Auto-configure Rabbit MessageConverter

If a `MessageConverter` bean is available, we now associate it to the
created `RabbitTemplate` and `RabbitListenerContainerFactory`. That way,
registering a custom `MessageConverter` is all that's needed.

The Rabbit auto-configuration is now using the new `ObjectProvider` that
offers a nicer API to detect if a primary candidate is available for
optional collaborators.

Closes gh-5088

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitAnnotationDrivenConfiguration.java

@@ -20,6 +20,8 @@ import org.springframework.amqp.rabbit.annotation.EnableRabbit;
 import org.springframework.amqp.rabbit.config.RabbitListenerConfigUtils;
 import org.springframework.amqp.rabbit.config.SimpleRabbitListenerContainerFactory;
 import org.springframework.amqp.rabbit.connection.ConnectionFactory;
+import org.springframework.amqp.support.converter.MessageConverter;
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -37,6 +39,9 @@ import org.springframework.context.annotation.Configuration;
 @ConditionalOnClass(EnableRabbit.class)
 class RabbitAnnotationDrivenConfiguration {
 
+	@Autowired
+	private ObjectProvider<MessageConverter> messageConverter;
+
 	@Autowired
 	private RabbitProperties properties;
 
@@ -44,6 +49,7 @@ class RabbitAnnotationDrivenConfiguration {
 	@ConditionalOnMissingBean
 	public SimpleRabbitListenerContainerFactoryConfigurer rabbitListenerContainerFactoryConfigurer() {
 		SimpleRabbitListenerContainerFactoryConfigurer configurer = new SimpleRabbitListenerContainerFactoryConfigurer();
+		configurer.setMessageConverter(this.messageConverter.getIfUnique());
 		configurer.setRabbitProperties(this.properties);
 		return configurer;
 	}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -25,6 +25,8 @@ import org.springframework.amqp.rabbit.connection.RabbitConnectionFactoryBean;
 import org.springframework.amqp.rabbit.core.RabbitAdmin;
 import org.springframework.amqp.rabbit.core.RabbitMessagingTemplate;
 import org.springframework.amqp.rabbit.core.RabbitTemplate;
+import org.springframework.amqp.support.converter.MessageConverter;
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -86,10 +88,18 @@ public class RabbitAutoConfiguration {
 	@Autowired
 	private ConnectionFactory connectionFactory;
 
+	@Autowired
+	private ObjectProvider<MessageConverter> messageConverter;
+
 	@Bean
 	@ConditionalOnMissingBean(RabbitTemplate.class)
 	public RabbitTemplate rabbitTemplate() {
-		return new RabbitTemplate(this.connectionFactory);
+		RabbitTemplate rabbitTemplate = new RabbitTemplate(this.connectionFactory);
+		MessageConverter messageConverter = this.messageConverter.getIfUnique();
+		if (messageConverter != null) {
+			rabbitTemplate.setMessageConverter(messageConverter);
+		}
+		return rabbitTemplate;
 	}
 
 	@Configuration

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/SimpleRabbitListenerContainerFactoryConfigurer.java

@@ -19,6 +19,7 @@ package org.springframework.boot.autoconfigure.amqp;
 import org.springframework.amqp.rabbit.config.SimpleRabbitListenerContainerFactory;
 import org.springframework.amqp.rabbit.connection.ConnectionFactory;
 import org.springframework.amqp.rabbit.listener.RabbitListenerContainerFactory;
+import org.springframework.amqp.support.converter.MessageConverter;
 import org.springframework.util.Assert;
 
 /**
@@ -29,8 +30,19 @@ import org.springframework.util.Assert;
  */
 public final class SimpleRabbitListenerContainerFactoryConfigurer {
 
+	private MessageConverter messageConverter;
+
 	private RabbitProperties rabbitProperties;
 
+	/**
+	 * Set the {@link MessageConverter} to use or {@code null} if the out-of-the-box
+	 * converter should be used.
+	 * @param messageConverter the {@link MessageConverter}
+	 */
+	void setMessageConverter(MessageConverter messageConverter) {
+		this.messageConverter = messageConverter;
+	}
+
 	/**
 	 * Set the {@link RabbitProperties} to use.
 	 * @param rabbitProperties the {@link RabbitProperties}
@@ -51,6 +63,9 @@ public final class SimpleRabbitListenerContainerFactoryConfigurer {
 		Assert.notNull(factory, "Factory must not be null");
 		Assert.notNull(connectionFactory, "ConnectionFactory must not be null");
 		factory.setConnectionFactory(connectionFactory);
+		if (this.messageConverter != null) {
+			factory.setMessageConverter(this.messageConverter);
+		}
 		RabbitProperties.Listener listenerConfig = this.rabbitProperties.getListener();
 		factory.setAutoStartup(listenerConfig.isAutoStartup());
 		if (listenerConfig.getAcknowledgeMode() != null) {

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/amqp/RabbitAutoConfigurationTests.java

@@ -42,6 +42,7 @@ import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -128,6 +129,15 @@ public class RabbitAutoConfigurationTests {
 		assertThat(connectionFactory.getVirtualHost()).isEqualTo("/");
 	}
 
+	@Test
+	public void testRabbitTemplateMessageConverters() {
+		load(MessageConvertersConfiguration.class);
+		RabbitTemplate rabbitTemplate = this.context
+				.getBean(RabbitTemplate.class);
+		assertThat(rabbitTemplate.getMessageConverter()).isSameAs(
+				this.context.getBean("myMessageConverter"));
+	}
+
 	@Test
 	public void testConnectionFactoryBackOff() {
 		load(TestConfiguration2.class);
@@ -187,7 +197,8 @@ public class RabbitAutoConfigurationTests {
 
 	@Test
 	public void testRabbitListenerContainerFactoryWithCustomSettings() {
-		load(TestConfiguration.class, "spring.rabbitmq.listener.autoStartup:false",
+		load(MessageConvertersConfiguration.class,
+				"spring.rabbitmq.listener.autoStartup:false",
 				"spring.rabbitmq.listener.acknowledgeMode:manual",
 				"spring.rabbitmq.listener.concurrency:5",
 				"spring.rabbitmq.listener.maxConcurrency:10",
@@ -204,6 +215,8 @@ public class RabbitAutoConfigurationTests {
 		assertThat(dfa.getPropertyValue("maxConcurrentConsumers")).isEqualTo(10);
 		assertThat(dfa.getPropertyValue("prefetchCount")).isEqualTo(40);
 		assertThat(dfa.getPropertyValue("txSize")).isEqualTo(20);
+		assertThat(dfa.getPropertyValue("messageConverter")).isSameAs(
+				this.context.getBean("myMessageConverter"));
 	}
 
 	@Test
@@ -325,6 +338,22 @@ public class RabbitAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class MessageConvertersConfiguration {
+
+		@Bean
+		@Primary
+		public MessageConverter myMessageConverter() {
+			return mock(MessageConverter.class);
+		}
+
+		@Bean
+		public MessageConverter anotherMessageConverter() {
+			return mock(MessageConverter.class);
+		}
+
+	}
+
 	@Configuration
 	@EnableRabbit
 	protected static class EnableRabbitConfiguration {

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -3734,7 +3734,8 @@ directly into your own beans:
 ----
 
 NOTE: {spring-amqp-javadoc}/rabbit/core/RabbitMessagingTemplate.{dc-ext}[`RabbitMessagingTemplate`]
-can be injected in a similar manner.
+can be injected in a similar manner. If a `MessageConverter` bean is defined, it is associated
+automatically to the auto-configured `AmqpTemplate`.
 
 Any `org.springframework.amqp.core.Queue` that is defined as a bean will be automatically
 used to declare a corresponding queue on the RabbitMQ instance if necessary.
@@ -3745,7 +3746,8 @@ used to declare a corresponding queue on the RabbitMQ instance if necessary.
 ==== Receiving a message
 When the Rabbit infrastructure is present, any bean can be annotated with
 `@RabbitListener` to create a listener endpoint. If no `RabbitListenerContainerFactory`
-has been defined, a default one is configured automatically.
+has been defined, a default one is configured automatically.  If a `MessageConverter`
+beans is defined, is is associated automatically to the default factory.
 
 The following component creates a listener endpoint on the `someQueue` queue: