From 1404dd768fd02391233d69519459df32581347fc Mon Sep 17 00:00:00 2001
From: Rossen Stoyanchev <rstoyanchev@vmware.com>
Date: Fri, 25 Sep 2020 13:57:30 +0100
Subject: [PATCH] Add exchangeToMono and exchangeToFlux + deprecate exchange()

See gh-25751
---
 .../function/client/ClientResponse.java       |  24 ----
 .../function/client/DefaultWebClient.java     | 110 +++++++++++-------
 .../reactive/function/client/WebClient.java   |  97 +++++++++++++--
 .../function/client/WebClientExtensions.kt    |   3 +-
 .../function/MultipartIntegrationTests.java   |  16 +--
 .../client/DefaultWebClientTests.java         |  39 ++++---
 .../WebClientDataBufferAllocatingTests.java   |   7 +-
 .../client/WebClientIntegrationTests.java     |  45 +++----
 ...LocaleContextResolverIntegrationTests.java |  14 +--
 .../annotation/MultipartIntegrationTests.java |  11 +-
 .../annotation/ProtobufIntegrationTests.java  |  52 +++++----
 ...LocaleContextResolverIntegrationTests.java |  15 +--
 12 files changed, 260 insertions(+), 173 deletions(-)

diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientResponse.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientResponse.java
index 1cb8790d37..897a1a28b5 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientResponse.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientResponse.java
@@ -45,30 +45,6 @@ import org.springframework.web.reactive.function.BodyExtractor;
  * {@link ExchangeFunction}. Provides access to the response status and
  * headers, and also methods to consume the response body.
  *
- * <p><strong>NOTE:</strong> When using a {@link ClientResponse}
- * through the {@code WebClient}
- * {@link WebClient.RequestHeadersSpec#exchange() exchange()} method,
- * you have to make sure that the body is consumed or released by using
- * one of the following methods:
- * <ul>
- * <li>{@link #body(BodyExtractor)}</li>
- * <li>{@link #bodyToMono(Class)} or
- *     {@link #bodyToMono(ParameterizedTypeReference)}</li>
- * <li>{@link #bodyToFlux(Class)} or
- *     {@link #bodyToFlux(ParameterizedTypeReference)}</li>
- * <li>{@link #toEntity(Class)} or
- *     {@link #toEntity(ParameterizedTypeReference)}</li>
- * <li>{@link #toEntityList(Class)} or
- *     {@link #toEntityList(ParameterizedTypeReference)}</li>
-*  <li>{@link #toBodilessEntity()}</li>
- * <li>{@link #releaseBody()}</li>
- * </ul>
- * You can also use {@code bodyToMono(Void.class)} if no response content is
- * expected. However keep in mind the connection will be closed, instead of
- * being placed back in the pool, if any content does arrive. This is in
- * contrast to {@link #releaseBody()} which does consume the full body and
- * releases any content received.
- *
  * @author Brian Clozel
  * @author Arjen Poutsma
  * @since 5.0
diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java
index b7f7e4fb0f..b8c849c29a 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java
@@ -147,6 +147,14 @@ class DefaultWebClient implements WebClient {
 		return new DefaultWebClientBuilder(this.builder);
 	}
 
+	private static Mono<Void> releaseIfNotConsumed(ClientResponse response) {
+		return response.releaseBody().onErrorResume(ex2 -> Mono.empty());
+	}
+
+	private static <T> Mono<T> releaseIfNotConsumed(ClientResponse response, Throwable ex) {
+		return response.releaseBody().onErrorResume(ex2 -> Mono.empty()).then(Mono.error(ex));
+	}
+
 
 	private class DefaultRequestBodyUriSpec implements RequestBodyUriSpec {
 
@@ -342,6 +350,65 @@ class DefaultWebClient implements WebClient {
 		}
 
 		@Override
+		public ResponseSpec retrieve() {
+			return new DefaultResponseSpec(exchange(), this::createRequest);
+		}
+
+		private HttpRequest createRequest() {
+			return new HttpRequest() {
+				private final URI uri = initUri();
+				private final HttpHeaders headers = initHeaders();
+
+				@Override
+				public HttpMethod getMethod() {
+					return httpMethod;
+				}
+				@Override
+				public String getMethodValue() {
+					return httpMethod.name();
+				}
+				@Override
+				public URI getURI() {
+					return this.uri;
+				}
+				@Override
+				public HttpHeaders getHeaders() {
+					return this.headers;
+				}
+			};
+		}
+
+		@Override
+		public <V> Mono<V> exchangeToMono(Function<ClientResponse, ? extends Mono<V>> responseHandler) {
+			return exchange().flatMap(response -> {
+				try {
+					return responseHandler.apply(response)
+							.flatMap(value -> releaseIfNotConsumed(response).thenReturn(value))
+							.switchIfEmpty(Mono.defer(() -> releaseIfNotConsumed(response).then(Mono.empty())))
+							.onErrorResume(ex -> releaseIfNotConsumed(response, ex));
+				}
+				catch (Throwable ex) {
+					return releaseIfNotConsumed(response, ex);
+				}
+			});
+		}
+
+		@Override
+		public <V> Flux<V> exchangeToFlux(Function<ClientResponse, ? extends Flux<V>> responseHandler) {
+			return exchange().flatMapMany(response -> {
+				try {
+					return responseHandler.apply(response)
+							.concatWith(Flux.defer(() -> releaseIfNotConsumed(response).then(Mono.empty())))
+							.onErrorResume(ex -> releaseIfNotConsumed(response, ex));
+				}
+				catch (Throwable ex) {
+					return releaseIfNotConsumed(response, ex);
+				}
+			});
+		}
+
+		@Override
+		@SuppressWarnings("deprecation")
 		public Mono<ClientResponse> exchange() {
 			ClientRequest request = (this.inserter != null ?
 					initRequestBuilder().body(this.inserter).build() :
@@ -398,35 +465,6 @@ class DefaultWebClient implements WebClient {
 				return result;
 			}
 		}
-
-		@Override
-		public ResponseSpec retrieve() {
-			return new DefaultResponseSpec(exchange(), this::createRequest);
-		}
-
-		private HttpRequest createRequest() {
-			return new HttpRequest() {
-				private final URI uri = initUri();
-				private final HttpHeaders headers = initHeaders();
-
-				@Override
-				public HttpMethod getMethod() {
-					return httpMethod;
-				}
-				@Override
-				public String getMethodValue() {
-					return httpMethod.name();
-				}
-				@Override
-				public URI getURI() {
-					return this.uri;
-				}
-				@Override
-				public HttpHeaders getHeaders() {
-					return this.headers;
-				}
-			};
-		}
 	}
 
 
@@ -530,11 +568,11 @@ class DefaultWebClient implements WebClient {
 					Mono<? extends Throwable> exMono;
 					try {
 						exMono = handler.apply(response);
-						exMono = exMono.flatMap(ex -> drainBody(response, ex));
-						exMono = exMono.onErrorResume(ex -> drainBody(response, ex));
+						exMono = exMono.flatMap(ex -> releaseIfNotConsumed(response, ex));
+						exMono = exMono.onErrorResume(ex -> releaseIfNotConsumed(response, ex));
 					}
 					catch (Throwable ex2) {
-						exMono = drainBody(response, ex2);
+						exMono = releaseIfNotConsumed(response, ex2);
 					}
 					Mono<T> result = exMono.flatMap(Mono::error);
 					HttpRequest request = this.requestSupplier.get();
@@ -544,14 +582,6 @@ class DefaultWebClient implements WebClient {
 			return null;
 		}
 
-		@SuppressWarnings("unchecked")
-		private <T> Mono<T> drainBody(ClientResponse response, Throwable ex) {
-			// Ensure the body is drained, even if the StatusHandler didn't consume it,
-			// but ignore exception, in case the handler did consume.
-			return (Mono<T>) response.releaseBody()
-					.onErrorResume(ex2 -> Mono.empty()).thenReturn(ex);
-		}
-
 		private <T> Mono<T> insertCheckpoint(Mono<T> result, int statusCode, HttpRequest request) {
 			String httpMethod = request.getMethodValue();
 			URI uri = request.getURI();
diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java
index c7843a2d99..adc044752f 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java
@@ -57,7 +57,8 @@ import org.springframework.web.util.UriBuilderFactory;
  * <p>For examples with a response body see:
  * <ul>
  * <li>{@link RequestHeadersSpec#retrieve() retrieve()}
- * <li>{@link RequestHeadersSpec#exchange() exchange()}
+ * <li>{@link RequestHeadersSpec#exchangeToMono(Function) exchangeToMono()}
+ * <li>{@link RequestHeadersSpec#exchangeToFlux(Function) exchangeToFlux()}
  * </ul>
  * <p>For examples with a request body see:
  * <ul>
@@ -252,8 +253,7 @@ public interface WebClient {
 		Builder defaultCookies(Consumer<MultiValueMap<String, String>> cookiesConsumer);
 
 		/**
-		 * Provide a consumer to modify every request being built just before the
-		 * call to {@link RequestHeadersSpec#exchange() exchange()}.
+		 * Provide a consumer to customize every request being built.
 		 * @param defaultRequest the consumer to use for modifying requests
 		 * @since 5.1
 		 */
@@ -483,21 +483,93 @@ public interface WebClient {
 		S httpRequest(Consumer<ClientHttpRequest> requestConsumer);
 
 		/**
-		 * Perform the HTTP request and retrieve the response body:
+		 * Proceed to declare how to extract the response. For example to extract
+		 * a {@link ResponseEntity} with status, headers, and body:
 		 * <p><pre>
-		 * Mono&lt;Person&gt; bodyMono = client.get()
+		 * Mono&lt;ResponseEntity&lt;Person&gt;&gt; entityMono = client.get()
+		 *     .uri("/persons/1")
+		 *     .accept(MediaType.APPLICATION_JSON)
+		 *     .retrieve()
+		 *     .toEntity(Person.class);
+		 * </pre>
+		 * <p>Or if interested only in the body:
+		 * <p><pre>
+		 * Mono&lt;Person&gt; entityMono = client.get()
 		 *     .uri("/persons/1")
 		 *     .accept(MediaType.APPLICATION_JSON)
 		 *     .retrieve()
 		 *     .bodyToMono(Person.class);
 		 * </pre>
-		 * <p>This method is a shortcut to using {@link #exchange()} and
-		 * decoding the response body through {@link ClientResponse}.
-		 * @return {@code ResponseSpec} to specify how to decode the body
-		 * @see #exchange()
+		 * <p>By default, 4xx and 5xx responses result in a
+		 * {@link WebClientResponseException}. To customize error handling, use
+		 * {@link ResponseSpec#onStatus(Predicate, Function) onStatus} handlers.
 		 */
 		ResponseSpec retrieve();
 
+		/**
+		 * An alternative to {@link #retrieve()} that provides more control via
+		 * access to the {@link ClientResponse}. This can be useful for advanced
+		 * scenarios, for example to decode the response differently depending
+		 * on the response status:
+		 * <p><pre>
+		 * Mono&lt;Object&gt; entityMono = client.get()
+		 *     .uri("/persons/1")
+		 *     .accept(MediaType.APPLICATION_JSON)
+		 *     .exchangeToMono(response -> {
+		 *         if (response.statusCode().equals(HttpStatus.OK)) {
+		 *             return response.bodyToMono(Person.class);
+		 *         }
+		 *         else if (response.statusCode().is4xxClientError()) {
+		 *             return response.bodyToMono(ErrorContainer.class);
+		 *         }
+		 *         else {
+		 *             return Mono.error(response.createException());
+		 *         }
+		 *     });
+		 * </pre>
+		 * <p><strong>Note:</strong> After the returned {@code Mono} completes,
+		 * the response body is automatically released if it hasn't been consumed.
+		 * If the response content is needed, the provided function must declare
+		 * how to decode it.
+		 * @param responseHandler the function to handle the response with
+		 * @param <V> the type of Object the response will be transformed to
+		 * @return a {@code Mono} produced from the response
+		 * @since 5.3
+		 */
+		<V> Mono<V> exchangeToMono(Function<ClientResponse, ? extends Mono<V>> responseHandler);
+
+		/**
+		 * An alternative to {@link #retrieve()} that provides more control via
+		 * access to the {@link ClientResponse}. This can be useful for advanced
+		 * scenarios, for example to decode the response differently depending
+		 * on the response status:
+		 * <p><pre>
+		 * Mono&lt;Object&gt; entityMono = client.get()
+		 *     .uri("/persons")
+		 *     .accept(MediaType.APPLICATION_JSON)
+		 *     .exchangeToFlux(response -> {
+		 *         if (response.statusCode().equals(HttpStatus.OK)) {
+		 *             return response.bodyToFlux(Person.class);
+		 *         }
+		 *         else if (response.statusCode().is4xxClientError()) {
+		 *             return response.bodyToMono(ErrorContainer.class).flux();
+		 *         }
+		 *         else {
+		 *             return Flux.error(response.createException());
+		 *         }
+		 *     });
+		 * </pre>
+		 * <p><strong>Note:</strong> After the returned {@code Flux} completes,
+		 * the response body is automatically released if it hasn't been consumed.
+		 * If the response content is needed, the provided function must declare
+		 * how to decode it.
+		 * @param responseHandler the function to handle the response with
+		 * @param <V> the type of Objects the response will be transformed to
+		 * @return a {@code Flux} of Objects produced from the response
+		 * @since 5.3
+		 */
+		<V> Flux<V> exchangeToFlux(Function<ClientResponse, ? extends Flux<V>> responseHandler);
+
 		/**
 		 * Perform the HTTP request and return a {@link ClientResponse} with the
 		 * response status and headers. You can then use methods of the response
@@ -526,7 +598,14 @@ public interface WebClient {
 		 * if to consume the response.
 		 * @return a {@code Mono} for the response
 		 * @see #retrieve()
+		 * @deprecated since 5.3 due to the possibility to leak memory and/or
+		 * connections; please, use {@link #exchangeToMono(Function)},
+		 * {@link #exchangeToFlux(Function)}; consider also using
+		 * {@link #retrieve()} which provides access to the response status
+		 * and headers via {@link ResponseEntity} along with error status
+		 * handling.
 		 */
+		@Deprecated
 		Mono<ClientResponse> exchange();
 	}
 
diff --git a/spring-webflux/src/main/kotlin/org/springframework/web/reactive/function/client/WebClientExtensions.kt b/spring-webflux/src/main/kotlin/org/springframework/web/reactive/function/client/WebClientExtensions.kt
index 486cfb0beb..ec1d10a740 100644
--- a/spring-webflux/src/main/kotlin/org/springframework/web/reactive/function/client/WebClientExtensions.kt
+++ b/spring-webflux/src/main/kotlin/org/springframework/web/reactive/function/client/WebClientExtensions.kt
@@ -17,8 +17,8 @@
 package org.springframework.web.reactive.function.client
 
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.reactive.awaitSingle
 import kotlinx.coroutines.reactive.asFlow
+import kotlinx.coroutines.reactive.awaitSingle
 import org.reactivestreams.Publisher
 import org.springframework.core.ParameterizedTypeReference
 import org.springframework.web.reactive.function.client.WebClient.RequestBodySpec
@@ -69,6 +69,7 @@ inline fun <reified T : Any> RequestBodySpec.body(producer: Any): RequestHeaders
  * @author Sebastien Deleuze
  * @since 5.2
  */
+@Suppress("DEPRECATION")
 suspend fun RequestHeadersSpec<out RequestHeadersSpec<*>>.awaitExchange(): ClientResponse =
 		exchange().awaitSingle()
 
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/MultipartIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/MultipartIntegrationTests.java
index 0441d3fe7c..a1f28b1b63 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/MultipartIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/MultipartIntegrationTests.java
@@ -29,13 +29,13 @@ import reactor.test.StepVerifier;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.MultipartBodyBuilder;
 import org.springframework.http.codec.multipart.FilePart;
 import org.springframework.http.codec.multipart.FormFieldPart;
 import org.springframework.http.codec.multipart.Part;
 import org.springframework.util.FileCopyUtils;
 import org.springframework.util.MultiValueMap;
-import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.function.server.AbstractRouterFunctionIntegrationTests;
 import org.springframework.web.reactive.function.server.RouterFunction;
@@ -62,15 +62,16 @@ class MultipartIntegrationTests extends AbstractRouterFunctionIntegrationTests {
 	void multipartData(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<ClientResponse> result = webClient
+		Mono<ResponseEntity<Void>> result = webClient
 				.post()
 				.uri("http://localhost:" + this.port + "/multipartData")
 				.bodyValue(generateBody())
-				.exchange();
+				.retrieve()
+				.toEntity(Void.class);
 
 		StepVerifier
 				.create(result)
-				.consumeNextWith(response -> assertThat(response.statusCode()).isEqualTo(HttpStatus.OK))
+				.consumeNextWith(entity -> assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK))
 				.verifyComplete();
 	}
 
@@ -78,15 +79,16 @@ class MultipartIntegrationTests extends AbstractRouterFunctionIntegrationTests {
 	void parts(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<ClientResponse> result = webClient
+		Mono<ResponseEntity<Void>> result = webClient
 				.post()
 				.uri("http://localhost:" + this.port + "/parts")
 				.bodyValue(generateBody())
-				.exchange();
+				.retrieve()
+				.toEntity(Void.class);
 
 		StepVerifier
 				.create(result)
-				.consumeNextWith(response -> assertThat(response.statusCode()).isEqualTo(HttpStatus.OK))
+				.consumeNextWith(entity -> assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK))
 				.verifyComplete();
 	}
 
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultWebClientTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultWebClientTests.java
index a40f386d41..e5f2df9e25 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultWebClientTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultWebClientTests.java
@@ -47,6 +47,7 @@ import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
 
 /**
  * Unit tests for {@link DefaultWebClient}.
@@ -69,6 +70,7 @@ public class DefaultWebClientTests {
 	@BeforeEach
 	public void setup() {
 		ClientResponse mockResponse = mock(ClientResponse.class);
+		when(mockResponse.bodyToMono(Void.class)).thenReturn(Mono.empty());
 		given(this.exchangeFunction.exchange(this.captor.capture())).willReturn(Mono.just(mockResponse));
 		this.builder = WebClient.builder().baseUrl("/base").exchangeFunction(this.exchangeFunction);
 	}
@@ -77,7 +79,7 @@ public class DefaultWebClientTests {
 	@Test
 	public void basic() {
 		this.builder.build().get().uri("/path")
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.url().toString()).isEqualTo("/base/path");
@@ -89,7 +91,7 @@ public class DefaultWebClientTests {
 	public void uriBuilder() {
 		this.builder.build().get()
 				.uri(builder -> builder.path("/path").queryParam("q", "12").build())
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.url().toString()).isEqualTo("/base/path?q=12");
@@ -98,8 +100,8 @@ public class DefaultWebClientTests {
 	@Test // gh-22705
 	public void uriBuilderWithUriTemplate() {
 		this.builder.build().get()
-					.uri("/path/{id}", builder -> builder.queryParam("q", "12").build("identifier"))
-					.exchange().block(Duration.ofSeconds(10));
+				.uri("/path/{id}", builder -> builder.queryParam("q", "12").build("identifier"))
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.url().toString()).isEqualTo("/base/path/identifier?q=12");
@@ -110,7 +112,7 @@ public class DefaultWebClientTests {
 	public void uriBuilderWithPathOverride() {
 		this.builder.build().get()
 				.uri(builder -> builder.replacePath("/path").build())
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.url().toString()).isEqualTo("/path");
@@ -120,7 +122,7 @@ public class DefaultWebClientTests {
 	public void requestHeaderAndCookie() {
 		this.builder.build().get().uri("/path").accept(MediaType.APPLICATION_JSON)
 				.cookies(cookies -> cookies.add("id", "123"))	// SPR-16178
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.headers().getFirst("Accept")).isEqualTo("application/json");
@@ -131,7 +133,7 @@ public class DefaultWebClientTests {
 	public void httpRequest() {
 		this.builder.build().get().uri("/path")
 				.httpRequest(httpRequest -> {})
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.httpRequest()).isNotNull();
@@ -143,7 +145,8 @@ public class DefaultWebClientTests {
 				.defaultHeader("Accept", "application/json").defaultCookie("id", "123")
 				.build();
 
-		client.get().uri("/path").exchange().block(Duration.ofSeconds(10));
+		client.get().uri("/path")
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.headers().getFirst("Accept")).isEqualTo("application/json");
@@ -160,7 +163,7 @@ public class DefaultWebClientTests {
 		client.get().uri("/path")
 				.header("Accept", "application/xml")
 				.cookie("id", "456")
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.headers().getFirst("Accept")).isEqualTo("application/xml");
@@ -185,7 +188,7 @@ public class DefaultWebClientTests {
 		try {
 			context.set("bar");
 			client.get().uri("/path").attribute("foo", "bar")
-					.exchange().block(Duration.ofSeconds(10));
+					.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 		}
 		finally {
 			context.remove();
@@ -271,7 +274,7 @@ public class DefaultWebClientTests {
 		this.builder.filter(filter).build()
 				.get().uri("/path")
 				.attribute("foo", "bar")
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		assertThat(actual.get("foo")).isEqualTo("bar");
 
@@ -290,7 +293,7 @@ public class DefaultWebClientTests {
 		this.builder.filter(filter).build()
 				.get().uri("/path")
 				.attribute("foo", null)
-				.exchange().block(Duration.ofSeconds(10));
+				.retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		assertThat(actual.get("foo")).isNull();
 
@@ -306,7 +309,7 @@ public class DefaultWebClientTests {
 						.defaultCookie("id", "123"))
 				.build();
 
-		client.get().uri("/path").exchange().block(Duration.ofSeconds(10));
+		client.get().uri("/path").retrieve().bodyToMono(Void.class).block(Duration.ofSeconds(10));
 
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.headers().getFirst("Accept")).isEqualTo("application/json");
@@ -317,8 +320,8 @@ public class DefaultWebClientTests {
 	public void switchToErrorOnEmptyClientResponseMono() {
 		ExchangeFunction exchangeFunction = mock(ExchangeFunction.class);
 		given(exchangeFunction.exchange(any())).willReturn(Mono.empty());
-		WebClient.Builder builder = WebClient.builder().baseUrl("/base").exchangeFunction(exchangeFunction);
-		StepVerifier.create(builder.build().get().uri("/path").exchange())
+		WebClient client = WebClient.builder().baseUrl("/base").exchangeFunction(exchangeFunction).build();
+		StepVerifier.create(client.get().uri("/path").retrieve().bodyToMono(Void.class))
 				.expectErrorMessage("The underlying HTTP client completed without emitting a response.")
 				.verify(Duration.ofSeconds(5));
 	}
@@ -333,9 +336,11 @@ public class DefaultWebClientTests {
 							.build())
 				)
 				.build();
-		Mono<ClientResponse> exchange = client.get().uri("/path").exchange();
+
+		Mono<Void> result = client.get().uri("/path").retrieve().bodyToMono(Void.class);
+
 		verifyNoInteractions(this.exchangeFunction);
-		exchange.block(Duration.ofSeconds(10));
+		result.block(Duration.ofSeconds(10));
 		ClientRequest request = verifyAndGetRequest();
 		assertThat(request.headers().getFirst("Custom")).isEqualTo("value");
 	}
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientDataBufferAllocatingTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientDataBufferAllocatingTests.java
index 4b5ec631b9..33202d48f4 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientDataBufferAllocatingTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientDataBufferAllocatingTests.java
@@ -182,9 +182,7 @@ class WebClientDataBufferAllocatingTests extends AbstractDataBufferAllocatingTes
 				.setBody("foo bar"));
 
 		Mono<Void> result  = this.webClient.get()
-				.exchange()
-				.flatMap(ClientResponse::releaseBody);
-
+				.exchangeToMono(ClientResponse::releaseBody);
 
 		StepVerifier.create(result)
 				.expectComplete()
@@ -201,8 +199,7 @@ class WebClientDataBufferAllocatingTests extends AbstractDataBufferAllocatingTes
 				.setBody("foo bar"));
 
 		Mono<ResponseEntity<Void>> result  = this.webClient.get()
-				.exchange()
-				.flatMap(ClientResponse::toBodilessEntity);
+				.exchangeToMono(ClientResponse::toBodilessEntity);
 
 		StepVerifier.create(result)
 				.assertNext(entity -> {
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
index 50a9b9f65b..5c61261fb2 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java
@@ -837,8 +837,7 @@ class WebClientIntegrationTests {
 		Mono<String> result = this.webClient.get()
 				.uri("/greeting")
 				.header("X-Test-Header", "testvalue")
-				.exchange()
-				.flatMap(response -> response.bodyToMono(String.class));
+				.retrieve().bodyToMono(String.class);
 
 		StepVerifier.create(result)
 				.expectNext("Hello Spring!")
@@ -862,8 +861,7 @@ class WebClientIntegrationTests {
 
 		Mono<ResponseEntity<Pojo>> result = this.webClient.get()
 				.uri("/json").accept(MediaType.APPLICATION_JSON)
-				.exchange()
-				.flatMap(response -> response.toEntity(Pojo.class));
+				.retrieve().toEntity(Pojo.class);
 
 		StepVerifier.create(result)
 				.consumeNextWith(entity -> {
@@ -890,8 +888,7 @@ class WebClientIntegrationTests {
 
 		Mono<ResponseEntity<Void>> result = this.webClient.get()
 				.uri("/json").accept(MediaType.APPLICATION_JSON)
-				.exchange()
-				.flatMap(ClientResponse::toBodilessEntity);
+				.retrieve().toBodilessEntity();
 
 		StepVerifier.create(result)
 				.consumeNextWith(entity -> {
@@ -919,8 +916,7 @@ class WebClientIntegrationTests {
 
 		Mono<ResponseEntity<List<Pojo>>> result = this.webClient.get()
 				.uri("/json").accept(MediaType.APPLICATION_JSON)
-				.exchange()
-				.flatMap(response -> response.toEntityList(Pojo.class));
+				.retrieve().toEntityList(Pojo.class);
 
 		StepVerifier.create(result)
 				.consumeNextWith(entity -> {
@@ -948,8 +944,7 @@ class WebClientIntegrationTests {
 
 		Mono<ResponseEntity<Void>> result = this.webClient.get()
 				.uri("/noContent")
-				.exchange()
-				.flatMap(response -> response.toEntity(Void.class));
+				.retrieve().toBodilessEntity();
 
 		StepVerifier.create(result)
 				.assertNext(r -> assertThat(r.getStatusCode().is2xxSuccessful()).isTrue())
@@ -963,10 +958,11 @@ class WebClientIntegrationTests {
 		prepareResponse(response -> response.setResponseCode(404)
 				.setHeader("Content-Type", "text/plain").setBody("Not Found"));
 
-		Mono<ClientResponse> result = this.webClient.get().uri("/greeting").exchange();
+		Mono<ResponseEntity<Void>> result = this.webClient.get().uri("/greeting")
+				.exchangeToMono(ClientResponse::toBodilessEntity);
 
 		StepVerifier.create(result)
-				.consumeNextWith(response -> assertThat(response.statusCode()).isEqualTo(HttpStatus.NOT_FOUND))
+				.consumeNextWith(entity -> assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.NOT_FOUND))
 				.expectComplete()
 				.verify(Duration.ofSeconds(3));
 
@@ -987,12 +983,12 @@ class WebClientIntegrationTests {
 		prepareResponse(response -> response.setResponseCode(errorStatus)
 				.setHeader("Content-Type", "text/plain").setBody(errorMessage));
 
-		Mono<ClientResponse> result = this.webClient.get()
+		Mono<ResponseEntity<Void>> result = this.webClient.get()
 				.uri("/unknownPage")
-				.exchange();
+				.exchangeToMono(ClientResponse::toBodilessEntity);
 
 		StepVerifier.create(result)
-				.consumeNextWith(response -> assertThat(response.rawStatusCode()).isEqualTo(555))
+				.consumeNextWith(entity -> assertThat(entity.getStatusCodeValue()).isEqualTo(555))
 				.expectComplete()
 				.verify(Duration.ofSeconds(3));
 
@@ -1008,7 +1004,8 @@ class WebClientIntegrationTests {
 		startServer(connector);
 
 		String uri = "/api/v4/groups/1";
-		Mono<ClientResponse> responseMono = WebClient.builder().build().get().uri(uri).exchange();
+		Mono<ResponseEntity<Void>> responseMono = WebClient.builder().build().get().uri(uri)
+				.retrieve().toBodilessEntity();
 
 		StepVerifier.create(responseMono)
 				.expectErrorSatisfies(throwable -> {
@@ -1103,12 +1100,9 @@ class WebClientIntegrationTests {
 				.addHeader("Set-Cookie", "testkey2=testvalue2; Max-Age=42; HttpOnly; SameSite=Lax; Secure")
 				.setBody("test"));
 
-		Mono<ClientResponse> result = this.webClient.get()
+		this.webClient.get()
 				.uri("/test")
-				.exchange();
-
-		StepVerifier.create(result)
-				.consumeNextWith(response -> {
+				.exchangeToMono(response -> {
 					assertThat(response.cookies()).containsOnlyKeys("testkey1", "testkey2");
 
 					ResponseCookie cookie1 = response.cookies().get("testkey1").get(0);
@@ -1123,9 +1117,10 @@ class WebClientIntegrationTests {
 					assertThat(cookie2.isHttpOnly()).isTrue();
 					assertThat(cookie2.getSameSite()).isEqualTo("Lax");
 					assertThat(cookie2.getMaxAge().getSeconds()).isEqualTo(42);
+
+					return response.releaseBody();
 				})
-				.expectComplete()
-				.verify(Duration.ofSeconds(3));
+				.block(Duration.ofSeconds(3));
 
 		expectRequestCount(1);
 	}
@@ -1135,9 +1130,7 @@ class WebClientIntegrationTests {
 		startServer(connector);
 
 		String url = "http://example.invalid";
-		Mono<ClientResponse> result = this.webClient.get().
-				uri(url)
-				.exchange();
+		Mono<Void> result = this.webClient.get().uri(url).retrieve().bodyToMono(Void.class);
 
 		StepVerifier.create(result)
 				.expectErrorSatisfies(throwable -> {
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/function/server/LocaleContextResolverIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/function/server/LocaleContextResolverIntegrationTests.java
index efc8cf8c1e..b5a4e2bd4e 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/function/server/LocaleContextResolverIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/function/server/LocaleContextResolverIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -26,8 +26,8 @@ import reactor.test.StepVerifier;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
 import org.springframework.lang.Nullable;
-import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.result.view.View;
 import org.springframework.web.reactive.result.view.ViewResolver;
@@ -66,16 +66,16 @@ class LocaleContextResolverIntegrationTests extends AbstractRouterFunctionIntegr
 	void fixedLocale(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<ClientResponse> result = webClient
+		Mono<ResponseEntity<Void>> result = webClient
 				.get()
 				.uri("http://localhost:" + this.port + "/")
-				.exchange();
+				.retrieve().toBodilessEntity();
 
 		StepVerifier
 				.create(result)
-				.consumeNextWith(response -> {
-					assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
-					assertThat(response.headers().asHttpHeaders().getContentLanguage()).isEqualTo(Locale.GERMANY);
+				.consumeNextWith(entity -> {
+					assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
+					assertThat(entity.getHeaders().getContentLanguage()).isEqualTo(Locale.GERMANY);
 				})
 				.verifyComplete();
 	}
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MultipartIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MultipartIntegrationTests.java
index 34558d112b..1b49442ce2 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MultipartIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MultipartIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -37,6 +37,7 @@ import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.MultipartBodyBuilder;
 import org.springframework.http.codec.multipart.FilePart;
 import org.springframework.http.codec.multipart.FormFieldPart;
@@ -52,7 +53,6 @@ import org.springframework.web.bind.annotation.RequestPart;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.reactive.DispatcherHandler;
 import org.springframework.web.reactive.config.EnableWebFlux;
-import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
 import org.springframework.web.testfixture.http.server.reactive.bootstrap.AbstractHttpHandlerIntegrationTests;
@@ -85,15 +85,16 @@ class MultipartIntegrationTests extends AbstractHttpHandlerIntegrationTests {
 	void requestPart(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<ClientResponse> result = webClient
+		Mono<ResponseEntity<Void>> result = webClient
 				.post()
 				.uri("/requestPart")
 				.bodyValue(generateBody())
-				.exchange();
+				.retrieve()
+				.toBodilessEntity();
 
 		StepVerifier
 				.create(result)
-				.consumeNextWith(response -> assertThat(response.statusCode()).isEqualTo(HttpStatus.OK))
+				.consumeNextWith(entity -> assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK))
 				.verifyComplete();
 	}
 
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ProtobufIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ProtobufIntegrationTests.java
index e64264e837..f06955d7dc 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ProtobufIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ProtobufIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -17,6 +17,7 @@
 package org.springframework.web.reactive.result.method.annotation;
 
 import java.time.Duration;
+import java.util.List;
 
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -26,6 +27,8 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.reactive.config.EnableWebFlux;
@@ -66,18 +69,19 @@ class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationTests {
 	void value(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<Msg> result = this.webClient.get()
+		Mono<ResponseEntity<Msg>> result = this.webClient.get()
 				.uri("/message")
-				.exchange()
-				.doOnNext(response -> {
-					assertThat(response.headers().contentType().get().getParameters().containsKey("delimited")).isFalse();
-					assertThat(response.headers().header("X-Protobuf-Schema").get(0)).isEqualTo("sample.proto");
-					assertThat(response.headers().header("X-Protobuf-Message").get(0)).isEqualTo("Msg");
-				})
-				.flatMap(response -> response.bodyToMono(Msg.class));
+				.retrieve()
+				.toEntity(Msg.class);
 
 		StepVerifier.create(result)
-				.expectNext(TEST_MSG)
+				.consumeNextWith(entity -> {
+					HttpHeaders headers = entity.getHeaders();
+					assertThat(headers.getContentType().getParameters().containsKey("delimited")).isFalse();
+					assertThat(headers.getFirst("X-Protobuf-Schema")).isEqualTo("sample.proto");
+					assertThat(headers.getFirst("X-Protobuf-Message")).isEqualTo("Msg");
+					assertThat(entity.getBody()).isEqualTo(TEST_MSG);
+				})
 				.verifyComplete();
 	}
 
@@ -85,20 +89,19 @@ class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationTests {
 	void values(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Flux<Msg> result = this.webClient.get()
+		Mono<ResponseEntity<List<Msg>>> result = this.webClient.get()
 				.uri("/messages")
-				.exchange()
-				.doOnNext(response -> {
-					assertThat(response.headers().contentType().get().getParameters().get("delimited")).isEqualTo("true");
-					assertThat(response.headers().header("X-Protobuf-Schema").get(0)).isEqualTo("sample.proto");
-					assertThat(response.headers().header("X-Protobuf-Message").get(0)).isEqualTo("Msg");
-				})
-				.flatMapMany(response -> response.bodyToFlux(Msg.class));
+				.retrieve()
+				.toEntityList(Msg.class);
 
 		StepVerifier.create(result)
-				.expectNext(TEST_MSG)
-				.expectNext(TEST_MSG)
-				.expectNext(TEST_MSG)
+				.consumeNextWith(entity -> {
+					HttpHeaders headers = entity.getHeaders();
+					assertThat(headers.getContentType().getParameters().get("delimited")).isEqualTo("true");
+					assertThat(headers.getFirst("X-Protobuf-Schema")).isEqualTo("sample.proto");
+					assertThat(headers.getFirst("X-Protobuf-Message")).isEqualTo("Msg");
+					assertThat(entity.getBody()).containsExactly(TEST_MSG, TEST_MSG, TEST_MSG);
+				})
 				.verifyComplete();
 	}
 
@@ -108,13 +111,12 @@ class ProtobufIntegrationTests extends AbstractRequestMappingIntegrationTests {
 
 		Flux<Msg> result = this.webClient.get()
 				.uri("/message-stream")
-				.exchange()
-				.doOnNext(response -> {
+				.exchangeToFlux(response -> {
 					assertThat(response.headers().contentType().get().getParameters().get("delimited")).isEqualTo("true");
 					assertThat(response.headers().header("X-Protobuf-Schema").get(0)).isEqualTo("sample.proto");
 					assertThat(response.headers().header("X-Protobuf-Message").get(0)).isEqualTo("Msg");
-				})
-				.flatMapMany(response -> response.bodyToFlux(Msg.class));
+					return response.bodyToFlux(Msg.class);
+				});
 
 		StepVerifier.create(result)
 				.expectNext(Msg.newBuilder().setFoo("Foo").setBlah(SecondMsg.newBuilder().setBlah(0).build()).build())
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/LocaleContextResolverIntegrationTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/LocaleContextResolverIntegrationTests.java
index b21b68cd5b..bf0e326396 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/LocaleContextResolverIntegrationTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/LocaleContextResolverIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -30,12 +30,12 @@ import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
 import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.reactive.config.ViewResolverRegistry;
 import org.springframework.web.reactive.config.WebFluxConfigurationSupport;
-import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.result.method.annotation.AbstractRequestMappingIntegrationTests;
 import org.springframework.web.server.ServerWebExchange;
@@ -66,15 +66,16 @@ class LocaleContextResolverIntegrationTests extends AbstractRequestMappingIntegr
 	void fixedLocale(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		Mono<ClientResponse> result = webClient
+		Mono<ResponseEntity<Void>> result = webClient
 				.get()
 				.uri("http://localhost:" + this.port + "/")
-				.exchange();
+				.retrieve()
+				.toBodilessEntity();
 
 		StepVerifier.create(result)
-				.consumeNextWith(response -> {
-					assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
-					assertThat(response.headers().asHttpHeaders().getContentLanguage()).isEqualTo(Locale.GERMANY);
+				.consumeNextWith(entity -> {
+					assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
+					assertThat(entity.getHeaders().getContentLanguage()).isEqualTo(Locale.GERMANY);
 				})
 				.verifyComplete();
 	}