Add defaultRequest option to WebClient.Builder

Issue: SPR-16873

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

@@ -79,17 +79,21 @@ class DefaultWebClient implements WebClient {
 	@Nullable
 	private final MultiValueMap<String, String> defaultCookies;
 
+	@Nullable
+	private final Consumer<RequestHeadersSpec<?>> defaultRequest;
+
 	private final DefaultWebClientBuilder builder;
 
 
 	DefaultWebClient(ExchangeFunction exchangeFunction, @Nullable UriBuilderFactory factory,
 			@Nullable HttpHeaders defaultHeaders, @Nullable MultiValueMap<String, String> defaultCookies,
-			DefaultWebClientBuilder builder) {
+			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest, DefaultWebClientBuilder builder) {
 
 		this.exchangeFunction = exchangeFunction;
 		this.uriBuilderFactory = (factory != null ? factory : new DefaultUriBuilderFactory());
 		this.defaultHeaders = defaultHeaders;
 		this.defaultCookies = defaultCookies;
+		this.defaultRequest = defaultRequest;
 		this.builder = builder;
 	}
 
@@ -317,6 +321,9 @@ class DefaultWebClient implements WebClient {
 		}
 
 		private ClientRequest.Builder initRequestBuilder() {
+			if (defaultRequest != null) {
+				defaultRequest.accept(this);
+			}
 			URI uri = (this.uri != null ? this.uri : uriBuilderFactory.expand(""));
 			return ClientRequest.create(this.httpMethod, uri)
 					.headers(headers -> headers.addAll(initHeaders()))

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

@@ -57,6 +57,9 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 	@Nullable
 	private MultiValueMap<String, String> defaultCookies;
 
+	@Nullable
+	private Consumer<WebClient.RequestHeadersSpec<?>> defaultRequest;
+
 	@Nullable
 	private List<ExchangeFilterFunction> filters;
 
@@ -89,6 +92,7 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 		}
 		this.defaultCookies =
 				other.defaultCookies != null ? new LinkedMultiValueMap<>(other.defaultCookies) : null;
+		this.defaultRequest = other.defaultRequest;
 		this.filters = other.filters != null ? new ArrayList<>(other.filters) : null;
 		this.connector = other.connector;
 		this.exchangeFunction = other.exchangeFunction;
@@ -152,6 +156,13 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 		return this.defaultCookies;
 	}
 
+	@Override
+	public WebClient.Builder defaultRequest(Consumer<WebClient.RequestHeadersSpec<?>> defaultRequest) {
+		this.defaultRequest = this.defaultRequest != null ?
+				this.defaultRequest.andThen(defaultRequest) : defaultRequest;
+		return this;
+	}
+
 	@Override
 	public WebClient.Builder clientConnector(ClientHttpConnector connector) {
 		this.connector = connector;
@@ -201,7 +212,7 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 		return new DefaultWebClient(filteredExchange, initUriBuilderFactory(),
 				this.defaultHeaders != null ? unmodifiableCopy(this.defaultHeaders) : null,
 				this.defaultCookies != null ? unmodifiableCopy(this.defaultCookies) : null,
-				new DefaultWebClientBuilder(this));
+				this.defaultRequest, new DefaultWebClientBuilder(this));
 	}
 
 	private ExchangeFunction initExchangeFunction() {

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

@@ -226,7 +226,7 @@ public interface WebClient {
 		Builder uriBuilderFactory(UriBuilderFactory uriBuilderFactory);
 
 		/**
-		 * A global option to specify a header to be added to every request,
+		 * Global option to specify a header to be added to every request,
 		 * if the request does not already contain such a header.
 		 * @param header the header name
 		 * @param values the header values
@@ -241,7 +241,7 @@ public interface WebClient {
 		Builder defaultHeaders(Consumer<HttpHeaders> headersConsumer);
 
 		/**
-		 * A global option to specify a cookie to be added to every request,
+		 * Global option to specify a cookie to be added to every request,
 		 * if the request does not already contain such a cookie.
 		 * @param cookie the cookie name
 		 * @param values the cookie values
@@ -255,6 +255,14 @@ 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()}.
+		 * @param defaultRequest the consumer to use for modifying requests
+		 * @since 5.1
+		 */
+		Builder defaultRequest(Consumer<RequestHeadersSpec<?>> defaultRequest);
+
 		/**
 		 * Add the given filter to the filter chain.
 		 * @param filter the filter to be added to the chain