Add notification api + sample usage

Add notification api + sample usage

Author: kmhigashioka

.classpath

@@ -6,24 +6,13 @@
 			<attribute name="maven.pomderived" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
 	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
 		<attributes>
 			<attribute name="optional" value="true"/>
 			<attribute name="maven.pomderived" value="true"/>
 			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-			<attribute name="test" value="true"/>
-		</attributes>
-	</classpathentry>
 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8">
 		<attributes>
 			<attribute name="maven.pomderived" value="true"/>

src/main/java/shortbus/AggregateException.java

@@ -0,0 +1,18 @@
+package shortbus;
+
+import java.util.List;
+
+public class AggregateException extends Exception {
+
+	private static final long serialVersionUID = 1L;
+	private List<Exception> exceptions;
+
+	public AggregateException(List<Exception> exceptions) {
+		this.exceptions = exceptions;
+	}
+
+	public List<Exception> getExceptions() {
+		return exceptions;
+	}
+
+}

src/main/java/shortbus/Mediator.java

@@ -11,4 +11,11 @@ public interface Mediator {
 	 * @return Response object
 	 */
 	public <T> Response<T> request(Request<T> request);
+
+	/**
+	 * Send a notification to all handler.
+	 * @param notification
+	 * @return
+	 */
+	public Response<Void> notify(Notification notification);
 }

src/main/java/shortbus/MediatorImpl.java

@@ -4,6 +4,8 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -19,6 +21,7 @@ public class MediatorImpl implements Mediator {
 
 	/**
 	 * Initializes a new instance of Mediator
+	 * 
 	 * @param ctx Application context of Spring
 	 */
 	public MediatorImpl(ApplicationContext ctx) {
@@ -29,19 +32,45 @@ public MediatorImpl(ApplicationContext ctx) {
 	public <T> Response<T> request(Request<T> request) {
 		Response<T> response = new Response<>();
 		try {
-			MediatorPlan<T> plan = new MediatorPlan<>(RequestHandler.class, "handle", request.getClass(), ctx);
+			MediatorPlanRequest<T> plan = new MediatorPlanRequest<>(RequestHandler.class, "handle", request.getClass(),
+					ctx);
 			response.data = plan.invoke(request);
 		} catch (Exception e) {
 			response.exception = e;
 		}
 		return response;
 	}
 
-	class MediatorPlan<T> {
+	@Override
+	public Response<Void> notify(Notification notification) {
+		Response<Void> response = new Response<>();
+		List<NotificationHandler<Notification>> handlers = MediatorPlanNotify.getInstances(ctx,
+				notification.getClass());
+		List<Exception> exceptions = null;
+
+		for (NotificationHandler<Notification> handler : handlers) {
+			try {
+				handler.handle(notification);
+			} catch (Exception ex) {
+				if (exceptions == null)
+					exceptions = new ArrayList<>();
+
+				exceptions.add(ex);
+			}
+		}
+
+		if (exceptions != null) {
+			response.exception = new AggregateException(exceptions);
+		}
+
+		return response;
+	}
+
+	class MediatorPlanRequest<T> {
 		Method handleMethod;
 		Object handlerInstanceBuilder;
 
-		public MediatorPlan(Class<?> handlerType, String handlerMethodName, Class<?> messageType,
+		public MediatorPlanRequest(Class<?> handlerType, String handlerMethodName, Class<?> messageType,
 				ApplicationContext context) throws NoSuchMethodException, SecurityException, ClassNotFoundException {
 			handlerInstanceBuilder = getBean(handlerType, messageType, context);
 			handleMethod = handlerInstanceBuilder.getClass().getDeclaredMethod(handlerMethodName, messageType);
@@ -70,4 +99,24 @@ public T invoke(Request<T> request)
 		}
 	}
 
+	static class MediatorPlanNotify {
+		public static List<NotificationHandler<Notification>> getInstances(ApplicationContext ctx,
+				Class<?> messageType) {
+			List<NotificationHandler<Notification>> instances = new ArrayList<>();
+
+			Map<String, ?> beans = ctx.getBeansOfType(NotificationHandler.class);
+			for (Entry<String, ?> entry : beans.entrySet()) {
+				Class<?> clazz = entry.getValue().getClass();
+				Type[] interfaces = clazz.getGenericInterfaces();
+				for (Type interace : interfaces) {
+					Type parameterType = ((ParameterizedType) interace).getActualTypeArguments()[0];
+					if (parameterType.equals(messageType)) {
+						instances.add((NotificationHandler<Notification>) entry.getValue());
+					}
+				}
+			}
+
+			return instances;
+		}
+	}
 }

src/main/java/shortbus/Notification.java

@@ -0,0 +1,9 @@
+package shortbus;
+
+/**
+ * Marker interface to represent a notification.
+ *
+ */
+public interface Notification {
+
+}

src/main/java/shortbus/NotificationHandler.java

@@ -0,0 +1,14 @@
+package shortbus;
+
+/**
+ * Defines a handler for all notification.
+ * 
+ * @param <T> Notification
+ */
+public interface NotificationHandler<T> {
+	/**
+	 * Handles all notification
+	 * @param Object parameter of Notification
+	 */
+	public void handle(T notification);
+}

src/test/java/shortbus/AnotherNotification.java

@@ -0,0 +1,5 @@
+package shortbus;
+
+public class AnotherNotification implements Notification {
+
+}

src/test/java/shortbus/Bar1Notification.java

@@ -0,0 +1,10 @@
+package shortbus;
+
+public class Bar1Notification implements NotificationHandler<FooNotification> {
+
+	@Override
+	public void handle(FooNotification notification) {
+		notification.counter++;
+	}
+
+}

src/test/java/shortbus/Bar2Notification.java

@@ -0,0 +1,10 @@
+package shortbus;
+
+public class Bar2Notification implements NotificationHandler<FooNotification> {
+
+	@Override
+	public void handle(FooNotification notification) {
+		notification.counter++;
+	}
+
+}

src/test/java/shortbus/Bar3Notification.java

@@ -0,0 +1,10 @@
+package shortbus;
+
+public class Bar3Notification implements NotificationHandler<AnotherNotification> {
+
+	@Override
+	public void handle(AnotherNotification notification) {
+		
+	}
+
+}

src/test/java/shortbus/BasicExampleTest.java

@@ -11,7 +11,8 @@
 
 @SpringBootTest
 @RunWith(SpringRunner.class)
-@ContextConfiguration(classes = { TestSetup.class, Bar.class })
+@ContextConfiguration(classes = { TestSetup.class, Bar.class, Bar1Notification.class, Bar2Notification.class,
+		Bar3Notification.class })
 public class BasicExampleTest {
 
 	@Autowired
@@ -36,4 +37,11 @@ public void requestResponseVoid() {
 		Response<Void> response = mediator.request(new FooVoid());
 		assertThat(response.data).isNull();
 	}
+
+	@Test
+	public void sendNotification() {
+		FooNotification notification = new FooNotification();
+		mediator.notify(notification);
+		assertThat(notification.counter).isEqualTo(2);
+	}
 }

src/test/java/shortbus/FooNotification.java

@@ -0,0 +1,5 @@
+package shortbus;
+
+public class FooNotification implements Notification {
+	public int counter = 0;
+}