Expose ServerCodecConfigurer as a bean

With this commit, ServerCodecConfigurer is now exposed as a bean in
order to be provided to DefaultServerWebExchange via
WebHttpHandlerBuilder and HttpWebHandlerAdapter. This allows
DefaultServerWebExchange to get configured codecs for reading form or
multipart requests.

Issue: SPR-14546

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurationSupport.java

@@ -81,8 +81,6 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 
 	private PathMatchConfigurer pathMatchConfigurer;
 
-	private ServerCodecConfigurer messageCodecsConfigurer;
-
 	private ApplicationContext applicationContext;
 
 
@@ -242,7 +240,7 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 	@Bean
 	public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
 		RequestMappingHandlerAdapter adapter = createRequestMappingHandlerAdapter();
-		adapter.setMessageCodecConfigurer(getMessageCodecsConfigurer());
+		adapter.setMessageCodecConfigurer(serverCodecConfigurer());
 		adapter.setWebBindingInitializer(getConfigurableWebBindingInitializer());
 		adapter.setReactiveAdapterRegistry(webFluxAdapterRegistry());
 
@@ -267,16 +265,15 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 	}
 
 	/**
-	 * Main method to access the configurer for HTTP message readers and writers.
+	 * Return the configurer for HTTP message readers and writers.
 	 * <p>Use {@link #configureHttpMessageCodecs(ServerCodecConfigurer)} to
 	 * configure the readers and writers.
 	 */
-	protected final ServerCodecConfigurer getMessageCodecsConfigurer() {
-		if (this.messageCodecsConfigurer == null) {
-			this.messageCodecsConfigurer = ServerCodecConfigurer.create();
-			configureHttpMessageCodecs(this.getMessageCodecsConfigurer());
-		}
-		return this.messageCodecsConfigurer;
+	@Bean
+	public ServerCodecConfigurer serverCodecConfigurer() {
+		ServerCodecConfigurer serverCodecConfigurer = ServerCodecConfigurer.create();
+		configureHttpMessageCodecs(serverCodecConfigurer);
+		return serverCodecConfigurer;
 	}
 
 	/**
@@ -372,13 +369,13 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 
 	@Bean
 	public ResponseEntityResultHandler responseEntityResultHandler() {
-		return new ResponseEntityResultHandler(getMessageCodecsConfigurer().getWriters(),
+		return new ResponseEntityResultHandler(serverCodecConfigurer().getWriters(),
 				webFluxContentTypeResolver(), webFluxAdapterRegistry());
 	}
 
 	@Bean
 	public ResponseBodyResultHandler responseBodyResultHandler() {
-		return new ResponseBodyResultHandler(getMessageCodecsConfigurer().getWriters(),
+		return new ResponseBodyResultHandler(serverCodecConfigurer().getWriters(),
 				webFluxContentTypeResolver(), webFluxAdapterRegistry());
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/DispatcherHandlerIntegrationTests.java

@@ -125,13 +125,13 @@ public class DispatcherHandlerIntegrationTests extends AbstractHttpHandlerIntegr
 					new HandlerStrategies() {
 						@Override
 						public Supplier<Stream<HttpMessageReader<?>>> messageReaders() {
-							return () -> getMessageCodecsConfigurer().getReaders().stream()
+							return () -> serverCodecConfigurer().getReaders().stream()
 									.map(reader -> (HttpMessageReader<?>) reader);
 						}
 
 						@Override
 						public Supplier<Stream<HttpMessageWriter<?>>> messageWriters() {
-							return () -> getMessageCodecsConfigurer().getWriters().stream()
+							return () -> serverCodecConfigurer().getWriters().stream()
 									.map(writer -> (HttpMessageWriter<?>) writer);
 						}
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/SessionAttributeMethodArgumentResolverTests.java

@@ -31,6 +31,7 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.annotation.SynthesizingMethodParameter;
 import org.springframework.format.support.DefaultFormattingConversionService;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpResponse;
@@ -81,7 +82,7 @@ public class SessionAttributeMethodArgumentResolverTests {
 		WebSessionManager sessionManager = new MockWebSessionManager(this.session);
 
 		ServerHttpRequest request = MockServerHttpRequest.get("/").build();
-		this.exchange = new DefaultServerWebExchange(request, new MockServerHttpResponse(), sessionManager);
+		this.exchange = new DefaultServerWebExchange(request, new MockServerHttpResponse(), sessionManager, ServerCodecConfigurer.create());
 
 		this.handleMethod = ReflectionUtils.findMethod(getClass(), "handleWithSessionAttribute", (Class<?>[]) null);
 	}