DATAREST-970 - AnnotationEventHandlerInvoker now considers order of event handler methods.

We now make sure that an @Order annotation on annotated event handler methods are considered and the methods are invoked in the defined order.

Non-annotation-based event handlers don't suffer from the same problem as they're ApplicationListener instances directly so that the container will enforce the correct ordering in case @Order is used or Ordered is implemented.

Some cleanup in EventHandlerMethod.

Original pull request: #248.

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/event/AnnotatedEventHandlerInvokerUnitTests.java

@@ -20,6 +20,7 @@ import static org.junit.Assert.*;
 
 import org.junit.Test;
 import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.core.annotation.Order;
 import org.springframework.data.rest.core.annotation.HandleBeforeCreate;
 import org.springframework.data.rest.core.annotation.RepositoryEventHandler;
 import org.springframework.data.rest.core.domain.Person;
@@ -32,6 +33,7 @@ import org.springframework.util.MultiValueMap;
  *
  * @author Oliver Gierke
  * @author Fabian Trampusch
+ * @author Joseph Valerio
  */
 public class AnnotatedEventHandlerInvokerUnitTests {
 
@@ -65,6 +67,24 @@ public class AnnotatedEventHandlerInvokerUnitTests {
 		assertThat(sampleHandler.wasCalled, is(true));
 	}
 
+	@Test // DATAREST-970
+	public void invokesEventHandlerInOrderMethods() {
+
+		SampleOrderEventHandler1 orderHandler1 = new SampleOrderEventHandler1();
+		SampleOrderEventHandler2 orderHandler2 = new SampleOrderEventHandler2();
+
+		AnnotatedEventHandlerInvoker invoker = new AnnotatedEventHandlerInvoker();
+		invoker.postProcessAfterInitialization(orderHandler1, "orderHandler1");
+		invoker.postProcessAfterInitialization(orderHandler2, "orderHandler2");
+
+		invoker.onApplicationEvent(new BeforeCreateEvent(new Person("Dave", "Matthews")));
+
+		assertThat(orderHandler1.wasCalled, is(true));
+		assertThat(orderHandler2.wasCalled, is(true));
+
+		assertThat(orderHandler1.timestamp, is(greaterThan(orderHandler2.timestamp)));
+	}
+
 	@RepositoryEventHandler
 	static class Sample {
 
@@ -82,4 +102,32 @@ public class AnnotatedEventHandlerInvokerUnitTests {
 			wasCalled = true;
 		}
 	}
+
+	@RepositoryEventHandler
+	static class SampleOrderEventHandler1 {
+
+		boolean wasCalled = false;
+		long timestamp;
+
+		@Order(2)
+		@HandleBeforeCreate
+		private void method(Person sample) {
+			wasCalled = true;
+			timestamp = System.nanoTime();
+		}
+	}
+
+	@RepositoryEventHandler
+	static class SampleOrderEventHandler2 {
+
+		boolean wasCalled = false;
+		long timestamp;
+
+		@Order(1)
+		@HandleBeforeCreate
+		private void method(Person sample) {
+			wasCalled = true;
+			timestamp = System.nanoTime();
+		}
+	}
 }