Merge pull request #21081 from aartiguptaa

* pr/21081:
  Polish "Add support for customizing RSocketMessageHandler"
  Add support for customizing RSocketMessageHandler

Closes gh-21081

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/rsocket/RSocketMessageHandlerCustomizer.java

+/*
+ * Copyright 2012-2020 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.boot.autoconfigure.rsocket;
+
+import org.springframework.messaging.rsocket.annotation.support.RSocketMessageHandler;
+
+/**
+ * Callback interface that can be used to customize a {@link RSocketMessageHandler}.
+ *
+ * @author Aarti Gupta
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+@FunctionalInterface
+public interface RSocketMessageHandlerCustomizer {
+
+	/**
+	 * Customize the {@link RSocketMessageHandler}.
+	 * @param messageHandler the message handler to customize
+	 */
+	void customize(RSocketMessageHandler messageHandler);
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/rsocket/RSocketMessagingAutoConfiguration.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -19,6 +19,7 @@ package org.springframework.boot.autoconfigure.rsocket;
 import io.rsocket.RSocketFactory;
 import io.rsocket.transport.netty.server.TcpServerTransport;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -43,9 +44,11 @@ public class RSocketMessagingAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public RSocketMessageHandler messageHandler(RSocketStrategies rSocketStrategies) {
+	public RSocketMessageHandler messageHandler(RSocketStrategies rSocketStrategies,
+			ObjectProvider<RSocketMessageHandlerCustomizer> customizers) {
 		RSocketMessageHandler messageHandler = new RSocketMessageHandler();
 		messageHandler.setRSocketStrategies(rSocketStrategies);
+		customizers.orderedStream().forEach((customizer) -> customizer.customize(messageHandler));
 		return messageHandler;
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/rsocket/RSocketMessagingAutoConfigurationTests.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -26,6 +26,7 @@ import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.codec.StringDecoder;
 import org.springframework.messaging.rsocket.RSocketStrategies;
 import org.springframework.messaging.rsocket.annotation.support.RSocketMessageHandler;
+import org.springframework.util.MimeType;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -33,6 +34,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link RSocketMessagingAutoConfiguration}.
  *
  * @author Brian Clozel
+ * @author Madhura Bhave
  */
 class RSocketMessagingAutoConfigurationTests {
 
@@ -61,6 +63,14 @@ class RSocketMessagingAutoConfigurationTests {
 				.getBeanNames(RSocketMessageHandler.class).containsOnly("customMessageHandler"));
 	}
 
+	@Test
+	void shouldApplyMessageHandlerCustomizers() {
+		this.contextRunner.withUserConfiguration(CustomizerConfiguration.class).run((context) -> {
+			RSocketMessageHandler handler = context.getBean(RSocketMessageHandler.class);
+			assertThat(handler.getDefaultDataMimeType()).isEqualTo(MimeType.valueOf("application/json"));
+		});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class BaseConfiguration {
 
@@ -86,4 +96,14 @@ class RSocketMessagingAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomizerConfiguration {
+
+		@Bean
+		RSocketMessageHandlerCustomizer customizer() {
+			return (messageHandler) -> messageHandler.setDefaultDataMimeType(MimeType.valueOf("application/json"));
+		}
+
+	}
+
 }