndGet();
+    }
+  }
+
+  //#extension
+
+  static
+  //#extensionid
+  public class CountExtension extends AbstractExtensionId<CountExtensionImpl>
+    implements ExtensionIdProvider {
+    //This will be the identifier of our CountExtension
+    public final static CountExtension CountExtensionProvider = new CountExtension();
+
+    private CountExtension() {}
+
+    //The lookup method is required by ExtensionIdProvider,
+    // so we return ourselves here, this allows us
+    // to configure our extension to be loaded when
+    // the ActorSystem starts up
+    public CountExtension lookup() {
+      return CountExtension.CountExtensionProvider; //The public static final
+    }
+
+    //This method will be called by Akka
+    // to instantiate our Extension
+    public CountExtensionImpl createExtension(ExtendedActorSystem system) {
+      return new CountExtensionImpl();
+    }
+  }
+
+  //#extensionid
+
+  static
+  //#extension-usage-actor
+  public class MyActor extends AbstractActor {
+    @Override
+    public Receive createReceive() {
+      return receiveBuilder()
+        .matchAny(msg -> {
+          // typically you would use static import of the
+          // CountExtension.CountExtensionProvider field
+          CountExtension.CountExtensionProvider.get(getContext().getSystem()).increment();
+        })
+        .build();
+    }
+  }
+
+  //#extension-usage-actor
+
+  @Test
+  public void demonstrateHowToCreateAndUseAnAkkaExtensionInJava() {
+    final ActorSystem system = null;
+    try {
+      //#extension-usage
+      // typically you would use static import of the
+      // CountExtension.CountExtensionProvider field
+      CountExtension.CountExtensionProvider.get(system).increment();
+      //#extension-usage
+    } catch (Exception e) {
+      //do nothing
+    }
+  }
+
+}