GH-1425: Configure ReplyPostProcessor via Factory

Resolves https://github.com/spring-projects/spring-amqp/issues/1425

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

@@ -17,6 +17,7 @@
 package org.springframework.amqp.rabbit.config;
 
 import java.util.Arrays;
+import java.util.function.Function;
 
 import org.aopalliance.aop.Advice;
 
@@ -26,6 +27,7 @@ import org.springframework.amqp.rabbit.listener.MessageListenerContainer;
 import org.springframework.amqp.rabbit.listener.RabbitListenerContainerFactory;
 import org.springframework.amqp.rabbit.listener.RabbitListenerEndpoint;
 import org.springframework.amqp.rabbit.listener.adapter.AbstractAdaptableMessageListener;
+import org.springframework.amqp.rabbit.listener.adapter.ReplyPostProcessor;
 import org.springframework.amqp.utils.JavaUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.retry.RecoveryCallback;
@@ -54,6 +56,8 @@ public abstract class BaseRabbitListenerContainerFactory<C extends MessageListen
 
 	private Advice[] adviceChain;
 
+	private Function<String, ReplyPostProcessor> replyPostProcessorProvider;
+
 	@Override
 	public abstract C createListenerContainer(RabbitListenerEndpoint endpoint);
 
@@ -108,6 +112,17 @@ public abstract class BaseRabbitListenerContainerFactory<C extends MessageListen
 		this.recoveryCallback = recoveryCallback;
 	}
 
+	/**
+	 * Set a function to provide a reply post processor; it will be used if there is no
+	 * replyPostProcessor on the rabbit listener annotation. The input parameter is the
+	 * listener id.
+	 * @param replyPostProcessorProvider the post processor.
+	 * @since 3.0
+	 */
+	public void setReplyPostProcessorProvider(Function<String, ReplyPostProcessor> replyPostProcessorProvider) {
+		this.replyPostProcessorProvider = replyPostProcessorProvider;
+	}
+
 	protected void applyCommonOverrides(@Nullable RabbitListenerEndpoint endpoint, C instance) {
 		if (endpoint != null) { // endpoint settings overriding default factory settings
 			JavaUtils.INSTANCE
@@ -130,6 +145,11 @@ public abstract class BaseRabbitListenerContainerFactory<C extends MessageListen
 						.acceptIfNotNull(endpoint.getReplyPostProcessor(), messageListener::setReplyPostProcessor)
 						.acceptIfNotNull(endpoint.getReplyContentType(), messageListener::setReplyContentType);
 				messageListener.setConverterWinsContentType(endpoint.isConverterWinsContentType());
+				if (endpoint.getReplyPostProcessor() == null && this.replyPostProcessorProvider != null) {
+					JavaUtils.INSTANCE
+							.acceptIfNotNull(this.replyPostProcessorProvider.apply(endpoint.getId()),
+									messageListener::setReplyPostProcessor);
+				}
 			}
 		}
 	}

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

@@ -237,6 +237,9 @@ public class EnableRabbitIntegrationTests extends NeedsManagementTests {
 	@Autowired
 	private MultiListenerValidatedJsonBean multiValidated;
 
+	@Autowired
+	private ReplyPostProcessor rpp;
+
 	@BeforeAll
 	public static void setUp() {
 		System.setProperty(RabbitListenerAnnotationBeanPostProcessor.RABBIT_EMPTY_STRING_ARGUMENTS_PROPERTY,
@@ -310,6 +313,8 @@ public class EnableRabbitIntegrationTests extends NeedsManagementTests {
 		this.registry.start();
 		assertThat(listenerContainer.isRunning()).isTrue();
 		listenerContainer.stop();
+		assertThat(listenerContainer.getMessageListener()).extracting("replyPostProcessor")
+				.isSameAs(this.rpp);
 	}
 
 	@Test
@@ -1690,14 +1695,22 @@ public class EnableRabbitIntegrationTests extends NeedsManagementTests {
 		}
 
 		@Bean
-		public SimpleRabbitListenerContainerFactory rabbitAutoStartFalseListenerContainerFactory() {
+		public SimpleRabbitListenerContainerFactory rabbitAutoStartFalseListenerContainerFactory(
+				ReplyPostProcessor rpp) {
+
 			SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
 			factory.setConnectionFactory(rabbitConnectionFactory());
 			factory.setReceiveTimeout(10L);
 			factory.setAutoStartup(false);
+			factory.setReplyPostProcessorProvider(id -> rpp);
 			return factory;
 		}
 
+		@Bean
+		ReplyPostProcessor rpp() {
+			return (in, out) -> out;
+		}
+
 		@Bean
 		public SimpleRabbitListenerContainerFactory jsonListenerContainerFactory() {
 			SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();

src/reference/asciidoc/amqp.adoc

@@ -3144,6 +3144,22 @@ public ReplyPostProcessor echoCustomHeader() {
 ----
 ====
 
+Starting with version 3.0, you can configure the post processor on the container factory instead of on the annotation.
+
+====
+[source, java]
+----
+factory.setReplyPostProcessorProvider(id -> (req, resp) -> {
+    resp.getMessageProperties().setHeader("myHeader", req.getMessageProperties().getHeader("myHeader"));
+    return resp;
+});
+----
+====
+
+The `id` parameter is the listener id.
+
+A setting on the annotation will supersede the factory setting.
+
 The `@SendTo` value is assumed as a reply `exchange` and `routingKey` pair that follows the `exchange/routingKey` pattern,
 where one of those parts can be omitted.
 The valid values are as follows:

src/reference/asciidoc/whats-new.adoc

@@ -37,7 +37,10 @@ When setting the container factory `consumerBatchEnabled` to `true`, the `batchL
 See <<receiving-batch>> for more infoprmation.
 
 `MessageConverter` s can now return `Optional.empty()` for a null value; this is currently implemented by the `Jackson2JsonMessageConverter`.
-See <<Jackson2JsonMessageConverter-from-message>> for more information.
+See <<Jackson2JsonMessageConverter-from-message>> for more information
+
+You can now configure a `ReplyPostProcessor` via the container factory rather than via a property on `@RabbitListener`.
+See <<async-annotation-driven-reply>> for more information.
 
 ==== Connection Factory Changes