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

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

@@ -0,0 +1,95 @@
+/**
+ *  Copyright (C) 2015 Typesafe <http://typesafe.com/>
+ */
+package docs.stream.javadsl.cookbook;
+
+import akka.actor.ActorSystem;
+import akka.event.Logging;
+import akka.event.LoggingAdapter;
+import akka.stream.ActorMaterializer;
+import akka.stream.Attributes;
+import akka.stream.Materializer;
+import akka.stream.javadsl.Sink;
+import akka.stream.javadsl.Source;
+import akka.testkit.DebugFilter;
+import akka.testkit.JavaTestKit;
+import com.typesafe.config.ConfigFactory;
+import docs.stream.SilenceSystemOut;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import scala.runtime.AbstractFunction0;
+import scala.runtime.BoxedUnit;
+
+import java.util.Arrays;
+
+public class RecipeLoggingElements extends RecipeTest {
+  static ActorSystem system;
+
+  @BeforeClass
+  public static void setup() {
+    system = ActorSystem.create("RecipeLoggingElements", ConfigFactory.parseString("akka.loglevel=DEBUG\nakka.loggers = [akka.testkit.TestEventListener]"));
+  }
+
+  @AfterClass
+  public static void tearDown() {
+    JavaTestKit.shutdownActorSystem(system);
+    system = null;
+  }
+
+  final Materializer mat = ActorMaterializer.create(system);
+
+  @Test
+  public void workWithPrintln() throws Exception {
+    new JavaTestKit(system) {
+      final SilenceSystemOut.System System = SilenceSystemOut.get(getTestActor());
+
+      {
+        final Source<String, BoxedUnit> mySource = Source.from(Arrays.asList("1", "2", "3"));
+
+        //#println-debug
+        mySource.map(elem -> {
+          System.out.println(elem);
+          return elem;
+        });
+        //#println-debug
+      }
+    };
+  }
+
+  @Test
+  public void workWithLog() throws Exception {
+    new JavaTestKit(system) {
+      private <T> T analyse(T i) {
+        return i;
+      }
+
+      {
+        final Source<String, BoxedUnit> mySource = Source.from(Arrays.asList("1", "2", "3"));
+
+        final int onElement = Logging.WarningLevel();
+        final int onFinish = Logging.ErrorLevel();
+        final int onFailure = Logging.ErrorLevel();
+
+        //#log-custom
+        // customise log levels
+        mySource.log("before-map")
+          .withAttributes(Attributes.createLogLevels(onElement, onFinish, onFailure))
+          .map(i -> analyse(i));
+
+        // or provide custom logging adapter
+        final LoggingAdapter adapter = Logging.getLogger(system, "customLogger");
+        mySource.log("custom", adapter);
+        //#log-custom
+
+        new DebugFilter("customLogger", "[custom] Element: ", false, false, 3).intercept(new AbstractFunction0  () {
+          public Void apply() {
+            mySource.log("custom", adapter).runWith(Sink.ignore(), mat);
+            return null;
+          }
+        }, system);
+      }
+    };
+  }
+
+}