Merge branch '25751-exchange-deprecation' into master

Closes gh-25751

spring-test/src/main/java/org/springframework/test/web/reactive/server/DefaultWebTestClient.java

@@ -22,6 +22,7 @@ import java.nio.charset.StandardCharsets;
 import java.time.Duration;
 import java.time.ZonedDateTime;
 import java.util.Arrays;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -46,12 +47,17 @@ import org.springframework.test.util.AssertionErrors;
 import org.springframework.test.util.JsonExpectationsHelper;
 import org.springframework.test.util.XmlExpectationsHelper;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MimeType;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.reactive.function.BodyInserter;
+import org.springframework.web.reactive.function.BodyInserters;
+import org.springframework.web.reactive.function.client.ClientRequest;
 import org.springframework.web.reactive.function.client.ClientResponse;
-import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.client.ExchangeFunction;
 import org.springframework.web.util.UriBuilder;
+import org.springframework.web.util.UriBuilderFactory;
 
 /**
  * Default implementation of {@link WebTestClient}.
@@ -61,30 +67,42 @@ import org.springframework.web.util.UriBuilder;
  */
 class DefaultWebTestClient implements WebTestClient {
 
-	private final WebClient webClient;
-
 	private final WiretapConnector wiretapConnector;
 
-	private final Duration timeout;
+	private final ExchangeFunction exchangeFunction;
+
+	private final UriBuilderFactory uriBuilderFactory;
+
+	@Nullable
+	private final HttpHeaders defaultHeaders;
+
+	@Nullable
+	private final MultiValueMap<String, String> defaultCookies;
+
+	private final Duration responseTimeout;
 
 	private final DefaultWebTestClientBuilder builder;
 
 	private final AtomicLong requestIndex = new AtomicLong();
 
 
-	DefaultWebTestClient(WebClient.Builder clientBuilder, ClientHttpConnector connector,
-			@Nullable Duration timeout, DefaultWebTestClientBuilder webTestClientBuilder) {
+	DefaultWebTestClient(ClientHttpConnector connector,
+			Function<ClientHttpConnector, ExchangeFunction> exchangeFactory, UriBuilderFactory uriBuilderFactory,
+			@Nullable HttpHeaders headers, @Nullable MultiValueMap<String, String> cookies,
+			@Nullable Duration responseTimeout, DefaultWebTestClientBuilder clientBuilder) {
 
-		Assert.notNull(clientBuilder, "WebClient.Builder is required");
 		this.wiretapConnector = new WiretapConnector(connector);
-		this.webClient = clientBuilder.clientConnector(this.wiretapConnector).build();
-		this.timeout = (timeout != null ? timeout : Duration.ofSeconds(5));
-		this.builder = webTestClientBuilder;
+		this.exchangeFunction = exchangeFactory.apply(this.wiretapConnector);
+		this.uriBuilderFactory = uriBuilderFactory;
+		this.defaultHeaders = headers;
+		this.defaultCookies = cookies;
+		this.responseTimeout = (responseTimeout != null ? responseTimeout : Duration.ofSeconds(5));
+		this.builder = clientBuilder;
 	}
 
 
-	private Duration getTimeout() {
-		return this.timeout;
+	private Duration getResponseTimeout() {
+		return this.responseTimeout;
 	}
 
 
@@ -124,12 +142,12 @@ class DefaultWebTestClient implements WebTestClient {
 	}
 
 	@Override
-	public RequestBodyUriSpec method(HttpMethod method) {
-		return methodInternal(method);
+	public RequestBodyUriSpec method(HttpMethod httpMethod) {
+		return methodInternal(httpMethod);
 	}
 
-	private RequestBodyUriSpec methodInternal(HttpMethod method) {
-		return new DefaultRequestBodyUriSpec(this.webClient.method(method));
+	private RequestBodyUriSpec methodInternal(HttpMethod httpMethod) {
+		return new DefaultRequestBodyUriSpec(httpMethod);
 	}
 
 	@Override
@@ -145,154 +163,180 @@ class DefaultWebTestClient implements WebTestClient {
 
 	private class DefaultRequestBodyUriSpec implements RequestBodyUriSpec {
 
-		private final WebClient.RequestBodyUriSpec bodySpec;
+		private final HttpMethod httpMethod;
+
+		@Nullable
+		private URI uri;
+
+		private final HttpHeaders headers;
+
+		@Nullable
+		private MultiValueMap<String, String> cookies;
+
+		@Nullable
+		private BodyInserter<?, ? super ClientHttpRequest> inserter;
+
+		private final Map<String, Object> attributes = new LinkedHashMap<>(4);
+
+		@Nullable
+		private Consumer<ClientHttpRequest> httpRequestConsumer;
 
 		@Nullable
 		private String uriTemplate;
 
 		private final String requestId;
 
-		DefaultRequestBodyUriSpec(WebClient.RequestBodyUriSpec spec) {
-			this.bodySpec = spec;
+		DefaultRequestBodyUriSpec(HttpMethod httpMethod) {
+			this.httpMethod = httpMethod;
 			this.requestId = String.valueOf(requestIndex.incrementAndGet());
-			this.bodySpec.header(WebTestClient.WEBTESTCLIENT_REQUEST_ID, this.requestId);
+			this.headers = new HttpHeaders();
+			this.headers.add(WebTestClient.WEBTESTCLIENT_REQUEST_ID, this.requestId);
 		}
 
 		@Override
 		public RequestBodySpec uri(String uriTemplate, Object... uriVariables) {
-			this.bodySpec.uri(uriTemplate, uriVariables);
 			this.uriTemplate = uriTemplate;
-			return this;
+			return uri(uriBuilderFactory.expand(uriTemplate, uriVariables));
 		}
 
 		@Override
 		public RequestBodySpec uri(String uriTemplate, Map<String, ?> uriVariables) {
-			this.bodySpec.uri(uriTemplate, uriVariables);
 			this.uriTemplate = uriTemplate;
-			return this;
+			return uri(uriBuilderFactory.expand(uriTemplate, uriVariables));
 		}
 
 		@Override
 		public RequestBodySpec uri(Function<UriBuilder, URI> uriFunction) {
-			this.bodySpec.uri(uriFunction);
 			this.uriTemplate = null;
-			return this;
+			return uri(uriFunction.apply(uriBuilderFactory.builder()));
 		}
 
 		@Override
 		public RequestBodySpec uri(URI uri) {
-			this.bodySpec.uri(uri);
 			this.uriTemplate = null;
+			this.uri = uri;
 			return this;
 		}
 
+		private HttpHeaders getHeaders() {
+			return this.headers;
+		}
+
+		private MultiValueMap<String, String> getCookies() {
+			if (this.cookies == null) {
+				this.cookies = new LinkedMultiValueMap<>(3);
+			}
+			return this.cookies;
+		}
+
 		@Override
 		public RequestBodySpec header(String headerName, String... headerValues) {
-			this.bodySpec.header(headerName, headerValues);
+			for (String headerValue : headerValues) {
+				getHeaders().add(headerName, headerValue);
+			}
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec headers(Consumer<HttpHeaders> headersConsumer) {
-			this.bodySpec.headers(headersConsumer);
+			headersConsumer.accept(getHeaders());
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec attribute(String name, Object value) {
-			this.bodySpec.attribute(name, value);
+			this.attributes.put(name, value);
 			return this;
 		}
 
 		@Override
-		public RequestBodySpec attributes(
-				Consumer<Map<String, Object>> attributesConsumer) {
-			this.bodySpec.attributes(attributesConsumer);
+		public RequestBodySpec attributes(Consumer<Map<String, Object>> attributesConsumer) {
+			attributesConsumer.accept(this.attributes);
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec accept(MediaType... acceptableMediaTypes) {
-			this.bodySpec.accept(acceptableMediaTypes);
+			getHeaders().setAccept(Arrays.asList(acceptableMediaTypes));
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec acceptCharset(Charset... acceptableCharsets) {
-			this.bodySpec.acceptCharset(acceptableCharsets);
+			getHeaders().setAcceptCharset(Arrays.asList(acceptableCharsets));
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec contentType(MediaType contentType) {
-			this.bodySpec.contentType(contentType);
+			getHeaders().setContentType(contentType);
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec contentLength(long contentLength) {
-			this.bodySpec.contentLength(contentLength);
+			getHeaders().setContentLength(contentLength);
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec cookie(String name, String value) {
-			this.bodySpec.cookie(name, value);
+			getCookies().add(name, value);
 			return this;
 		}
 
 		@Override
-		public RequestBodySpec cookies(
-				Consumer<MultiValueMap<String, String>> cookiesConsumer) {
-			this.bodySpec.cookies(cookiesConsumer);
+		public RequestBodySpec cookies(Consumer<MultiValueMap<String, String>> cookiesConsumer) {
+			cookiesConsumer.accept(getCookies());
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec ifModifiedSince(ZonedDateTime ifModifiedSince) {
-			this.bodySpec.ifModifiedSince(ifModifiedSince);
+			getHeaders().setIfModifiedSince(ifModifiedSince);
 			return this;
 		}
 
 		@Override
 		public RequestBodySpec ifNoneMatch(String... ifNoneMatches) {
-			this.bodySpec.ifNoneMatch(ifNoneMatches);
+			getHeaders().setIfNoneMatch(Arrays.asList(ifNoneMatches));
 			return this;
 		}
 
 		@Override
 		public RequestHeadersSpec<?> bodyValue(Object body) {
-			this.bodySpec.bodyValue(body);
+			this.inserter = BodyInserters.fromValue(body);
 			return this;
 		}
 
 		@Override
-		public <T, S extends Publisher<T>> RequestHeadersSpec<?> body(S publisher, Class<T> elementClass) {
-			this.bodySpec.body(publisher, elementClass);
+		public <T, P extends Publisher<T>> RequestHeadersSpec<?> body(
+				P publisher, ParameterizedTypeReference<T> elementTypeRef) {
+			this.inserter = BodyInserters.fromPublisher(publisher, elementTypeRef);
 			return this;
 		}
 
 		@Override
-		public <T, S extends Publisher<T>> RequestHeadersSpec<?> body(S publisher, ParameterizedTypeReference<T> elementTypeRef) {
-			this.bodySpec.body(publisher, elementTypeRef);
+		public <T, P extends Publisher<T>> RequestHeadersSpec<?> body(P publisher, Class<T> elementClass) {
+			this.inserter = BodyInserters.fromPublisher(publisher, elementClass);
 			return this;
 		}
 
 		@Override
 		public RequestHeadersSpec<?> body(Object producer, Class<?> elementClass) {
-			this.bodySpec.body(producer, elementClass);
+			this.inserter = BodyInserters.fromProducer(producer, elementClass);
 			return this;
 		}
 
 		@Override
 		public RequestHeadersSpec<?> body(Object producer, ParameterizedTypeReference<?> elementTypeRef) {
-			this.bodySpec.body(producer, elementTypeRef);
+			this.inserter = BodyInserters.fromProducer(producer, elementTypeRef);
 			return this;
 		}
 
 		@Override
 		public RequestHeadersSpec<?> body(BodyInserter<?, ? super ClientHttpRequest> inserter) {
-			this.bodySpec.body(inserter);
+			this.inserter = inserter;
 			return this;
 		}
 
@@ -304,10 +348,57 @@ class DefaultWebTestClient implements WebTestClient {
 
 		@Override
 		public ResponseSpec exchange() {
-			ClientResponse clientResponse = this.bodySpec.exchange().block(getTimeout());
-			Assert.state(clientResponse != null, "No ClientResponse");
-			ExchangeResult result = wiretapConnector.getExchangeResult(this.requestId, this.uriTemplate, getTimeout());
-			return new DefaultResponseSpec(result, clientResponse, getTimeout());
+			ClientRequest request = (this.inserter != null ?
+					initRequestBuilder().body(this.inserter).build() :
+					initRequestBuilder().build());
+
+			ClientResponse response = exchangeFunction.exchange(request).block(getResponseTimeout());
+			Assert.state(response != null, "No ClientResponse");
+
+			ExchangeResult result = wiretapConnector.getExchangeResult(
+					this.requestId, this.uriTemplate, getResponseTimeout());
+
+			return new DefaultResponseSpec(result, response, getResponseTimeout());
+		}
+
+		private ClientRequest.Builder initRequestBuilder() {
+			ClientRequest.Builder builder = ClientRequest.create(this.httpMethod, initUri())
+					.headers(headers -> headers.addAll(initHeaders()))
+					.cookies(cookies -> cookies.addAll(initCookies()))
+					.attributes(attributes -> attributes.putAll(this.attributes));
+			if (this.httpRequestConsumer != null) {
+				builder.httpRequest(this.httpRequestConsumer);
+			}
+			return builder;
+		}
+
+		private URI initUri() {
+			return (this.uri != null ? this.uri : uriBuilderFactory.expand(""));
+		}
+
+		private HttpHeaders initHeaders() {
+			if (CollectionUtils.isEmpty(defaultHeaders)) {
+				return this.headers;
+			}
+			HttpHeaders result = new HttpHeaders();
+			result.putAll(defaultHeaders);
+			result.putAll(this.headers);
+			return result;
+		}
+
+		private MultiValueMap<String, String> initCookies() {
+			if (CollectionUtils.isEmpty(this.cookies)) {
+				return (defaultCookies != null ? defaultCookies : new LinkedMultiValueMap<>());
+			}
+			else if (CollectionUtils.isEmpty(defaultCookies)) {
+				return this.cookies;
+			}
+			else {
+				MultiValueMap<String, String> result = new LinkedMultiValueMap<>();
+				result.putAll(defaultCookies);
+				result.putAll(this.cookies);
+				return result;
+			}
 		}
 	}
 

spring-test/src/main/java/org/springframework/test/web/reactive/server/DefaultWebTestClientBuilder.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.
@@ -17,20 +17,30 @@
 package org.springframework.test.web.reactive.server;
 
 import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.client.reactive.ClientHttpConnector;
+import org.springframework.http.client.reactive.HttpComponentsClientHttpConnector;
+import org.springframework.http.client.reactive.JettyClientHttpConnector;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.http.codec.ClientCodecConfigurer;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.reactive.function.client.ExchangeFilterFunction;
+import org.springframework.web.reactive.function.client.ExchangeFunction;
+import org.springframework.web.reactive.function.client.ExchangeFunctions;
 import org.springframework.web.reactive.function.client.ExchangeStrategies;
-import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
+import org.springframework.web.util.DefaultUriBuilderFactory;
 import org.springframework.web.util.UriBuilderFactory;
 
 /**
@@ -41,7 +51,21 @@ import org.springframework.web.util.UriBuilderFactory;
  */
 class DefaultWebTestClientBuilder implements WebTestClient.Builder {
 
-	private final WebClient.Builder webClientBuilder;
+	private static final boolean reactorClientPresent;
+
+	private static final boolean jettyClientPresent;
+
+	private static final boolean httpComponentsClientPresent;
+
+	static {
+		ClassLoader loader = DefaultWebTestClientBuilder.class.getClassLoader();
+		reactorClientPresent = ClassUtils.isPresent("reactor.netty.http.client.HttpClient", loader);
+		jettyClientPresent = ClassUtils.isPresent("org.eclipse.jetty.client.HttpClient", loader);
+		httpComponentsClientPresent =
+				ClassUtils.isPresent("org.apache.hc.client5.http.impl.async.CloseableHttpAsyncClient", loader) &&
+						ClassUtils.isPresent("org.apache.hc.core5.reactive.ReactiveDataConsumer", loader);
+	}
+
 
 	@Nullable
 	private final WebHttpHandlerBuilder httpHandlerBuilder;
@@ -49,136 +73,243 @@ class DefaultWebTestClientBuilder implements WebTestClient.Builder {
 	@Nullable
 	private final ClientHttpConnector connector;
 
+	@Nullable
+	private String baseUrl;
+
+	@Nullable
+	private UriBuilderFactory uriBuilderFactory;
+
+	@Nullable
+	private HttpHeaders defaultHeaders;
+
+	@Nullable
+	private MultiValueMap<String, String> defaultCookies;
+
+	@Nullable
+	private List<ExchangeFilterFunction> filters;
+
+	@Nullable
+	private ExchangeStrategies strategies;
+
+	@Nullable
+	private List<Consumer<ExchangeStrategies.Builder>> strategiesConfigurers;
+
 	@Nullable
 	private Duration responseTimeout;
 
 
-	/** Connect to server via Reactor Netty. */
+	/** Determine connector via classpath detection. */
 	DefaultWebTestClientBuilder() {
-		this(new ReactorClientHttpConnector());
-	}
-
-	/** Connect to server through the given connector. */
-	DefaultWebTestClientBuilder(ClientHttpConnector connector) {
-		this(null, null, connector, null);
+		this(null, null);
 	}
 
-	/** Connect to given mock server with mock request and response. */
+	/** Use HttpHandlerConnector with mock server. */
 	DefaultWebTestClientBuilder(WebHttpHandlerBuilder httpHandlerBuilder) {
-		this(null, httpHandlerBuilder, null, null);
+		this(httpHandlerBuilder, null);
 	}
 
-	/** Copy constructor. */
-	DefaultWebTestClientBuilder(DefaultWebTestClientBuilder other) {
-		this(other.webClientBuilder.clone(), other.httpHandlerBuilder, other.connector,
-				other.responseTimeout);
+	/** Use given connector. */
+	DefaultWebTestClientBuilder(ClientHttpConnector connector) {
+		this(null, connector);
 	}
 
-	private DefaultWebTestClientBuilder(@Nullable WebClient.Builder webClientBuilder,
-			@Nullable WebHttpHandlerBuilder httpHandlerBuilder, @Nullable ClientHttpConnector connector,
-			@Nullable Duration responseTimeout) {
+	DefaultWebTestClientBuilder(
+			@Nullable WebHttpHandlerBuilder httpHandlerBuilder, @Nullable ClientHttpConnector connector) {
 
-		Assert.isTrue(httpHandlerBuilder != null || connector != null,
-				"Either WebHttpHandlerBuilder or ClientHttpConnector must be provided");
+		Assert.isTrue(httpHandlerBuilder == null || connector == null,
+				"Expected WebHttpHandlerBuilder or ClientHttpConnector but not both.");
 
-		this.webClientBuilder = (webClientBuilder != null ? webClientBuilder : WebClient.builder());
-		this.httpHandlerBuilder = (httpHandlerBuilder != null ? httpHandlerBuilder.clone() : null);
 		this.connector = connector;
-		this.responseTimeout = responseTimeout;
+		this.httpHandlerBuilder = (httpHandlerBuilder != null ? httpHandlerBuilder.clone() : null);
+	}
+
+	/** Copy constructor. */
+	DefaultWebTestClientBuilder(DefaultWebTestClientBuilder other) {
+		this.httpHandlerBuilder = (other.httpHandlerBuilder != null ? other.httpHandlerBuilder.clone() : null);
+		this.connector = other.connector;
+		this.responseTimeout = other.responseTimeout;
+
+		this.baseUrl = other.baseUrl;
+		this.uriBuilderFactory = other.uriBuilderFactory;
+		if (other.defaultHeaders != null) {
+			this.defaultHeaders = new HttpHeaders();
+			this.defaultHeaders.putAll(other.defaultHeaders);
+		}
+		else {
+			this.defaultHeaders = null;
+		}
+		this.defaultCookies = (other.defaultCookies != null ?
+				new LinkedMultiValueMap<>(other.defaultCookies) : null);
+		this.filters = (other.filters != null ? new ArrayList<>(other.filters) : null);
+		this.strategies = other.strategies;
+		this.strategiesConfigurers = (other.strategiesConfigurers != null ?
+				new ArrayList<>(other.strategiesConfigurers) : null);
 	}
 
 
 	@Override
 	public WebTestClient.Builder baseUrl(String baseUrl) {
-		this.webClientBuilder.baseUrl(baseUrl);
+		this.baseUrl = baseUrl;
 		return this;
 	}
 
 	@Override
 	public WebTestClient.Builder uriBuilderFactory(UriBuilderFactory uriBuilderFactory) {
-		this.webClientBuilder.uriBuilderFactory(uriBuilderFactory);
+		this.uriBuilderFactory = uriBuilderFactory;
 		return this;
 	}
 
 	@Override
-	public WebTestClient.Builder defaultHeader(String headerName, String... headerValues) {
-		this.webClientBuilder.defaultHeader(headerName, headerValues);
+	public WebTestClient.Builder defaultHeader(String header, String... values) {
+		initHeaders().put(header, Arrays.asList(values));
 		return this;
 	}
 
 	@Override
 	public WebTestClient.Builder defaultHeaders(Consumer<HttpHeaders> headersConsumer) {
-		this.webClientBuilder.defaultHeaders(headersConsumer);
+		headersConsumer.accept(initHeaders());
 		return this;
 	}
 
+	private HttpHeaders initHeaders() {
+		if (this.defaultHeaders == null) {
+			this.defaultHeaders = new HttpHeaders();
+		}
+		return this.defaultHeaders;
+	}
+
 	@Override
-	public WebTestClient.Builder defaultCookie(String cookieName, String... cookieValues) {
-		this.webClientBuilder.defaultCookie(cookieName, cookieValues);
+	public WebTestClient.Builder defaultCookie(String cookie, String... values) {
+		initCookies().addAll(cookie, Arrays.asList(values));
 		return this;
 	}
 
 	@Override
-	public WebTestClient.Builder defaultCookies(
-			Consumer<MultiValueMap<String, String>> cookiesConsumer) {
-		this.webClientBuilder.defaultCookies(cookiesConsumer);
+	public WebTestClient.Builder defaultCookies(Consumer<MultiValueMap<String, String>> cookiesConsumer) {
+		cookiesConsumer.accept(initCookies());
 		return this;
 	}
 
+	private MultiValueMap<String, String> initCookies() {
+		if (this.defaultCookies == null) {
+			this.defaultCookies = new LinkedMultiValueMap<>(3);
+		}
+		return this.defaultCookies;
+	}
+
 	@Override
 	public WebTestClient.Builder filter(ExchangeFilterFunction filter) {
-		this.webClientBuilder.filter(filter);
+		Assert.notNull(filter, "ExchangeFilterFunction must not be null");
+		initFilters().add(filter);
 		return this;
 	}
 
 	@Override
 	public WebTestClient.Builder filters(Consumer<List<ExchangeFilterFunction>> filtersConsumer) {
-		this.webClientBuilder.filters(filtersConsumer);
+		filtersConsumer.accept(initFilters());
 		return this;
 	}
 
+	private List<ExchangeFilterFunction> initFilters() {
+		if (this.filters == null) {
+			this.filters = new ArrayList<>();
+		}
+		return this.filters;
+	}
+
 	@Override
 	public WebTestClient.Builder codecs(Consumer<ClientCodecConfigurer> configurer) {
-		this.webClientBuilder.codecs(configurer);
+		if (this.strategiesConfigurers == null) {
+			this.strategiesConfigurers = new ArrayList<>(4);
+		}
+		this.strategiesConfigurers.add(builder -> builder.codecs(configurer));
 		return this;
 	}
 
 	@Override
 	public WebTestClient.Builder exchangeStrategies(ExchangeStrategies strategies) {
-		this.webClientBuilder.exchangeStrategies(strategies);
+		this.strategies = strategies;
 		return this;
 	}
 
-	@SuppressWarnings("deprecation")
 	@Override
+	@SuppressWarnings("deprecation")
 	public WebTestClient.Builder exchangeStrategies(Consumer<ExchangeStrategies.Builder> configurer) {
-		this.webClientBuilder.exchangeStrategies(configurer);
+		if (this.strategiesConfigurers == null) {
+			this.strategiesConfigurers = new ArrayList<>(4);
+		}
+		this.strategiesConfigurers.add(configurer);
 		return this;
 	}
 
 	@Override
-	public WebTestClient.Builder responseTimeout(Duration timeout) {
-		this.responseTimeout = timeout;
+	public WebTestClient.Builder apply(WebTestClientConfigurer configurer) {
+		configurer.afterConfigurerAdded(this, this.httpHandlerBuilder, this.connector);
 		return this;
 	}
 
 	@Override
-	public WebTestClient.Builder apply(WebTestClientConfigurer configurer) {
-		configurer.afterConfigurerAdded(this, this.httpHandlerBuilder, this.connector);
+	public WebTestClient.Builder responseTimeout(Duration timeout) {
+		this.responseTimeout = timeout;
 		return this;
 	}
 
-
 	@Override
 	public WebTestClient build() {
 		ClientHttpConnector connectorToUse = this.connector;
 		if (connectorToUse == null) {
-			Assert.state(this.httpHandlerBuilder != null, "No WebHttpHandlerBuilder available");
-			connectorToUse = new HttpHandlerConnector(this.httpHandlerBuilder.build());
+			if (this.httpHandlerBuilder != null) {
+				connectorToUse = new HttpHandlerConnector(this.httpHandlerBuilder.build());
+			}
+		}
+		if (connectorToUse == null) {
+			connectorToUse = initConnector();
+		}
+		Function<ClientHttpConnector, ExchangeFunction> exchangeFactory = connector -> {
+			ExchangeFunction exchange = ExchangeFunctions.create(connector, initExchangeStrategies());
+			if (CollectionUtils.isEmpty(this.filters)) {
+				return exchange;
+			}
+			return this.filters.stream()
+					.reduce(ExchangeFilterFunction::andThen)
+					.map(filter -> filter.apply(exchange))
+					.orElse(exchange);
+
+		};
+		return new DefaultWebTestClient(connectorToUse, exchangeFactory, initUriBuilderFactory(),
+				this.defaultHeaders != null ? HttpHeaders.readOnlyHttpHeaders(this.defaultHeaders) : null,
+				this.defaultCookies != null ? CollectionUtils.unmodifiableMultiValueMap(this.defaultCookies) : null,
+				this.responseTimeout, new DefaultWebTestClientBuilder(this));
+	}
+
+	private static ClientHttpConnector initConnector() {
+		if (reactorClientPresent) {
+			return new ReactorClientHttpConnector();
+		}
+		else if (jettyClientPresent) {
+			return new JettyClientHttpConnector();
+		}
+		else if (httpComponentsClientPresent) {
+			return new HttpComponentsClientHttpConnector();
 		}
+		throw new IllegalStateException("No suitable default ClientHttpConnector found");
+	}
 
-		return new DefaultWebTestClient(this.webClientBuilder,
-				connectorToUse, this.responseTimeout, new DefaultWebTestClientBuilder(this));
+	private ExchangeStrategies initExchangeStrategies() {
+		if (CollectionUtils.isEmpty(this.strategiesConfigurers)) {
+			return (this.strategies != null ? this.strategies : ExchangeStrategies.withDefaults());
+		}
+		ExchangeStrategies.Builder builder =
+				(this.strategies != null ? this.strategies.mutate() : ExchangeStrategies.builder());
+		this.strategiesConfigurers.forEach(configurer -> configurer.accept(builder));
+		return builder.build();
 	}
 
+	private UriBuilderFactory initUriBuilderFactory() {
+		if (this.uriBuilderFactory != null) {
+			return this.uriBuilderFactory;
+		}
+		return (this.baseUrl != null ?
+				new DefaultUriBuilderFactory(this.baseUrl) : new DefaultUriBuilderFactory());
+	}
 }

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

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java

@@ -49,7 +49,6 @@ import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.reactive.function.BodyInserter;
 import org.springframework.web.reactive.function.BodyInserters;
-import org.springframework.web.util.DefaultUriBuilderFactory;
 import org.springframework.web.util.UriBuilder;
 import org.springframework.web.util.UriBuilderFactory;
 
@@ -85,12 +84,12 @@ class DefaultWebClient implements WebClient {
 	private final DefaultWebClientBuilder builder;
 
 
-	DefaultWebClient(ExchangeFunction exchangeFunction, @Nullable UriBuilderFactory factory,
+	DefaultWebClient(ExchangeFunction exchangeFunction, UriBuilderFactory uriBuilderFactory,
 			@Nullable HttpHeaders defaultHeaders, @Nullable MultiValueMap<String, String> defaultCookies,
 			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest, DefaultWebClientBuilder builder) {
 
 		this.exchangeFunction = exchangeFunction;
-		this.uriBuilderFactory = (factory != null ? factory : new DefaultUriBuilderFactory());
+		this.uriBuilderFactory = uriBuilderFactory;
 		this.defaultHeaders = defaultHeaders;
 		this.defaultCookies = defaultCookies;
 		this.defaultRequest = defaultRequest;
@@ -147,6 +146,14 @@ 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 {
 
@@ -243,13 +250,6 @@ class DefaultWebClient implements WebClient {
 			return this;
 		}
 
-		@Override
-		public RequestBodySpec httpRequest(Consumer<ClientHttpRequest> requestConsumer) {
-			this.httpRequestConsumer = (this.httpRequestConsumer != null ?
-					this.httpRequestConsumer.andThen(requestConsumer) : requestConsumer);
-			return this;
-		}
-
 		@Override
 		public DefaultRequestBodyUriSpec accept(MediaType... acceptableMediaTypes) {
 			getHeaders().setAccept(Arrays.asList(acceptableMediaTypes));
@@ -298,6 +298,13 @@ class DefaultWebClient implements WebClient {
 			return this;
 		}
 
+		@Override
+		public RequestBodySpec httpRequest(Consumer<ClientHttpRequest> requestConsumer) {
+			this.httpRequestConsumer = (this.httpRequestConsumer != null ?
+					this.httpRequestConsumer.andThen(requestConsumer) : requestConsumer);
+			return this;
+		}
+
 		@Override
 		public RequestHeadersSpec<?> bodyValue(Object body) {
 			this.inserter = BodyInserters.fromValue(body);
@@ -342,6 +349,65 @@ 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 +464,6 @@ 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 +567,11 @@ 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 +581,6 @@ 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();

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClientBuilder.java

@@ -262,24 +262,26 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 
 	@Override
 	public WebClient build() {
+		ClientHttpConnector connectorToUse =
+				(this.connector != null ? this.connector : initConnector());
+
 		ExchangeFunction exchange = (this.exchangeFunction == null ?
-				ExchangeFunctions.create(getOrInitConnector(), initExchangeStrategies()) :
+				ExchangeFunctions.create(connectorToUse, initExchangeStrategies()) :
 				this.exchangeFunction);
+
 		ExchangeFunction filteredExchange = (this.filters != null ? this.filters.stream()
 				.reduce(ExchangeFilterFunction::andThen)
 				.map(filter -> filter.apply(exchange))
 				.orElse(exchange) : exchange);
+
 		return new DefaultWebClient(filteredExchange, initUriBuilderFactory(),
 				this.defaultHeaders != null ? HttpHeaders.readOnlyHttpHeaders(this.defaultHeaders) : null,
 				this.defaultCookies != null ? CollectionUtils.unmodifiableMultiValueMap(this.defaultCookies) : null,
 				this.defaultRequest, new DefaultWebClientBuilder(this));
 	}
 
-	private ClientHttpConnector getOrInitConnector() {
-		if (this.connector != null) {
-			return this.connector;
-		}
-		else if (reactorClientPresent) {
+	private ClientHttpConnector initConnector() {
+		if (reactorClientPresent) {
 			return new ReactorClientHttpConnector();
 		}
 		else if (jettyClientPresent) {

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();
 	}
 

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()
 

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();
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultWebClientTests.java

@@ -43,6 +43,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.when;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
@@ -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");
 	}

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 -> {

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 -> {

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();
 	}

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();
 	}
 

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())

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();
 	}

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/client/WebClientExtensionsTests.kt

@@ -80,6 +80,7 @@ class WebClientExtensionsTests {
 	}
 
 	@Test
+	@Suppress("DEPRECATION")
 	fun awaitExchange() {
 		val response = mockk<ClientResponse>()
 		every { requestBodySpec.exchange() } returns Mono.just(response)

src/docs/asciidoc/web/webflux-webclient.adoc

@@ -1,16 +1,20 @@
 [[webflux-client]]
 = WebClient
 
-Spring WebFlux includes a reactive, non-blocking `WebClient` for HTTP requests. The client
-has a functional, fluent API with reactive types for declarative composition, see
-<<web-reactive.adoc#webflux-reactive-libraries>>. WebFlux client and server rely on the
-same non-blocking <<web-reactive.adoc#webflux-codecs, codecs>> to encode and decode request
-and response content.
+Spring WebFlux includes a client to perform HTTP requests with. `WebClient` has a
+functional, fluent API based on Reactor, see <<web-reactive.adoc#webflux-reactive-libraries>>,
+which enables declarative composition of asynchronous logic without the need to deal with
+threads or concurrency. It is fully non-blocking, it supports streaming, and relies on
+the same <<web-reactive.adoc#webflux-codecs, codecs>> that are also used to encode and
+decode request and response content on the server side.
 
-Internally `WebClient` delegates to an HTTP client library. By default, it uses
-https://github.com/reactor/reactor-netty[Reactor Netty], there is built-in support for
-the Jetty https://github.com/jetty-project/jetty-reactive-httpclient[reactive HttpClient],
-and others can be plugged in through a `ClientHttpConnector`.
+`WebClient` needs an HTTP client library to perform requests with. There is built-in
+support for the following:
+
+* https://github.com/reactor/reactor-netty[Reactor Netty]
+* https://github.com/jetty-project/jetty-reactive-httpclient[Jetty Reactive HttpClient]
+* https://hc.apache.org/index.html[Apache HttpComponents]
+* Others can be plugged via `ClientHttpConnector`.
 
 
 
@@ -23,12 +27,10 @@ The simplest way to create a `WebClient` is through one of the static factory me
 * `WebClient.create()`
 * `WebClient.create(String baseUrl)`
 
-The above methods use the Reactor Netty `HttpClient` with default settings and expect
-`io.projectreactor.netty:reactor-netty` to be on the classpath.
-
 You can also use `WebClient.builder()` with further options:
 
 * `uriBuilderFactory`: Customized `UriBuilderFactory` to use as a base URL.
+* `defaultUriVariables`: default values to use when expanding URI templates.
 * `defaultHeader`: Headers for every request.
 * `defaultCookie`: Cookies for every request.
 * `defaultRequest`: `Consumer` to customize every request.
@@ -36,33 +38,25 @@ You can also use `WebClient.builder()` with further options:
 * `exchangeStrategies`: HTTP message reader/writer customizations.
 * `clientConnector`: HTTP client library settings.
 
-The following example configures <<web-reactive.adoc#webflux-codecs, HTTP codecs>>:
+For example:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
 	WebClient client = WebClient.builder()
-			.exchangeStrategies(builder -> {
-					return builder.codecs(codecConfigurer -> {
-						//...
-					});
-			})
+			.codecs(configurer -> ... )
 			.build();
 ----
 [source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
 .Kotlin
 ----
 	val webClient = WebClient.builder()
-			.exchangeStrategies { strategies ->
-				strategies.codecs {
-					//...
-				}
-			}
+			.codecs { configurer -> ... }
 			.build()
 ----
 
-Once built, a `WebClient` instance is immutable. However, you can clone it and build a
-modified copy without affecting the original instance, as the following example shows:
+Once built, a `WebClient` is immutable. However, you can clone it and build a
+modified copy as follows:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
@@ -94,37 +88,29 @@ modified copy without affecting the original instance, as the following example
 [[webflux-client-builder-maxinmemorysize]]
 === MaxInMemorySize
 
-Spring WebFlux configures <<web-reactive.adoc#webflux-codecs-limits,limits>> for buffering
-data in-memory in codec to avoid application memory issues. By the default this is
-configured to 256KB and if that's not enough for your use case, you'll see the following:
+Codecs have <<web-reactive.adoc#webflux-codecs-limits,limits>> for buffering data in
+memory to avoid application memory issues. By the default those are set to 256KB.
+If that's not enough you'll get the following error:
 
 ----
 org.springframework.core.io.buffer.DataBufferLimitException: Exceeded limit on max bytes to buffer
 ----
 
-You can configure this limit on all default codecs with the following code sample:
+To change the limit for default codecs, use the following:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
 	WebClient webClient = WebClient.builder()
-			.exchangeStrategies(builder ->
-				builder.codecs(codecs ->
-					codecs.defaultCodecs().maxInMemorySize(2 * 1024 * 1024)
-				)
-			)
+			.codecs(configurer -> configurer.defaultCodecs().maxInMemorySize(2 * 1024 * 1024));
 			.build();
 ----
 [source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
 .Kotlin
 ----
 	val webClient = WebClient.builder()
-		.exchangeStrategies { builder ->
-				builder.codecs {
-					it.defaultCodecs().maxInMemorySize(2 * 1024 * 1024)
-				}
-		}
-		.build()
+			.codecs { configurer -> configurer.defaultCodecs().maxInMemorySize(2 * 1024 * 1024) }
+			.build()
 ----
 
 
@@ -132,7 +118,7 @@ You can configure this limit on all default codecs with the following code sampl
 [[webflux-client-builder-reactor]]
 === Reactor Netty
 
-To customize Reactor Netty settings, simple provide a pre-configured `HttpClient`:
+To customize Reactor Netty settings, provide a pre-configured `HttpClient`:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
@@ -457,8 +443,30 @@ The following example shows how to customize Apache HttpComponents `HttpClient`
 [[webflux-client-retrieve]]
 == `retrieve()`
 
-The `retrieve()` method is the easiest way to get a response body and decode it.
-The following example shows how to do so:
+The `retrieve()` method can be used to declare how to extract the response. For example:
+
+[source,java,indent=0,subs="verbatim,quotes",role="primary"]
+.Java
+----
+	WebClient client = WebClient.create("https://example.org");
+
+	Mono<ResponseEntity<Person>> result = client.get()
+			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
+			.retrieve()
+			.toEntity(Person.class);
+----
+[source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
+.Kotlin
+----
+	val client = WebClient.create("https://example.org")
+
+	val result = client.get()
+			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
+			.retrieve()
+			.toEntity<Person>().awaitSingle()
+----
+
+Or to get only the body:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
@@ -481,7 +489,7 @@ The following example shows how to do so:
 			.awaitBody<Person>()
 ----
 
-You can also get a stream of objects decoded from the response, as the following example shows:
+To get a stream of decoded objects:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
@@ -500,11 +508,9 @@ You can also get a stream of objects decoded from the response, as the following
 			.bodyToFlow<Quote>()
 ----
 
-By default, responses with 4xx or 5xx status codes result in an
-`WebClientResponseException` or one of its HTTP status specific sub-classes, such as
-`WebClientResponseException.BadRequest`, `WebClientResponseException.NotFound`, and others.
-You can also use the `onStatus` method to customize the resulting exception,
-as the following example shows:
+By default, 4xx or 5xx responses result in an `WebClientResponseException`, including
+sub-classes for specific HTTP status codes. To customize the handling of error
+responses, use `onStatus` handlers as follows:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
@@ -527,67 +533,44 @@ as the following example shows:
 			.awaitBody<Person>()
 ----
 
-When `onStatus` is used, if the response is expected to have content, then the `onStatus`
-callback should consume it. If not, the content will be automatically drained to ensure
-resources are released.
-
 
 
 
 [[webflux-client-exchange]]
-== `exchange()`
+== `exchangeToMono()`
 
-The `exchange()` method provides more control than the `retrieve` method. The following example is equivalent
-to `retrieve()` but also provides access to the `ClientResponse`:
+The `exchangeToMono()` and `exchangeToFlux()` methods are useful for more advanced
+cases that require more control, such as to decode the response differently
+depending on the response status:
 
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
-	Mono<Person> result = client.get()
-			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
-			.exchange()
-			.flatMap(response -> response.bodyToMono(Person.class));
+	Mono<Object> 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());
+			   }
+		   });
 ----
 [source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
 .Kotlin
 ----
-	val result = client.get()
-			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
-			.awaitExchange()
-			.awaitBody<Person>()
 ----
 
-At this level, you can also create a full `ResponseEntity`:
+When using the above, after the returned `Mono` or `Flux` completes, the response body
+is checked and if not consumed it is released to prevent memory and connection leaks.
+Therefore the response cannot be decoded further downstream. It is up to the provided
+function to declare how to decode the response if needed.
 
-[source,java,indent=0,subs="verbatim,quotes",role="primary"]
-.Java
-----
-	Mono<ResponseEntity<Person>> result = client.get()
-			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
-			.exchange()
-			.flatMap(response -> response.toEntity(Person.class));
-----
-[source,kotlin,indent=0,subs="verbatim,quotes",role="secondary"]
-.Kotlin
-----
-	val result = client.get()
-			.uri("/persons/{id}", id).accept(MediaType.APPLICATION_JSON)
-			.awaitExchange()
-			.toEntity<Person>()
-----
-
-Note that (unlike `retrieve()`), with `exchange()`, there are no automatic error signals for
-4xx and 5xx responses. You have to check the status code and decide how to proceed.
-
-[CAUTION]
-====
-Unlike `retrieve()`, when using `exchange()`, it is the responsibility of the application
-to consume any response content regardless of the scenario (success, error, unexpected
-data, etc). Not doing so can cause a memory leak. The Javadoc for `ClientResponse` lists
-all the available options for consuming the body. Generally prefer using `retrieve()`
-unless you have a good reason for using `exchange()` which does allow to check the
-response status and headers before deciding how to or if to consume the response.
-====