INT-1448, INT-1442 accepted changes by Iwein, added small refactoring to AbstractMessageSplitter, added support for 'requires-reply' attribute, added test cases'

spring-integration-core/src/main/java/org/springframework/integration/config/SplitterFactoryBean.java

@@ -31,6 +31,7 @@ import org.springframework.util.StringUtils;
 public class SplitterFactoryBean extends AbstractMessageHandlerFactoryBean {
 
 	private volatile Long sendTimeout;
+	private volatile boolean requiresReply;
 
 	public void setSendTimeout(Long sendTimeout) {
 		this.sendTimeout = sendTimeout;
@@ -64,7 +65,14 @@ public class SplitterFactoryBean extends AbstractMessageHandlerFactoryBean {
 		if (this.sendTimeout != null) {
 			splitter.setSendTimeout(sendTimeout);
 		}
+		splitter.setRequiresReply(requiresReply);
 		return splitter;
 	}
+	public boolean isRequiresReply() {
+		return requiresReply;
+	}
 
+	public void setRequiresReply(boolean requiresReply) {
+		this.requiresReply = requiresReply;
+	}
 }

spring-integration-core/src/main/java/org/springframework/integration/splitter/AbstractMessageSplitter.java

@@ -20,7 +20,10 @@ import org.springframework.integration.Message;
 import org.springframework.integration.MessageHeaders;
 import org.springframework.integration.handler.AbstractReplyProducingMessageHandler;
 import org.springframework.integration.support.MessageBuilder;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.ObjectUtils;
 
+import java.lang.reflect.Array;
 import java.util.*;
 
 /**
@@ -38,7 +41,10 @@ public abstract class AbstractMessageSplitter extends AbstractReplyProducingMess
 	@SuppressWarnings("unchecked")
 	protected final Object handleRequestMessage(Message<?> message) {
 		Object result = this.splitMessage(message);
-		if (result == null) {
+		// return null if 'null', empty Collection or empty Array
+		if ( result == null ||
+			 (result instanceof Collection && CollectionUtils.isEmpty((Collection<?>)result)) ||
+			 (result.getClass().isArray() && ObjectUtils.isEmpty((Object[]) result))  ) { 	
 			return null;
 		}
 		MessageHeaders headers = message.getHeaders();
@@ -59,10 +65,6 @@ public abstract class AbstractMessageSplitter extends AbstractReplyProducingMess
 		List<MessageBuilder<?>> messageBuilders = new ArrayList<MessageBuilder<?>>();
 		if (result instanceof Collection) {
 			Collection<?> items = (Collection<?>) result;
-			//TODO put this return statement in a more obvious place
-			if(items.isEmpty()){
-				return null;
-			}
 			int sequenceNumber = 0;
 			int sequenceSize = items.size();
 			for (Object item : items) {

spring-integration-core/src/main/resources/org/springframework/integration/config/xml/spring-integration-2.0.xsd

@@ -1948,6 +1948,15 @@ Name of the header whose value to use.
 			<xsd:complexContent>
 				<xsd:extension base="expressionOrInnerEndpointDefinitionAware">
 					<xsd:attributeGroup ref="inputOutputChannelGroup" />
+					<xsd:attribute name="requires-reply" type="xsd:string" use="optional">
+						<xsd:annotation>
+							<xsd:documentation>
+	Specify whether the splitter method must return a non-null value. This value will be
+	FALSE by default, but if set to TRUE, a MessageHandlingException will be thrown when
+	the underlying service method (or expression) returns a NULL value.
+							</xsd:documentation>
+						</xsd:annotation>
+					</xsd:attribute>
 				</xsd:extension>
 			</xsd:complexContent>
 		</xsd:complexType>

spring-integration-core/src/test/java/org/springframework/integration/router/config/SplitterParserTests.java

@@ -19,13 +19,19 @@ package org.springframework.integration.router.config;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 
+import java.util.Collections;
+
 import org.junit.Test;
 
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 import org.springframework.integration.Message;
 import org.springframework.integration.MessageChannel;
+import org.springframework.integration.MessageHandlingException;
+import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.core.PollableChannel;
+import org.springframework.integration.endpoint.EventDrivenConsumer;
 import org.springframework.integration.message.GenericMessage;
+import org.springframework.integration.support.MessageBuilder;
 
 /**
  * @author Mark Fisher
@@ -88,5 +94,14 @@ public class SplitterParserTests {
 		assertEquals("test", result4.getPayload());
 		assertNull(output.receive(0));
 	}
+	
+	@Test(expected=MessageHandlingException.class)
+	public void splitterParserTestWithRequiresReply() {
+		ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
+				"splitterParserTests.xml", this.getClass());
+		context.start();
+		DirectChannel inputChannel = context.getBean("requiresReplyInput", DirectChannel.class);
+		inputChannel.send(MessageBuilder.withPayload(Collections.emptyList()).build());
+	}
 
 }

spring-integration-core/src/test/java/org/springframework/integration/router/config/splitterParserTests.xml

@@ -26,6 +26,11 @@
 			  ref="splitterImpl"
 	          input-channel="splitterImplementationInput"
 	          output-channel="output"/>
+	          
+	<splitter id="splitterImplementationRequiresReply"
+	          input-channel="requiresReplyInput"
+	          output-channel="output" 
+	          requires-reply="true"/>
 
 	<beans:bean id="splitterBean" class="org.springframework.integration.router.config.TestSplitterBean"/>
 

spring-integration-core/src/test/java/org/springframework/integration/splitter/DefaultSplitterTests.java

@@ -16,6 +16,17 @@
 
 package org.springframework.integration.splitter;
 
+import static junit.framework.Assert.assertEquals;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.nullValue;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
 import org.junit.Test;
 import org.springframework.integration.Message;
 import org.springframework.integration.channel.DirectChannel;
@@ -23,15 +34,6 @@ import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.endpoint.EventDrivenConsumer;
 import org.springframework.integration.support.MessageBuilder;
 
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-
-import static junit.framework.Assert.assertEquals;
-import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.nullValue;
-import static org.junit.Assert.*;
-
 /**
  * @author Mark Fisher
  * @author Iwein Fuld
@@ -104,5 +106,4 @@ public class DefaultSplitterTests {
 		Message<?> output = replyChannel.receive(15);
 		assertThat(output, is(nullValue()));
 	}
-
 }