Add @RabbitListener replyPostProcessor

- allow customization of the reply message based on the request message.

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/annotation/RabbitListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -263,4 +263,14 @@
 	 */
 	String ackMode() default "";
 
+	/**
+	 * The bean name of a
+	 * {@link org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor} to post
+	 * process a response before it is sent.
+	 * @return the bean name.
+	 * @since 2.2.5
+	 * @see org.springframework.amqp.rabbit.listener.adapter.AbstractAdaptableMessageListener#setReplyPostProcessor(org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor)
+	 */
+	String replyPostProcessor() default "";
+
 }

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/annotation/RabbitListenerAnnotationBeanPostProcessor.java

@@ -51,6 +51,7 @@
 import org.springframework.amqp.rabbit.listener.RabbitListenerContainerFactory;
 import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
 import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistry;
+import org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor;
 import org.springframework.amqp.rabbit.listener.api.RabbitListenerErrorHandler;
 import org.springframework.aop.framework.Advised;
 import org.springframework.aop.support.AopUtils;
@@ -451,6 +452,7 @@ else if (errorHandler instanceof String) {
 		resolveExecutor(endpoint, rabbitListener, target, beanName);
 		resolveAdmin(endpoint, rabbitListener, target);
 		resolveAckMode(endpoint, rabbitListener);
+		resolvePostProcessor(endpoint, rabbitListener, target, beanName);
 		RabbitListenerContainerFactory<?> factory = resolveContainerFactory(rabbitListener, target, beanName);
 
 		this.registrar.registerEndpoint(endpoint, factory);
@@ -519,8 +521,26 @@ private void resolveExecutor(MethodRabbitListenerEndpoint endpoint, RabbitListen
 			}
 			catch (NoSuchBeanDefinitionException ex) {
 				throw new BeanInitializationException("Could not register rabbit listener endpoint on ["
-						+ execTarget + "] for bean " + beanName + ", no " + TaskExecutor.class.getSimpleName()
-						+ " with id '" + execBeanName + "' was found in the application context", ex);
+						+ execTarget + "] for bean " + beanName + ", no 'TaskExecutor' with id '"
+						+ execBeanName + "' was found in the application context", ex);
+			}
+		}
+	}
+
+	@SuppressWarnings("unchecked")
+	private void resolvePostProcessor(MethodRabbitListenerEndpoint endpoint, RabbitListener rabbitListener,
+			Object target, String beanName) {
+
+		String ppBeanName = resolve(rabbitListener.replyPostProcessor());
+		if (StringUtils.hasText(ppBeanName)) {
+			Assert.state(this.beanFactory != null, "BeanFactory must be set to obtain container factory by bean name");
+			try {
+				endpoint.setReplyPostProcessor(this.beanFactory.getBean(ppBeanName, ReplyPostProcessor.class));
+			}
+			catch (NoSuchBeanDefinitionException ex) {
+				throw new BeanInitializationException("Could not register rabbit listener endpoint on ["
+						+ target + "] for bean " + beanName + ", no 'ReplyPostProcessor' with id '"
+						+ ppBeanName + "' was found in the application context", ex);
 			}
 		}
 	}

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/config/AbstractRabbitListenerContainerFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -455,7 +455,8 @@ public C createListenerContainer(RabbitListenerEndpoint endpoint) {
 					.acceptIfNotNull(this.retryTemplate, messageListener::setRetryTemplate)
 					.acceptIfCondition(this.retryTemplate != null && this.recoveryCallback != null,
 							this.recoveryCallback, messageListener::setRecoveryCallback)
-					.acceptIfNotNull(this.defaultRequeueRejected, messageListener::setDefaultRequeueRejected);
+					.acceptIfNotNull(this.defaultRequeueRejected, messageListener::setDefaultRequeueRejected)
+					.acceptIfNotNull(endpoint.getReplyPostProcessor(), messageListener::setReplyPostProcessor);
 		}
 		initializeContainer(instance, endpoint);
 

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/AbstractRabbitListenerEndpoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -27,6 +27,7 @@
 import org.springframework.amqp.core.MessageListener;
 import org.springframework.amqp.core.Queue;
 import org.springframework.amqp.rabbit.batch.BatchingStrategy;
+import org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor;
 import org.springframework.amqp.support.converter.MessageConverter;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
@@ -90,6 +91,8 @@ public abstract class AbstractRabbitListenerEndpoint implements RabbitListenerEn
 
 	private AcknowledgeMode ackMode;
 
+	private ReplyPostProcessor replyPostProcessor;
+
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
 		this.beanFactory = beanFactory;
@@ -318,8 +321,22 @@ public AcknowledgeMode getAckMode() {
 		return this.ackMode;
 	}
 
-	public void setAckMode(AcknowledgeMode ackMode) {
-		this.ackMode = ackMode;
+	public void setAckMode(AcknowledgeMode mode) {
+		this.ackMode = mode;
+	}
+
+	@Override
+	public ReplyPostProcessor getReplyPostProcessor() {
+		return this.replyPostProcessor;
+	}
+
+	/**
+	 * Set a {@link ReplyPostProcessor} to post process a response message before it is sent.
+	 * @param replyPostProcessor the post processor.
+	 * @since 2.2.5
+	 */
+	public void setReplyPostProcessor(ReplyPostProcessor replyPostProcessor) {
+		this.replyPostProcessor = replyPostProcessor;
 	}
 
 	@Override

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/RabbitListenerEndpoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -18,6 +18,7 @@
 
 import org.springframework.amqp.core.AcknowledgeMode;
 import org.springframework.amqp.rabbit.batch.BatchingStrategy;
+import org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor;
 import org.springframework.amqp.support.converter.MessageConverter;
 import org.springframework.core.task.TaskExecutor;
 import org.springframework.lang.Nullable;
@@ -136,4 +137,15 @@ default AcknowledgeMode getAckMode() {
 		return null;
 	}
 
+	/**
+	 * Return a {@link ReplyPostProcessor} to post process a reply message before it is
+	 * sent.
+	 * @return the post processor.
+	 * @since 2.2.5
+	 */
+	@Nullable
+	default ReplyPostProcessor getReplyPostProcessor() {
+		return null;
+	}
+
 }

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/AbstractAdaptableMessageListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -117,6 +117,8 @@ public abstract class AbstractAdaptableMessageListener implements ChannelAwareMe
 
 	private boolean defaultRequeueRejected = true;
 
+	private ReplyPostProcessor replyPostProcessor;
+
 	/**
 	 * Set the routing key to use when sending response messages.
 	 * This will be applied in case of a request message that
@@ -242,6 +244,17 @@ public void setBeanResolver(BeanResolver beanResolver) {
 		this.evalContext.addPropertyAccessor(new MapAccessor());
 	}
 
+	/**
+	 * Set a {@link ReplyPostProcessor} to post process a response message before it is
+	 * sent. It is called after {@link #postProcessResponse(Message, Message)} which sets
+	 * up the correlationId header.
+	 * @param replyPostProcessor the post processor.
+	 * @since 2.2.5
+	 */
+	public void setReplyPostProcessor(ReplyPostProcessor replyPostProcessor) {
+		this.replyPostProcessor = replyPostProcessor;
+	}
+
 	/**
 	 * Return the converter that will convert incoming Rabbit messages to listener method arguments, and objects
 	 * returned from listener methods back to Rabbit messages.
@@ -413,6 +426,9 @@ protected void doHandleResult(InvocationResult resultArg, Message request, Chann
 			props.setTargetBean(resultArg.getBean());
 			props.setTargetMethod(resultArg.getMethod());
 			postProcessResponse(request, response);
+			if (this.replyPostProcessor != null) {
+				response = this.replyPostProcessor.apply(request, response);
+			}
 			Address replyTo = getReplyToAddress(request, source, resultArg);
 			sendResponse(channel, replyTo, response);
 		}
@@ -529,6 +545,7 @@ private Address evaluateReplyTo(Message request, Object source, Object result, E
 	 * @param replyTo the Rabbit ReplyTo string to use when sending. Currently interpreted to be the routing key.
 	 * @param messageIn the Rabbit message to send
 	 * @see #postProcessResponse(Message, Message)
+	 * @see #setReplyPostProcessor(ReplyPostProcessor)
 	 */
 	protected void sendResponse(Channel channel, Address replyTo, Message messageIn) {
 		Message message = messageIn;

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/ReplyPostProcessor.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.amqp.rabbit.listener.adapter;
+
+import java.util.function.BiFunction;
+
+import org.springframework.amqp.core.Message;
+
+/**
+ * A post processor for replies. The first parameter to the function is the request
+ * message, the second is the response message; it must return the modified (or a new)
+ * message. Use this, for example, if you want to copy additional headers from the request
+ * message.
+ *
+ * @author Gary Russell
+ * @since 2.2.5
+ *
+ */
+public interface ReplyPostProcessor extends BiFunction<Message, Message, Message> {
+
+}

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/annotation/EnableRabbitIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -77,6 +77,7 @@
 import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
 import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistry;
 import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
+import org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor;
 import org.springframework.amqp.rabbit.listener.api.ChannelAwareMessageListener;
 import org.springframework.amqp.rabbit.listener.api.RabbitListenerErrorHandler;
 import org.springframework.amqp.rabbit.support.ListenerExecutionFailedException;
@@ -417,6 +418,7 @@ public void endpointWithHeader() {
 				.isEqualTo("MyService");
 		assertThat((String) reply.getMessageProperties().getHeader("method"))
 				.isEqualTo("capitalizeWithHeader");
+		assertThat((String) reply.getMessageProperties().getHeader("prefix")).isEqualTo("prefix-");
 	}
 
 	@Test
@@ -1089,7 +1091,7 @@ public String multiQueuesConfig(String foo) {
 			return foo.toUpperCase() + foo;
 		}
 
-		@RabbitListener(queues = "test.header", group = "testGroup")
+		@RabbitListener(queues = "test.header", group = "testGroup", replyPostProcessor = "echoPrefixHeader")
 		public String capitalizeWithHeader(@Payload String content, @Header String prefix) {
 			return prefix + content.toUpperCase();
 		}
@@ -1806,6 +1808,14 @@ public DirectExchange internal() {
 			return directExchange;
 		}
 
+		@Bean
+		public ReplyPostProcessor echoPrefixHeader() {
+			return (req, resp) -> {
+				resp.getMessageProperties().setHeader("prefix", req.getMessageProperties().getHeader("prefix"));
+				return resp;
+			};
+		}
+
 	}
 
 	@RabbitListener(bindings = @QueueBinding

src/reference/asciidoc/amqp.adoc

@@ -2635,7 +2635,25 @@ factory.setBeforeSendReplyPostProcessors(msg -> {
 ----
 ====
 
+Starting with version 2.2.5, you can configure a `ReplyPostProcessor` to modify the reply message before it is sent; it is called after the `correlationId` header has been set up to match the request.
 
+====
+[source, java]
+----
+@RabbitListener(queues = "test.header", group = "testGroup", replyPostProcessor = "echoCustomHeader")
+public String capitalizeWithHeader(String in) {
+    return in.toUpperCase();
+}
+
+@Bean
+public ReplyPostProcessor echoCustomHeader() {
+    return (req, resp) -> {
+        resp.getMessageProperties().setHeader("myHeader", req.getMessageProperties().getHeader("myHeader"));
+        return resp;
+    };
+}
+----
+====
 
 The `@SendTo` value is assumed as a reply `exchange` and `routingKey` pair that follws the `exchange/routingKey` pattern,
 where one of those parts can be omitted.

src/reference/asciidoc/whats-new.adoc

@@ -63,6 +63,9 @@ When a `@RabbitListener` method returns a result, the bean and `Method` are now
 This allows configuration of a `beforeSendReplyMessagePostProcessor` to, for example, set a header in the reply to indicate which method was invoked on the server.
 See <<async-annotation-driven-reply>> for more information.
 
+You can now configure a `ReplyPostProcessor` to make modifications to a reply message before it is sent.
+See <<async-annotation-driven-reply>> for more information.
+
 ==== AMQP Logging Appenders Changes
 
 The Log4J and Logback `AmqpAppender` s now support a `verifyHostname` SSL option.