Apply codecs auto-configuration to WebFlux

This commit introduces `CodecCustomizer`, a new callback-based interface
for customizing the codecs configuration for WebFlux server and client.

Instances of those customizers are applied to the `WebClient.Builder`
and to the `WebFluxAutoConfiguration` (which deals with both WebFlux and
WebFlux.fn).

For now, only Jackson codecs are auto-configured, by getting the
`ObjectMapper` instance created by Spring Boot. Other codecs can be
configured as soon as WebFlux supports those.

Closes gh-9166

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/codec/CodecsAutoConfiguration.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2017 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
+ *
+ *      http://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.http.codec;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
+import org.springframework.boot.web.codec.CodecCustomizer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.codec.CodecConfigurer;
+import org.springframework.http.codec.json.Jackson2JsonDecoder;
+import org.springframework.http.codec.json.Jackson2JsonEncoder;
+import org.springframework.util.MimeType;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration}
+ * for {@link org.springframework.core.codec.Encoder}s and {@link org.springframework.core.codec.Decoder}s.
+ * @author Brian Clozel
+ */
+@Configuration
+@ConditionalOnClass(CodecConfigurer.class)
+@AutoConfigureAfter(JacksonAutoConfiguration.class)
+public class CodecsAutoConfiguration {
+
+	@Configuration
+	@ConditionalOnClass(ObjectMapper.class)
+	static class JacksonCodecConfiguration {
+
+		@Bean
+		@ConditionalOnBean(ObjectMapper.class)
+		public CodecCustomizer jacksonCodecCustomizer(ObjectMapper objectMapper) {
+			return configurer -> {
+				CodecConfigurer.DefaultCodecs defaults = configurer.defaultCodecs();
+				defaults.jackson2Decoder(new Jackson2JsonDecoder(objectMapper, new MimeType[0]));
+				defaults.jackson2Encoder(new Jackson2JsonEncoder(objectMapper, new MimeType[0]));
+			};
+		}
+
+	}
+
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/codec/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2017 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
+ *
+ *      http://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.
+ */
+
+/**
+ * Auto-configuration for HTTP codecs.
+ */
+package org.springframework.boot.autoconfigure.http.codec;

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration.java

@@ -32,10 +32,12 @@ import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration;
 import org.springframework.boot.autoconfigure.validation.ValidatorAdapter;
 import org.springframework.boot.autoconfigure.web.ConditionalOnEnabledResourceChain;
 import org.springframework.boot.autoconfigure.web.ResourceProperties;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -46,6 +48,7 @@ import org.springframework.core.convert.converter.GenericConverter;
 import org.springframework.format.Formatter;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.http.CacheControl;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.util.ClassUtils;
 import org.springframework.validation.Validator;
 import org.springframework.web.reactive.config.DelegatingWebFluxConfiguration;
@@ -79,7 +82,7 @@ import org.springframework.web.reactive.result.view.ViewResolver;
 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
 @ConditionalOnClass(WebFluxConfigurer.class)
 @ConditionalOnMissingBean({ WebFluxConfigurationSupport.class })
-@AutoConfigureAfter(ReactiveWebServerAutoConfiguration.class)
+@AutoConfigureAfter({ ReactiveWebServerAutoConfiguration.class, CodecsAutoConfiguration.class })
 @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
 public class WebFluxAutoConfiguration {
 
@@ -98,6 +101,8 @@ public class WebFluxAutoConfiguration {
 
 		private final List<HandlerMethodArgumentResolver> argumentResolvers;
 
+		private final List<CodecCustomizer> codecCustomizers;
+
 		private final ResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer;
 
 		private final List<ViewResolver> viewResolvers;
@@ -105,12 +110,14 @@ public class WebFluxAutoConfiguration {
 		public WebFluxConfig(ResourceProperties resourceProperties,
 				WebFluxProperties webFluxProperties, ListableBeanFactory beanFactory,
 				ObjectProvider<List<HandlerMethodArgumentResolver>> resolvers,
+				ObjectProvider<List<CodecCustomizer>> codecCustomizers,
 				ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizer,
 				ObjectProvider<List<ViewResolver>> viewResolvers) {
 			this.resourceProperties = resourceProperties;
 			this.webFluxProperties = webFluxProperties;
 			this.beanFactory = beanFactory;
 			this.argumentResolvers = resolvers.getIfAvailable();
+			this.codecCustomizers = codecCustomizers.getIfAvailable();
 			this.resourceHandlerRegistrationCustomizer = resourceHandlerRegistrationCustomizer
 					.getIfAvailable();
 			this.viewResolvers = viewResolvers.getIfAvailable();
@@ -123,6 +130,13 @@ public class WebFluxAutoConfiguration {
 			}
 		}
 
+		@Override
+		public void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
+			if (this.codecCustomizers != null) {
+				this.codecCustomizers.forEach(codecCustomizer -> codecCustomizer.customize(configurer));
+			}
+		}
+
 		@Override
 		public void addResourceHandlers(ResourceHandlerRegistry registry) {
 			if (!this.resourceProperties.isAddMappings()) {

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/function/client/WebClientAutoConfiguration.java

@@ -20,14 +20,19 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration;
+import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.boot.web.reactive.function.client.WebClientCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Scope;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.core.annotation.Order;
 import org.springframework.util.CollectionUtils;
 import org.springframework.web.reactive.function.client.WebClient;
 
@@ -41,6 +46,7 @@ import org.springframework.web.reactive.function.client.WebClient;
  */
 @Configuration
 @ConditionalOnClass(WebClient.class)
+@AutoConfigureAfter(CodecsAutoConfiguration.class)
 public class WebClientAutoConfiguration {
 
 	private final WebClient.Builder webClientBuilder;
@@ -62,4 +68,19 @@ public class WebClientAutoConfiguration {
 	public WebClient.Builder webClientBuilder(List<WebClientCustomizer> customizers) {
 		return this.webClientBuilder.clone();
 	}
+
+	@Configuration
+	@ConditionalOnBean(CodecCustomizer.class)
+	protected static class WebClientCodecsConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		@Order(0)
+		public WebClientCodecCustomizer exchangeStrategiesCustomizer(
+				List<CodecCustomizer> codecCustomizers) {
+			return new WebClientCodecCustomizer(codecCustomizers);
+		}
+
+	}
+
 }

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/function/client/WebClientCodecCustomizer.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2017 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
+ *
+ *      http://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.web.reactive.function.client;
+
+import java.util.List;
+
+import org.springframework.boot.web.codec.CodecCustomizer;
+import org.springframework.boot.web.reactive.function.client.WebClientCustomizer;
+import org.springframework.web.reactive.function.client.ExchangeStrategies;
+import org.springframework.web.reactive.function.client.WebClient;
+
+/**
+ * {@link WebClientCustomizer} that configures codecs for the HTTP client.
+ * @author Brian Clozel
+ * @since 2.0.0
+ */
+public class WebClientCodecCustomizer implements WebClientCustomizer {
+
+	private final List<CodecCustomizer> codecCustomizers;
+
+	public WebClientCodecCustomizer(List<CodecCustomizer> codecCustomizers) {
+		this.codecCustomizers = codecCustomizers;
+	}
+
+	@Override
+	public void customize(WebClient.Builder webClientBuilder) {
+		webClientBuilder
+				.exchangeStrategies(ExchangeStrategies.builder()
+						.codecs(codecs -> {
+							this.codecCustomizers.forEach(codecCustomizer -> codecCustomizer.customize(codecs));
+						}).build());
+	}
+}

spring-boot-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -62,6 +62,7 @@ org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
 org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
 org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
 org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
+org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
 org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
 org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
 org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfigurationTests.java

@@ -32,6 +32,7 @@ import org.springframework.boot.autoconfigure.validation.ValidatorAdapter;
 import org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfigurationTests.Config;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.test.util.TestPropertyValues;
+import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.boot.web.reactive.context.GenericReactiveWebApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -39,6 +40,7 @@ import org.springframework.context.annotation.Import;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.core.io.ClassPathResource;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.util.ObjectUtils;
@@ -60,7 +62,9 @@ import org.springframework.web.reactive.result.view.ViewResolutionResultHandler;
 import org.springframework.web.reactive.result.view.ViewResolver;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link WebFluxAutoConfiguration}.
@@ -112,6 +116,15 @@ public class WebFluxAutoConfigurationTests {
 								HandlerMethodArgumentResolver.class));
 	}
 
+	@Test
+	public void shouldCustomizeCodecs() throws Exception {
+		load(CustomCodecCustomizers.class);
+		CodecCustomizer codecCustomizer =
+				this.context.getBean("firstCodecCustomizer", CodecCustomizer.class);
+		assertThat(codecCustomizer).isNotNull();
+		verify(codecCustomizer).customize(any(ServerCodecConfigurer.class));
+	}
+
 	@Test
 	public void shouldRegisterResourceHandlerMapping() throws Exception {
 		load();
@@ -316,6 +329,15 @@ public class WebFluxAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class CustomCodecCustomizers {
+
+		@Bean
+		public CodecCustomizer firstCodecCustomizer() {
+			return mock(CodecCustomizer.class);
+		}
+	}
+
 	@Configuration
 	protected static class ViewResolvers {
 

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/function/client/WebClientAutoConfigurationTests.java

@@ -22,12 +22,14 @@ import org.junit.After;
 import org.junit.Test;
 import reactor.core.publisher.Mono;
 
+import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.boot.web.reactive.function.client.WebClientCustomizer;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.client.reactive.ClientHttpConnector;
+import org.springframework.http.codec.CodecConfigurer;
 import org.springframework.web.reactive.function.client.WebClient;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -54,6 +56,17 @@ public class WebClientAutoConfigurationTests {
 		}
 	}
 
+	@Test
+	public void shouldCustomizeClientCodecs() throws Exception {
+		load(CodecConfiguration.class);
+		WebClient.Builder builder = this.context.getBean(WebClient.Builder.class);
+		CodecCustomizer codecCustomizer = this.context.getBean(CodecCustomizer.class);
+		WebClientCodecCustomizer clientCustomizer = this.context.getBean(WebClientCodecCustomizer.class);
+		builder.build();
+		assertThat(clientCustomizer).isNotNull();
+		verify(codecCustomizer).customize(any(CodecConfigurer.class));
+	}
+
 	@Test
 	public void webClientShouldApplyCustomizers() throws Exception {
 		load(WebClientCustomizerConfig.class);
@@ -104,6 +117,15 @@ public class WebClientAutoConfigurationTests {
 		this.context = ctx;
 	}
 
+	@Configuration
+	static class CodecConfiguration {
+
+		@Bean
+		public CodecCustomizer myCodecCustomizer() {
+			return mock(CodecCustomizer.class);
+		}
+	}
+
 	@Configuration
 	static class WebClientCustomizerConfig {
 

spring-boot-test-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -109,6 +109,7 @@ org.springframework.boot.test.autoconfigure.web.client.AutoConfigureWebClient=\
 org.springframework.boot.test.autoconfigure.web.client.WebClientRestTemplateAutoConfiguration,\
 org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
 org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
+org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
 org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration

spring-boot/src/main/java/org/springframework/boot/web/codec/CodecCustomizer.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2012-2017 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
+ *
+ *      http://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.web.codec;
+
+import org.springframework.http.codec.CodecConfigurer;
+
+/**
+ * Callback interface that can be used to customize codecs configuration
+ * for an HTTP client and/or server with a {@link CodecConfigurer}.
+ * @author Brian Clozel
+ * @since 2.0
+ */
+@FunctionalInterface
+public interface CodecCustomizer {
+
+	/**
+	 * Callback to customize a {@link CodecConfigurer} instance.
+	 * @param configurer codec configurer to customize
+	 */
+	void customize(CodecConfigurer configurer);
+
+}