Add null check after message conversion

AbstractMessageSendingTemplate now checks if MessageConverter.toMessage
returns null and raises an exception.

Issue: SPR-11370

spring-messaging/src/main/java/org/springframework/messaging/converter/CompositeMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original  author or authors.
+ * Copyright 2002-2014 the original  author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -106,4 +106,9 @@ public class CompositeMessageConverter implements MessageConverter {
 		return null;
 	}
 
+	@Override
+	public String toString() {
+		return "CompositeMessageConverter[contentTypeResolver=" + this.contentTypeResolver +
+				", converters=" + this.converters + "]";
+	}
 }

spring-messaging/src/main/java/org/springframework/messaging/converter/DefaultContentTypeResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,4 +56,8 @@ public class DefaultContentTypeResolver implements ContentTypeResolver {
 		return (mimeType != null) ? mimeType : this.defaultMimeType;
 	}
 
+	@Override
+	public String toString() {
+		return "DefaultContentTypeResolver[" + "defaultMimeType=" + this.defaultMimeType + "]";
+	}
 }

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessageSendingTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.MessagingException;
+import org.springframework.messaging.converter.MessageConversionException;
 import org.springframework.messaging.converter.MessageConverter;
 import org.springframework.messaging.converter.SimpleMessageConverter;
 import org.springframework.util.Assert;
@@ -130,6 +131,14 @@ public abstract class AbstractMessageSendingTemplate<D> implements MessageSendin
 
 		MessageHeaders messageHeaders = (headers != null) ? new MessageHeaders(headers) : null;
 		Message<?> message = this.converter.toMessage(payload, messageHeaders);
+
+		if (message == null) {
+			String payloadType = (payload != null) ? payload.getClass().getName() : null;
+			throw new MessageConversionException("Unable to convert payload type '"
+					+ payloadType + "', Content-Type=" + messageHeaders.get(MessageHeaders.CONTENT_TYPE)
+					+ ", converter=" + this.converter, null);
+		}
+
 		if (postProcessor != null) {
 			message = postProcessor.postProcessMessage(message);
 		}

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessagingTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Map;
 
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.converter.MessageConversionException;
 
 /**
  * An extension of {@link AbstractMessageSendingTemplate} that adds support for
@@ -116,9 +117,18 @@ public abstract class AbstractMessagingTemplate<D> extends AbstractMessageSendin
 
 		MessageHeaders messageHeaders = (headers != null) ? new MessageHeaders(headers) : null;
 		Message<?> requestMessage = getMessageConverter().toMessage(request, messageHeaders);
+
+		if (requestMessage == null) {
+			String payloadType = (request != null) ? request.getClass().getName() : null;
+			throw new MessageConversionException("Unable to convert payload type '"
+					+ payloadType + "', Content-Type=" + messageHeaders.get(MessageHeaders.CONTENT_TYPE)
+					+ ", converter=" + getMessageConverter(), null);
+		}
+
 		if (postProcessor != null) {
 			requestMessage = postProcessor.postProcessMessage(requestMessage);
 		}
+
 		Message<?> replyMessage = this.sendAndReceive(destination, requestMessage);
 		return (replyMessage != null) ? (T) getMessageConverter().fromMessage(replyMessage, targetClass) : null;
 	}

spring-messaging/src/test/java/org/springframework/messaging/core/MessageSendingTemplateTests.java

@@ -16,14 +16,20 @@
 
 package org.springframework.messaging.core;
 
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 
 import org.junit.Before;
 import org.junit.Test;
 
 import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.converter.*;
 import org.springframework.messaging.support.GenericMessage;
+import org.springframework.util.MimeType;
+import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.*;
 
@@ -45,7 +51,8 @@ public class MessageSendingTemplateTests {
 	public void setup() {
 		this.template = new TestMessageSendingTemplate();
 		this.postProcessor = new TestMessagePostProcessor();
-		this.headers = Collections.<String, Object>singletonMap("key", "value");
+		this.headers = new HashMap<>();
+		this.headers.put("key", "value");
 	}
 
 	@Test
@@ -144,6 +151,17 @@ public class MessageSendingTemplateTests {
 		assertSame(this.template.message, this.postProcessor.getMessage());
 	}
 
+	@Test(expected = MessageConversionException.class)
+	public void convertAndSendNoMatchingConverter() {
+
+		MessageConverter converter = new CompositeMessageConverter(
+				Arrays.asList(new MappingJackson2MessageConverter()), new DefaultContentTypeResolver());
+		this.template.setMessageConverter(converter);
+
+		this.headers.put(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_XML);
+		this.template.convertAndSend("home", "payload", new MessageHeaders(this.headers));
+	}
+
 
 	private static class TestMessageSendingTemplate extends AbstractMessageSendingTemplate<String> {