Fix review remarks on Servlet.fn

This commit incoporates the remarks made during the Servlet.fn review.

See gh-21490

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultEntityResponseBuilder.java

@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.function;
 
 import java.io.IOException;
+import java.lang.reflect.Type;
 import java.net.URI;
 import java.time.Instant;
 import java.time.ZonedDateTime;
@@ -39,12 +40,14 @@ import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
+import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.server.ServletServerHttpResponse;
 import org.springframework.lang.Nullable;
@@ -64,7 +67,7 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 
 	private final T entity;
 
-	private final BuilderFunction<T> builderFunction;
+	private final Type entityType;
 
 	private int status = HttpStatus.OK.value();
 
@@ -73,9 +76,9 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 	private final MultiValueMap<String, Cookie> cookies = new LinkedMultiValueMap<>();
 
 
-	private DefaultEntityResponseBuilder(T entity, BuilderFunction<T> builderFunction) {
+	private DefaultEntityResponseBuilder(T entity, @Nullable Type entityType) {
 		this.entity = entity;
-		this.builderFunction = builderFunction;
+		this.entityType = (entityType != null) ? entityType : entity.getClass();
 	}
 
 	@Override
@@ -185,9 +188,23 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 		return this;
 	}
 
+	@SuppressWarnings({"rawtypes", "unchecked"})
 	@Override
 	public EntityResponse<T> build() {
-		return this.builderFunction.build(this.status, this.headers, this.cookies, this.entity);
+		if (this.entity instanceof CompletionStage) {
+			CompletionStage completionStage = (CompletionStage) this.entity;
+			return new CompletionStageEntityResponse(this.status, this.headers, this.cookies,
+					completionStage, this.entityType);
+		}
+		else if (this.entity instanceof Publisher) {
+			Publisher publisher = (Publisher) this.entity;
+			return new PublisherEntityResponse(this.status, this.headers, this.cookies, publisher,
+					this.entityType);
+		}
+		else {
+			return new DefaultEntityResponse<>(this.status, this.headers, this.cookies, this.entity,
+					this.entityType);
+		}
 	}
 
 
@@ -195,42 +212,16 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 	 * Return a new {@link EntityResponse.Builder} from the given object.
 	 */
 	public static <T> EntityResponse.Builder<T> fromObject(T t) {
-		return new DefaultEntityResponseBuilder<>(t, DefaultEntityResponse::new);
-	}
-
-	/**
-	 * Return a new {@link EntityResponse.Builder} from the given completion stage.
-	 */
-	public static <T> EntityResponse.Builder<CompletionStage<T>> fromCompletionStage(
-			CompletionStage<T> completionStage) {
-		return new DefaultEntityResponseBuilder<>(completionStage,
-				CompletionStageEntityResponse::new);
+		return new DefaultEntityResponseBuilder<>(t, null);
 	}
 
 	/**
-	 * Return a new {@link EntityResponse.Builder} from the given Reactive Streams publisher.
+	 * Return a new {@link EntityResponse.Builder} from the given object and type reference.
 	 */
-	public static <T> EntityResponse.Builder<Publisher<T>> fromPublisher(Publisher<T> publisher) {
-		return new DefaultEntityResponseBuilder<>(publisher, PublisherEntityResponse::new);
+	public static <T> EntityResponse.Builder<T> fromObject(T t, ParameterizedTypeReference<?> bodyType) {
+		return new DefaultEntityResponseBuilder<>(t, bodyType.getType());
 	}
 
-	@SuppressWarnings("unchecked")
-	private static <T> HttpMessageConverter<T> cast(HttpMessageConverter<?> messageConverter) {
-		return (HttpMessageConverter<T>) messageConverter;
-	}
-
-
-	/**
-	 * Defines contract for building {@link EntityResponse} instances.
-	 */
-	private interface BuilderFunction<T> {
-
-		EntityResponse<T> build(int statusCode, HttpHeaders headers,
-				MultiValueMap<String, Cookie> cookies, T entity);
-
-	}
-
-
 	/**
 	 * Default {@link EntityResponse} implementation for synchronous bodies.
 	 */
@@ -240,12 +231,15 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 
 		private final T entity;
 
+		private final Type entityType;
+
 
 		public DefaultEntityResponse(int statusCode, HttpHeaders headers,
-				MultiValueMap<String, Cookie> cookies, T entity) {
+				MultiValueMap<String, Cookie> cookies, T entity, Type entityType) {
 
 			super(statusCode, headers, cookies);
 			this.entity = entity;
+			this.entityType = entityType;
 		}
 
 		@Override
@@ -258,11 +252,12 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 				HttpServletResponse servletResponse, Context context)
 				throws ServletException, IOException {
 
-			writeEntityWithMessageConverters(this.entity, servletRequest, servletResponse, context);
+			writeEntityWithMessageConverters(this.entity, servletRequest,servletResponse, context);
 
 			return null;
 		}
 
+		@SuppressWarnings("unchecked")
 		protected void writeEntityWithMessageConverters(Object entity,
 				HttpServletRequest request, HttpServletResponse response,
 				ServerResponse.Context context)
@@ -271,30 +266,39 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 			ServletServerHttpResponse serverResponse = new ServletServerHttpResponse(response);
 
 			MediaType contentType = getContentType(response);
-			Class<?> entityType = entity.getClass();
-
-			HttpMessageConverter<Object> messageConverter = context.messageConverters().stream()
-					.filter(converter -> converter.canWrite(entityType, contentType))
-					.findFirst()
-					.map(DefaultEntityResponseBuilder::cast)
-					.orElseThrow(() -> new HttpMediaTypeNotAcceptableException(
-							producibleMediaTypes(context.messageConverters(), entityType)));
+			Class<?> entityClass = entity.getClass();
+
+			for (HttpMessageConverter<?> messageConverter : context.messageConverters()) {
+				if (messageConverter instanceof GenericHttpMessageConverter<?>) {
+					GenericHttpMessageConverter<Object> genericMessageConverter =
+							(GenericHttpMessageConverter<Object>) messageConverter;
+					if (genericMessageConverter.canWrite(this.entityType, entityClass, contentType)) {
+						genericMessageConverter.write(entity, this.entityType, contentType, serverResponse);
+						return;
+					}
+				}
+				if (messageConverter.canWrite(entityClass, contentType)) {
+					((HttpMessageConverter<Object>)messageConverter).write(entity, contentType, serverResponse);
+					return;
+				}
+			}
 
-			messageConverter.write(entity, contentType, serverResponse);
+			List<MediaType> producibleMediaTypes = producibleMediaTypes(context.messageConverters(), entityClass);
+			throw new HttpMediaTypeNotAcceptableException(producibleMediaTypes);
 		}
 
 		@Nullable
-		private MediaType getContentType(HttpServletResponse response) {
+		private static MediaType getContentType(HttpServletResponse response) {
 			try {
-				return MediaType.parseMediaType(response.getContentType());
+				return MediaType.parseMediaType(response.getContentType()).removeQualityValue();
 			}
 			catch (InvalidMediaTypeException ex) {
 				return null;
 			}
 		}
 
-		protected final void tryWriteEntityWithMessageConverters(Object entity,
-						HttpServletRequest request, HttpServletResponse response,
+		protected void tryWriteEntityWithMessageConverters(Object entity,
+				HttpServletRequest request, HttpServletResponse response,
 						ServerResponse.Context context) {
 			try {
 				writeEntityWithMessageConverters(entity, request, response, context);
@@ -323,10 +327,10 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 	private static class CompletionStageEntityResponse<T>
 			extends DefaultEntityResponse<CompletionStage<T>> {
 
-		public CompletionStageEntityResponse(int statusCode,
-				HttpHeaders headers,
-				MultiValueMap<String, Cookie> cookies, CompletionStage<T> entity) {
-			super(statusCode, headers, cookies, entity);
+		public CompletionStageEntityResponse(int statusCode, HttpHeaders headers,
+				MultiValueMap<String, Cookie> cookies, CompletionStage<T> entity,
+				Type entityType) {
+			super(statusCode, headers, cookies, entity, entityType);
 		}
 
 		@Override
@@ -338,6 +342,7 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 			entity().whenComplete((entity, throwable) -> {
 				try {
 					if (entity != null) {
+
 						tryWriteEntityWithMessageConverters(entity,
 								(HttpServletRequest) asyncContext.getRequest(),
 								(HttpServletResponse) asyncContext.getResponse(),
@@ -358,8 +363,9 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 	private static class PublisherEntityResponse<T> extends DefaultEntityResponse<Publisher<T>> {
 
 		public PublisherEntityResponse(int statusCode, HttpHeaders headers,
-				MultiValueMap<String, Cookie> cookies, Publisher<T> entity) {
-			super(statusCode, headers, cookies, entity);
+				MultiValueMap<String, Cookie> cookies, Publisher<T> entity,
+				Type entityType) {
+			super(statusCode, headers, cookies, entity, entityType);
 		}
 
 		@Override
@@ -425,6 +431,8 @@ class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T> {
 						(HttpServletRequest) this.asyncContext.getRequest(),
 						(HttpServletResponse) this.asyncContext.getResponse(),
 						this.context);
+
+				this.asyncContext.complete();
 			}
 
 			@Override

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java

@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.function;
 
 import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.net.InetSocketAddress;
 import java.net.URI;
@@ -48,7 +49,6 @@ import org.springframework.http.MediaType;
 import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.server.ServletServerHttpRequest;
-import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -152,35 +152,42 @@ class DefaultServerRequest implements ServerRequest {
 	@Override
 	public <T> T body(ParameterizedTypeReference<T> bodyType) throws IOException, ServletException {
 		Type type = bodyType.getType();
-		Class<?> contextClass = null;
+		return bodyInternal(type, bodyClass(type));
+	}
+
+	static Class<?> bodyClass(Type type) {
 		if (type instanceof Class) {
-			contextClass = (Class<?>) type;
+			return (Class<?>) type;
 		}
-		return bodyInternal(type, contextClass);
+		if (type instanceof ParameterizedType) {
+			ParameterizedType parameterizedType = (ParameterizedType) type;
+			if (parameterizedType.getRawType() instanceof Class) {
+				return (Class<?>) parameterizedType.getRawType();
+			}
+		}
+		return Object.class;
 	}
 
 	@SuppressWarnings("unchecked")
-	private <T> T bodyInternal(Type type, @Nullable Class<?> contextClass)
+	private <T> T bodyInternal(Type bodyType, Class<?> bodyClass)
 			throws ServletException, IOException {
 
 		MediaType contentType =
 				this.headers.contentType().orElse(MediaType.APPLICATION_OCTET_STREAM);
 
 		for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
-			if (messageConverter instanceof GenericHttpMessageConverter<?>) {
+			if (messageConverter instanceof GenericHttpMessageConverter) {
 				GenericHttpMessageConverter<T> genericMessageConverter =
 						(GenericHttpMessageConverter<T>) messageConverter;
-				if (genericMessageConverter.canRead(type, contextClass, contentType)) {
-					return genericMessageConverter.read(type, contextClass, this.serverHttpRequest);
+				if (genericMessageConverter.canRead(bodyType, bodyClass, contentType)) {
+					return genericMessageConverter.read(bodyType, bodyClass, this.serverHttpRequest);
 				}
 			}
-			else {
-				if (messageConverter.canRead(contextClass, contentType)) {
-					HttpMessageConverter<T> theConverter =
-							(HttpMessageConverter<T>) messageConverter;
-					Class<? extends T> clazz = (Class<? extends T>) contextClass;
-					return theConverter.read(clazz, this.serverHttpRequest);
-				}
+			if (messageConverter.canRead(bodyClass, contentType)) {
+				HttpMessageConverter<T> theConverter =
+						(HttpMessageConverter<T>) messageConverter;
+				Class<? extends T> clazz = (Class<? extends T>) bodyClass;
+				return theConverter.read(clazz, this.serverHttpRequest);
 			}
 		}
 		throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);
@@ -196,6 +203,11 @@ class DefaultServerRequest implements ServerRequest {
 		return this.attributes;
 	}
 
+	@Override
+	public Optional<String> param(String name) {
+		return Optional.ofNullable(servletRequest().getParameter(name));
+	}
+
 	@Override
 	public MultiValueMap<String, String> params() {
 		return this.params;

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java

@@ -46,7 +46,6 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -239,35 +238,29 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 		@Override
 		public <T> T body(ParameterizedTypeReference<T> bodyType) throws IOException, ServletException {
 			Type type = bodyType.getType();
-			Class<?> contextClass = null;
-			if (type instanceof Class) {
-				contextClass = (Class<?>) type;
-			}
-			return bodyInternal(type, contextClass);
+			return bodyInternal(type, DefaultServerRequest.bodyClass(type));
 		}
 
 		@SuppressWarnings("unchecked")
-		private <T> T bodyInternal(Type type, @Nullable Class<?> contextClass)
+		private <T> T bodyInternal(Type bodyType, Class<?> bodyClass)
 				throws ServletException, IOException {
 
 			HttpInputMessage inputMessage = new BuiltInputMessage();
 			MediaType contentType = headers().contentType().orElse(MediaType.APPLICATION_OCTET_STREAM);
 
 			for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
-				if (messageConverter instanceof GenericHttpMessageConverter<?>) {
+				if (messageConverter instanceof GenericHttpMessageConverter) {
 					GenericHttpMessageConverter<T> genericMessageConverter =
 							(GenericHttpMessageConverter<T>) messageConverter;
-					if (genericMessageConverter.canRead(type, contextClass, contentType)) {
-						return genericMessageConverter.read(type, contextClass, inputMessage);
+					if (genericMessageConverter.canRead(bodyType, bodyClass, contentType)) {
+						return genericMessageConverter.read(bodyType, bodyClass, inputMessage);
 					}
 				}
-				else {
-					if (messageConverter.canRead(contextClass, contentType)) {
-						HttpMessageConverter<T> theConverter =
-								(HttpMessageConverter<T>) messageConverter;
-						Class<? extends T> clazz = (Class<? extends T>) contextClass;
-						return theConverter.read(clazz, inputMessage);
-					}
+				if (messageConverter.canRead(bodyClass, contentType)) {
+					HttpMessageConverter<T> theConverter =
+							(HttpMessageConverter<T>) messageConverter;
+					Class<? extends T> clazz = (Class<? extends T>) bodyClass;
+					return theConverter.read(clazz, inputMessage);
 				}
 			}
 			throw new HttpMediaTypeNotSupportedException(contentType, Collections.emptyList());

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerResponseBuilder.java

@@ -29,7 +29,6 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.CompletionStage;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
@@ -38,8 +37,7 @@ import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import org.reactivestreams.Publisher;
-
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -196,16 +194,8 @@ class DefaultServerResponseBuilder implements ServerResponse.BodyBuilder {
 	}
 
 	@Override
-	public ServerResponse asyncBody(CompletionStage<?> asyncBody) {
-		return DefaultEntityResponseBuilder.fromCompletionStage(asyncBody)
-				.headers(this.headers)
-				.status(this.statusCode)
-				.build();
-	}
-
-	@Override
-	public ServerResponse asyncBody(Publisher<?> futureBody) {
-		return DefaultEntityResponseBuilder.fromPublisher(futureBody)
+	public <T> ServerResponse body(T body, ParameterizedTypeReference<T> bodyType) {
+		return DefaultEntityResponseBuilder.fromObject(body, bodyType)
 				.headers(this.headers)
 				.status(this.statusCode)
 				.build();

spring-webmvc/src/main/java/org/springframework/web/servlet/function/EntityResponse.java

@@ -20,12 +20,10 @@ import java.net.URI;
 import java.time.Instant;
 import java.time.ZonedDateTime;
 import java.util.Set;
-import java.util.concurrent.CompletionStage;
 import java.util.function.Consumer;
 import javax.servlet.http.Cookie;
 
-import org.reactivestreams.Publisher;
-
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -61,24 +59,16 @@ public interface EntityResponse<T> extends ServerResponse {
 	}
 
 	/**
-	 * Create a builder for an asynchronous body supplied by the given {@link CompletionStage}.
-	 * @param completionStage the supplier of the response body
-	 * @param <T> the type of the elements contained in the publisher
+	 * Create a builder with the given object and type reference.
+	 * @param t the object that represents the body of the response
+	 * @param entityType the type of the entity, used to capture the generic type
+	 * @param <T> the type of element contained in the publisher
 	 * @return the created builder
 	 */
-	static <T> Builder<CompletionStage<T>> fromCompletionStage(CompletionStage<T> completionStage) {
-		return DefaultEntityResponseBuilder.fromCompletionStage(completionStage);
+	static <T> Builder<T> fromObject(T t, ParameterizedTypeReference<T> entityType) {
+		return DefaultEntityResponseBuilder.fromObject(t, entityType);
 	}
 
-	/**
-	 * Create a builder for an asynchronous body supplied by the given {@link Publisher}.
-	 * @param publisher the supplier of the response body
-	 * @param <T> the type of the elements contained in the publisher
-	 * @return the created builder
-	 */
-	static <T> Builder<Publisher<T>> fromPublisher(Publisher<T> publisher) {
-		return DefaultEntityResponseBuilder.fromPublisher(publisher);
-	}
 
 	/**
 	 * Defines a builder for {@code EntityResponse}.

spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerResponse.java

@@ -34,6 +34,7 @@ import javax.servlet.http.HttpServletResponse;
 
 import org.reactivestreams.Publisher;
 
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -362,26 +363,23 @@ public interface ServerResponse {
 
 		/**
 		 * Set the body of the response to the given {@code Object} and return it.
+		 *
+		 * <p>Asynchronous response bodies are supported by providing a {@link CompletionStage} or
+		 * {@link Publisher} as body.
 		 * @param body the body of the response
 		 * @return the built response
 		 */
 		ServerResponse body(Object body);
 
 		/**
-		 * Set the asynchronous body of the response to the given {@link CompletionStage} and
-		 * return it.
-		 * @param asyncBody the body of the response
-		 * @return the built response
-		 */
-		ServerResponse asyncBody(CompletionStage<?> asyncBody);
-
-		/**
-		 * Set the asynchronous body of the response to the given {@link Publisher} and
-		 * return it.
-		 * @param asyncBody the body of the response
+		 * Set the body of the response to the given {@code Object} and return it. The parameter
+		 * {@code bodyType} is used to capture the generic type.
+		 *
+		 * @param body the body of the response
+		 * @param bodyType the type of the body, used to capture the generic type
 		 * @return the built response
 		 */
-		ServerResponse asyncBody(Publisher<?> asyncBody);
+		<T> ServerResponse body(T body, ParameterizedTypeReference<T> bodyType);
 
 		/**
 		 * Render the template with the given {@code name} using the given {@code modelAttributes}.

spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultEntityResponseBuilderTests.java

@@ -29,6 +29,7 @@ import javax.servlet.http.Cookie;
 
 import org.junit.Test;
 
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -63,6 +64,16 @@ public class DefaultEntityResponseBuilderTests {
 		assertSame(body, response.entity());
 	}
 
+	@Test
+	public void fromObjectTypeReference() {
+		String body = "foo";
+		EntityResponse<String> response = EntityResponse.fromObject(body,
+				new ParameterizedTypeReference<String>() {})
+				.build();
+
+		assertSame(body, response.entity());
+	}
+
 	@Test
 	public void status() {
 		String body = "foo";

spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerRequestTests.java

@@ -36,6 +36,7 @@ import org.springframework.http.HttpRange;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
+import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.mock.web.test.MockHttpServletRequest;
 import org.springframework.mock.web.test.MockHttpSession;
 import org.springframework.util.LinkedMultiValueMap;
@@ -240,14 +241,16 @@ public class DefaultServerRequestTests {
 	@Test
 	public void bodyParameterizedTypeReference() throws Exception {
 		MockHttpServletRequest servletRequest = new MockHttpServletRequest("GET", "/");
-		servletRequest.setContentType(MediaType.TEXT_PLAIN_VALUE);
-		servletRequest.setContent("foo".getBytes(UTF_8));
+		servletRequest.setContentType(MediaType.APPLICATION_JSON_VALUE);
+		servletRequest.setContent("[\"foo\",\"bar\"]".getBytes(UTF_8));
 
 		DefaultServerRequest request = new DefaultServerRequest(servletRequest,
-				this.messageConverters);
+				Collections.singletonList(new MappingJackson2HttpMessageConverter()));
 
-		String result = request.body(new ParameterizedTypeReference<String>() {});
-		assertEquals("foo", result);
+		List<String> result = request.body(new ParameterizedTypeReference<List<String>>() {});
+		assertEquals(2, result.size());
+		assertEquals("foo", result.get(0));
+		assertEquals("bar", result.get(1));
 	}
 
 	@Test(expected = HttpMediaTypeNotSupportedException.class)

spring-webmvc/src/test/java/org/springframework/web/servlet/function/DefaultServerResponseBuilderTests.java

@@ -20,6 +20,7 @@ import java.net.URI;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.ChronoUnit;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
@@ -31,6 +32,7 @@ import org.junit.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Mono;
 
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -38,6 +40,7 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
+import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.mock.web.test.MockHttpServletRequest;
 import org.springframework.mock.web.test.MockHttpServletResponse;
 import org.springframework.util.LinkedMultiValueMap;
@@ -288,10 +291,27 @@ public class DefaultServerResponseBuilderTests {
 	}
 
 	@Test
-	public void asyncBodyCompletionStage() throws Exception {
+	public void bodyWithParameterizedTypeReference() throws Exception {
+		List<String> body = new ArrayList<>();
+		body.add("foo");
+		body.add("bar");
+		ServerResponse response = ServerResponse.ok().body(body, new ParameterizedTypeReference<List<String>>() {});
+
+		MockHttpServletRequest mockRequest = new MockHttpServletRequest("GET", "http://example.com");
+		MockHttpServletResponse mockResponse = new MockHttpServletResponse();
+		ServerResponse.Context context = () -> Collections.singletonList(new MappingJackson2HttpMessageConverter());
+
+		ModelAndView mav = response.writeTo(mockRequest, mockResponse, context);
+		assertNull(mav);
+
+		assertEquals("[\"foo\",\"bar\"]", mockResponse.getContentAsString());
+	}
+
+	@Test
+	public void bodyCompletionStage() throws Exception {
 		String body = "foo";
 		CompletionStage<String> completionStage = CompletableFuture.completedFuture(body);
-		ServerResponse response = ServerResponse.ok().asyncBody(completionStage);
+		ServerResponse response = ServerResponse.ok().body(completionStage);
 
 		MockHttpServletRequest mockRequest = new MockHttpServletRequest("GET", "http://example.com");
 		MockHttpServletResponse mockResponse = new MockHttpServletResponse();
@@ -307,10 +327,10 @@ public class DefaultServerResponseBuilderTests {
 	}
 
 	@Test
-	public void asyncBodyPublisher() throws Exception {
+	public void bodyPublisher() throws Exception {
 		String body = "foo";
 		Publisher<String> publisher = Mono.just(body);
-		ServerResponse response = ServerResponse.ok().asyncBody(publisher);
+		ServerResponse response = ServerResponse.ok().body(publisher);
 
 		MockHttpServletRequest mockRequest = new MockHttpServletRequest("GET", "http://example.com");
 		MockHttpServletResponse mockResponse = new MockHttpServletResponse();