Client support for API versioning

Closes gh-34567

spring-web/src/main/java/org/springframework/web/client/ApiVersionFormatter.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2002-2025 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client;
+
+/**
+ * Contract to format the API version for a request.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ * @see DefaultApiVersionInserter.Builder#withVersionFormatter(ApiVersionFormatter)
+ */
+@FunctionalInterface
+public interface ApiVersionFormatter {
+
+	/**
+	 * Format the given version Object into a String value.
+	 * @param version the version to format
+	 * @return the final String version to use
+	 */
+	String formatVersion(Object version);
+
+}

spring-web/src/main/java/org/springframework/web/client/ApiVersionInserter.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2002-2025 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client;
+
+import java.net.URI;
+
+import org.springframework.http.HttpHeaders;
+
+/**
+ * Contract to determine how to insert an API version into the URI or headers
+ * of a request.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ */
+public interface ApiVersionInserter {
+
+	/**
+	 * Allows inserting the version into the URI.
+	 * @param version the version to insert
+	 * @param uri the URI for the request
+	 * @return the updated or the same URI
+	 */
+	default URI insertVersion(Object version, URI uri) {
+		return uri;
+	}
+
+	/**
+	 * Allows inserting the version into request headers.
+	 * @param version the version to insert
+	 * @param headers the request headers
+	 */
+	default void insertVersion(Object version, HttpHeaders headers) {
+	}
+
+}

spring-web/src/main/java/org/springframework/web/client/DefaultApiVersionInserter.java

@@ -0,0 +1,193 @@
+/*
+ * Copyright 2002-2025 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client;
+
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.Assert;
+import org.springframework.web.util.UriComponentsBuilder;
+
+/**
+ * Default implementation of {@link ApiVersionInserter} to insert the version
+ * into a request header, query parameter, or the URL path.
+ *
+ * <p>Use {@link #builder()} to create an instance.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ */
+public final class DefaultApiVersionInserter implements ApiVersionInserter {
+
+	private final @Nullable String header;
+
+	private final @Nullable String queryParam;
+
+	private final @Nullable Integer pathSegmentIndex;
+
+	private final ApiVersionFormatter versionFormatter;
+
+
+	private DefaultApiVersionInserter(
+			@Nullable String header, @Nullable String queryParam, @Nullable Integer pathSegmentIndex,
+			@Nullable ApiVersionFormatter formatter) {
+
+		Assert.isTrue(header != null || queryParam != null || pathSegmentIndex != null,
+				"Expected 'header', 'queryParam', or 'pathSegmentIndex' to be configured");
+
+		this.header = header;
+		this.queryParam = queryParam;
+		this.pathSegmentIndex = pathSegmentIndex;
+		this.versionFormatter = (formatter != null ? formatter : Object::toString);
+	}
+
+
+	@Override
+	public URI insertVersion(Object version, URI uri) {
+		if (this.queryParam == null && this.pathSegmentIndex == null) {
+			return uri;
+		}
+		String formattedVersion = this.versionFormatter.formatVersion(version);
+		UriComponentsBuilder builder = UriComponentsBuilder.fromUri(uri);
+		if (this.queryParam != null) {
+			builder.queryParam(this.queryParam, formattedVersion);
+		}
+		if (this.pathSegmentIndex != null) {
+			List<String> pathSegments = new ArrayList<>(builder.build().getPathSegments());
+			assertPathSegmentIndex(this.pathSegmentIndex, pathSegments.size(), uri);
+			pathSegments.add(this.pathSegmentIndex, formattedVersion);
+			builder.replacePath(null);
+			pathSegments.forEach(builder::pathSegment);
+		}
+		return builder.build().toUri();
+	}
+
+	private void assertPathSegmentIndex(Integer index, int pathSegmentsSize, URI uri) {
+		Assert.state(index <= pathSegmentsSize,
+				"Cannot insert version into '" + uri.getPath() + "' at path segment index " + index);
+	}
+
+	@Override
+	public void insertVersion(Object version, HttpHeaders headers) {
+		if (this.header != null) {
+			headers.set(this.header, this.versionFormatter.formatVersion(version));
+		}
+	}
+
+
+	/**
+	 * Create a builder for an inserter that sets a header.
+	 * @param header the name of a header to hold the version
+	 */
+	public static Builder fromHeader(@Nullable String header) {
+		return new Builder(header, null, null);
+	}
+
+	/**
+	 * Create a builder for an inserter that sets a query parameter.
+	 * @param queryParam the name of a query parameter to hold the version
+	 */
+	public static Builder fromQueryParam(@Nullable String queryParam) {
+		return new Builder(null, queryParam, null);
+	}
+
+	/**
+	 * Create a builder for an inserter that inserts a path segment.
+	 * @param pathSegmentIndex the index of the path segment to hold the version
+	 */
+	public static Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
+		return new Builder(null, null, pathSegmentIndex);
+	}
+
+	/**
+	 * Create a builder.
+	 */
+	public static Builder builder() {
+		return new Builder(null, null, null);
+	}
+
+
+	/**
+	 * A builder for {@link DefaultApiVersionInserter}.
+	 */
+	public static final class Builder {
+
+		private @Nullable String header;
+
+		private @Nullable String queryParam;
+
+		private @Nullable Integer pathSegmentIndex;
+
+		private @Nullable ApiVersionFormatter versionFormatter;
+
+		private Builder(@Nullable String header, @Nullable String queryParam, @Nullable Integer pathSegmentIndex) {
+			this.header = header;
+			this.queryParam = queryParam;
+			this.pathSegmentIndex = pathSegmentIndex;
+		}
+
+		/**
+		 * Configure the inserter to set a header.
+		 * @param header the name of the header to hold the version
+		 */
+		public Builder fromHeader(@Nullable String header) {
+			this.header = header;
+			return this;
+		}
+
+		/**
+		 * Configure the inserter to set a query parameter.
+		 * @param queryParam the name of the query parameter to hold the version
+		 */
+		public Builder fromQueryParam(@Nullable String queryParam) {
+			this.queryParam = queryParam;
+			return this;
+		}
+
+		/**
+		 * Configure the inserter to insert a path segment.
+		 * @param pathSegmentIndex the index of the path segment to hold the version
+		 */
+		public Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
+			this.pathSegmentIndex = pathSegmentIndex;
+			return this;
+		}
+
+		/**
+		 * Format the version Object into a String using the given {@link ApiVersionFormatter}.
+		 * <p>By default, the version is formatted with {@link Object#toString()}.
+		 * @param versionFormatter the formatter to use
+		 */
+		public Builder withVersionFormatter(ApiVersionFormatter versionFormatter) {
+			this.versionFormatter = versionFormatter;
+			return this;
+		}
+
+		/**
+		 * Build the inserter.
+		 */
+		public ApiVersionInserter build() {
+			return new DefaultApiVersionInserter(
+					this.header, this.queryParam, this.pathSegmentIndex, this.versionFormatter);
+		}
+	}
+
+}

spring-web/src/main/java/org/springframework/web/client/DefaultRestClient.java

@@ -108,6 +108,8 @@ final class DefaultRestClient implements RestClient {
 
 	private final @Nullable MultiValueMap<String, String> defaultCookies;
 
+	private final @Nullable ApiVersionInserter apiVersionInserter;
+
 	private final @Nullable Consumer<RequestHeadersSpec<?>> defaultRequest;
 
 	private final List<StatusHandler> defaultStatusHandlers;
@@ -128,6 +130,7 @@ final class DefaultRestClient implements RestClient {
 			UriBuilderFactory uriBuilderFactory,
 			@Nullable HttpHeaders defaultHeaders,
 			@Nullable MultiValueMap<String, String> defaultCookies,
+			@Nullable ApiVersionInserter apiVersionInserter,
 			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest,
 			@Nullable List<StatusHandler> statusHandlers,
 			List<HttpMessageConverter<?>> messageConverters,
@@ -142,6 +145,7 @@ final class DefaultRestClient implements RestClient {
 		this.uriBuilderFactory = uriBuilderFactory;
 		this.defaultHeaders = defaultHeaders;
 		this.defaultCookies = defaultCookies;
+		this.apiVersionInserter = apiVersionInserter;
 		this.defaultRequest = defaultRequest;
 		this.defaultStatusHandlers = (statusHandlers != null ? new ArrayList<>(statusHandlers) : new ArrayList<>());
 		this.messageConverters = messageConverters;
@@ -293,6 +297,8 @@ final class DefaultRestClient implements RestClient {
 
 		private @Nullable MultiValueMap<String, String> cookies;
 
+		private @Nullable Object apiVersion;
+
 		private @Nullable InternalBody body;
 
 		private @Nullable Map<String, Object> attributes;
@@ -417,6 +423,12 @@ final class DefaultRestClient implements RestClient {
 			return this;
 		}
 
+		@Override
+		public RequestBodySpec apiVersion(Object version) {
+			this.apiVersion = version;
+			return this;
+		}
+
 		@Override
 		public RequestBodySpec attribute(String name, Object value) {
 			getAttributes().put(name, value);
@@ -589,7 +601,12 @@ final class DefaultRestClient implements RestClient {
 		}
 
 		private URI initUri() {
-			return (this.uri != null ? this.uri : DefaultRestClient.this.uriBuilderFactory.expand(""));
+			URI uriToUse = this.uri != null ? this.uri : DefaultRestClient.this.uriBuilderFactory.expand("");
+			if (this.apiVersion != null) {
+				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
+				uriToUse = apiVersionInserter.insertVersion(this.apiVersion, uriToUse);
+			}
+			return uriToUse;
 		}
 
 		private @Nullable String serializeCookies() {
@@ -628,18 +645,29 @@ final class DefaultRestClient implements RestClient {
 
 		private @Nullable HttpHeaders initHeaders() {
 			HttpHeaders defaultHeaders = DefaultRestClient.this.defaultHeaders;
-			if (this.headers == null || this.headers.isEmpty()) {
-				return defaultHeaders;
-			}
-			else if (defaultHeaders == null || defaultHeaders.isEmpty()) {
-				return this.headers;
+			if (this.apiVersion == null) {
+				if (this.headers == null || this.headers.isEmpty()) {
+					return defaultHeaders;
+				}
+				else if (defaultHeaders == null || defaultHeaders.isEmpty()) {
+					return this.headers;
+				}
 			}
-			else {
-				HttpHeaders result = new HttpHeaders();
+
+			HttpHeaders result = new HttpHeaders();
+			if (defaultHeaders != null) {
 				result.putAll(defaultHeaders);
+			}
+			if (this.headers != null) {
 				result.putAll(this.headers);
-				return result;
 			}
+
+			if (this.apiVersion != null) {
+				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
+				apiVersionInserter.insertVersion(this.apiVersion, result);
+			}
+
+			return result;
 		}
 
 		private ClientHttpRequest createRequest(URI uri) throws IOException {

spring-web/src/main/java/org/springframework/web/client/DefaultRestClientBuilder.java

@@ -150,6 +150,8 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 
 	private @Nullable MultiValueMap<String, String> defaultCookies;
 
+	private @Nullable ApiVersionInserter apiVersionInserter;
+
 	private @Nullable Consumer<RestClient.RequestHeadersSpec<?>> defaultRequest;
 
 	private @Nullable List<StatusHandler> statusHandlers;
@@ -186,6 +188,7 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 			this.defaultHeaders = null;
 		}
 		this.defaultCookies = (other.defaultCookies != null ? new LinkedMultiValueMap<>(other.defaultCookies) : null);
+		this.apiVersionInserter = other.apiVersionInserter;
 		this.defaultRequest = other.defaultRequest;
 		this.statusHandlers = (other.statusHandlers != null ? new ArrayList<>(other.statusHandlers) : null);
 		this.interceptors = (other.interceptors != null) ? new ArrayList<>(other.interceptors) : null;
@@ -321,6 +324,12 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 		return this.defaultCookies;
 	}
 
+	@Override
+	public RestClient.Builder apiVersionInserter(ApiVersionInserter apiVersionInserter) {
+		this.apiVersionInserter = apiVersionInserter;
+		return this;
+	}
+
 	@Override
 	public RestClient.Builder defaultRequest(Consumer<RestClient.RequestHeadersSpec<?>> defaultRequest) {
 		this.defaultRequest = this.defaultRequest != null ?
@@ -513,9 +522,8 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 		return new DefaultRestClient(
 				requestFactory, this.interceptors, this.bufferingPredicate, this.initializers,
 				uriBuilderFactory, defaultHeaders, defaultCookies,
-				this.defaultRequest,
-				this.statusHandlers,
-				converters,
+				this.apiVersionInserter, this.defaultRequest,
+				this.statusHandlers, converters,
 				this.observationRegistry, this.observationConvention,
 				new DefaultRestClientBuilder(this));
 	}

spring-web/src/main/java/org/springframework/web/client/RestClient.java

@@ -332,6 +332,15 @@ public interface RestClient {
 		 */
 		Builder defaultCookies(Consumer<MultiValueMap<String, String>> cookiesConsumer);
 
+		/**
+		 * Configure an {@link ApiVersionInserter} to abstract how an API version
+		 * specified via {@link RequestHeadersSpec#apiVersion(Object)}
+		 * is inserted into the request.
+		 * @param apiVersionInserter the inserter to use
+		 * @since 7.0
+		 */
+		Builder apiVersionInserter(ApiVersionInserter apiVersionInserter);
+
 		/**
 		 * Provide a consumer to customize every request being built.
 		 * @param defaultRequest the consumer to use for modifying requests
@@ -596,6 +605,17 @@ public interface RestClient {
 		 */
 		S headers(Consumer<HttpHeaders> headersConsumer);
 
+		/**
+		 * Set an API version for the request. The version is inserted into the
+		 * request by the {@link Builder#apiVersionInserter(ApiVersionInserter)
+		 * configured} {@code ApiVersionInserter}.
+		 * @param version the API version of the request; this can be a String or
+		 * some Object that can be formatted the inserter, e.g. through an
+		 * {@link ApiVersionFormatter}.
+		 * @since 7.0
+		 */
+		S apiVersion(Object version);
+
 		/**
 		 * Set the attribute with the given name to the given value.
 		 * @param name the name of the attribute to add

spring-web/src/main/java/org/springframework/web/client/support/RestClientAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -121,6 +121,10 @@ public final class RestClientAdapter implements HttpExchangeAdapter {
 			bodySpec.header(HttpHeaders.COOKIE, String.join("; ", cookies));
 		}
 
+		if (values.getApiVersion() != null) {
+			bodySpec.apiVersion(values.getApiVersion());
+		}
+
 		bodySpec.attributes(attributes -> attributes.putAll(values.getAttributes()));
 
 		if (values.getBodyValue() != null) {

spring-web/src/main/java/org/springframework/web/service/annotation/DeleteExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -67,4 +67,11 @@ public @interface DeleteExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#version()}.
+	 * @since 7.0
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/GetExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -54,4 +54,11 @@ public @interface GetExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] accept() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#version()}.
+	 * @since 7.0
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/HttpExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -185,4 +185,10 @@ public @interface HttpExchange {
 	 */
 	String[] headers() default {};
 
+	/**
+	 * The API version associated with the request.
+	 * @since 7.0
+	 */
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PatchExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -67,4 +67,11 @@ public @interface PatchExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#version()}.
+	 * @since 7.0
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PostExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -67,4 +67,11 @@ public @interface PostExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#version()}.
+	 * @since 7.0
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PutExchange.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -67,4 +67,11 @@ public @interface PutExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] headers() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#version()}.
+	 * @since 7.0
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String version() default "";
+
 }

spring-web/src/main/java/org/springframework/web/service/invoker/HttpRequestValues.java

@@ -67,6 +67,8 @@ public class HttpRequestValues {
 
 	private final MultiValueMap<String, String> cookies;
 
+	private @Nullable Object version;
+
 	private final Map<String, Object> attributes;
 
 	private final @Nullable Object bodyValue;
@@ -79,8 +81,8 @@ public class HttpRequestValues {
 	protected HttpRequestValues(@Nullable HttpMethod httpMethod,
 			@Nullable URI uri, @Nullable UriBuilderFactory uriBuilderFactory,
 			@Nullable String uriTemplate, Map<String, String> uriVariables,
-			HttpHeaders headers, MultiValueMap<String, String> cookies, Map<String, Object> attributes,
-			@Nullable Object bodyValue) {
+			HttpHeaders headers, MultiValueMap<String, String> cookies, @Nullable Object version,
+			Map<String, Object> attributes, @Nullable Object bodyValue) {
 
 		Assert.isTrue(uri != null || uriTemplate != null, "Neither URI nor URI template");
 
@@ -91,6 +93,7 @@ public class HttpRequestValues {
 		this.uriVariables = uriVariables;
 		this.headers = headers;
 		this.cookies = cookies;
+		this.version = version;
 		this.attributes = attributes;
 		this.bodyValue = bodyValue;
 	}
@@ -154,6 +157,10 @@ public class HttpRequestValues {
 		return this.cookies;
 	}
 
+	public @Nullable Object getApiVersion() {
+		return this.version;
+	}
+
 	/**
 	 * Return the attributes associated with the request, or an empty map.
 	 */
@@ -225,6 +232,8 @@ public class HttpRequestValues {
 
 		private @Nullable MultiValueMap<String, Object> parts;
 
+		private @Nullable Object version;
+
 		private @Nullable Map<String, Object> attributes;
 
 		private @Nullable Object bodyValue;
@@ -347,6 +356,20 @@ public class HttpRequestValues {
 			return this;
 		}
 
+		/**
+		 * Set an API version for the request. The version is passed on to the
+		 * underlying {@code RestClient} or {@code WebClient} that in turn are
+		 * configured with an {@code ApiVersionInserter}.
+		 * @param version the API version of the request; this can be a String or
+		 * some Object that can be formatted the inserter, e.g. through an
+		 * {@link org.springframework.web.client.ApiVersionFormatter}.
+		 * @since 7.0
+		 */
+		public Builder setApiVersion(Object version) {
+			this.version = version;
+			return this;
+		}
+
 		/**
 		 * Configure an attribute to associate with the request.
 		 * @param name the attribute name
@@ -439,7 +462,7 @@ public class HttpRequestValues {
 
 			return createRequestValues(
 					this.httpMethod, uri, uriBuilderFactory, uriTemplate, uriVars,
-					headers, cookies, attributes, bodyValue);
+					headers, cookies, this.version, attributes, bodyValue);
 		}
 
 		protected boolean hasParts() {
@@ -484,12 +507,12 @@ public class HttpRequestValues {
 				@Nullable HttpMethod httpMethod,
 				@Nullable URI uri, @Nullable UriBuilderFactory uriBuilderFactory, @Nullable String uriTemplate,
 				Map<String, String> uriVars,
-				HttpHeaders headers, MultiValueMap<String, String> cookies, Map<String, Object> attributes,
-				@Nullable Object bodyValue) {
+				HttpHeaders headers, MultiValueMap<String, String> cookies, @Nullable Object version,
+				Map<String, Object> attributes, @Nullable Object bodyValue) {
 
 			return new HttpRequestValues(
 					this.httpMethod, uri, uriBuilderFactory, uriTemplate,
-					uriVars, headers, cookies, attributes, bodyValue);
+					uriVars, headers, cookies, version, attributes, bodyValue);
 		}
 	}
 

spring-web/src/main/java/org/springframework/web/service/invoker/HttpServiceMethod.java

@@ -158,7 +158,7 @@ final class HttpServiceMethod {
 	private record HttpRequestValuesInitializer(
 			@Nullable HttpMethod httpMethod, @Nullable String url,
 			@Nullable MediaType contentType, @Nullable List<MediaType> acceptMediaTypes,
-			MultiValueMap<String, String> headers,
+			MultiValueMap<String, String> headers, @Nullable String version,
 			Supplier<HttpRequestValues.Builder> requestValuesSupplier) {
 
 		public HttpRequestValues.Builder initializeRequestValuesBuilder() {
@@ -177,6 +177,9 @@ final class HttpServiceMethod {
 			}
 			this.headers.forEach((name, values) ->
 					values.forEach(value -> requestValues.addHeader(name, value)));
+			if (this.version != null) {
+				requestValues.setApiVersion(this.version);
+			}
 			return requestValues;
 		}
 
@@ -208,9 +211,11 @@ final class HttpServiceMethod {
 			MediaType contentType = initContentType(typeAnnotation, methodAnnotation);
 			List<MediaType> acceptableMediaTypes = initAccept(typeAnnotation, methodAnnotation);
 			MultiValueMap<String, String> headers = initHeaders(typeAnnotation, methodAnnotation, embeddedValueResolver);
+			String version = initVersion(typeAnnotation, methodAnnotation);
 
 			return new HttpRequestValuesInitializer(
-					httpMethod, url, contentType, acceptableMediaTypes, headers, requestValuesSupplier);
+					httpMethod, url, contentType, acceptableMediaTypes, headers, version,
+					requestValuesSupplier);
 		}
 
 		private static @Nullable HttpMethod initHttpMethod(@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
@@ -254,7 +259,9 @@ final class HttpServiceMethod {
 			return (hasMethodLevelUrl ? methodLevelUrl : typeLevelUrl);
 		}
 
-		private static @Nullable MediaType initContentType(@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
+		private static @Nullable MediaType initContentType(
+				@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
+
 			String methodLevelContentType = methodAnnotation.contentType();
 			if (StringUtils.hasText(methodLevelContentType)) {
 				return MediaType.parseMediaType(methodLevelContentType);
@@ -268,7 +275,9 @@ final class HttpServiceMethod {
 			return null;
 		}
 
-		private static @Nullable List<MediaType> initAccept(@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
+		private static @Nullable List<MediaType> initAccept(
+				@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
+
 			String[] methodLevelAccept = methodAnnotation.accept();
 			if (!ObjectUtils.isEmpty(methodLevelAccept)) {
 				return MediaType.parseMediaTypes(List.of(methodLevelAccept));
@@ -294,6 +303,18 @@ final class HttpServiceMethod {
 			return headers;
 		}
 
+		private static @Nullable String initVersion(
+				@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation) {
+
+			if (StringUtils.hasText(methodAnnotation.version())) {
+				return methodAnnotation.version();
+			}
+			if (typeAnnotation != null && StringUtils.hasText(typeAnnotation.version())) {
+				return typeAnnotation.version();
+			}
+			return null;
+		}
+
 		private static void addHeaders(
 				String[] rawValues, @Nullable StringValueResolver embeddedValueResolver,
 				MultiValueMap<String, String> outputHeaders) {

spring-web/src/main/java/org/springframework/web/service/invoker/ReactiveHttpRequestValues.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -50,10 +50,12 @@ public final class ReactiveHttpRequestValues extends HttpRequestValues {
 			@Nullable HttpMethod httpMethod,
 			@Nullable URI uri, @Nullable UriBuilderFactory uriBuilderFactory,
 			@Nullable String uriTemplate, Map<String, String> uriVars,
-			HttpHeaders headers, MultiValueMap<String, String> cookies, Map<String, Object> attributes,
-			@Nullable Object bodyValue, @Nullable Publisher<?> body, @Nullable ParameterizedTypeReference<?> elementType) {
+			HttpHeaders headers, MultiValueMap<String, String> cookies, @Nullable Object version,
+			Map<String, Object> attributes,
+			@Nullable Object bodyValue, @Nullable Publisher<?> body,
+			@Nullable ParameterizedTypeReference<?> elementType) {
 
-		super(httpMethod, uri, uriBuilderFactory, uriTemplate, uriVars, headers, cookies, attributes, bodyValue);
+		super(httpMethod, uri, uriBuilderFactory, uriTemplate, uriVars, headers, cookies, version, attributes, bodyValue);
 		this.body = body;
 		this.bodyElementType = elementType;
 	}
@@ -232,12 +234,12 @@ public final class ReactiveHttpRequestValues extends HttpRequestValues {
 				@Nullable HttpMethod httpMethod,
 				@Nullable URI uri, @Nullable UriBuilderFactory uriBuilderFactory,
 				@Nullable String uriTemplate, Map<String, String> uriVars,
-				HttpHeaders headers, MultiValueMap<String, String> cookies, Map<String, Object> attributes,
-				@Nullable Object bodyValue) {
+				HttpHeaders headers, MultiValueMap<String, String> cookies, @Nullable Object version,
+				Map<String, Object> attributes, @Nullable Object bodyValue) {
 
 			return new ReactiveHttpRequestValues(
 					httpMethod, uri, uriBuilderFactory, uriTemplate, uriVars,
-					headers, cookies, attributes, bodyValue, this.body, this.bodyElementType);
+					headers, cookies, version, attributes, bodyValue, this.body, this.bodyElementType);
 		}
 	}
 

spring-web/src/test/java/org/springframework/web/client/RestClientVersionTests.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2002-2025 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client;
+
+import java.io.IOException;
+import java.util.function.Consumer;
+
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import okhttp3.mockwebserver.RecordedRequest;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.client.JdkClientHttpRequestFactory;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+
+/**
+ * {@link RestClient} tests for sending API versions.
+ * @author Rossen Stoyanchev
+ */
+public class RestClientVersionTests {
+
+	private final MockWebServer server = new MockWebServer();
+
+	private final RestClient.Builder restClientBuilder = RestClient.builder()
+			.requestFactory(new JdkClientHttpRequestFactory())
+			.baseUrl(this.server.url("/").toString());
+
+
+	@BeforeEach
+	void setUp() {
+		MockResponse response = new MockResponse();
+		response.setHeader("Content-Type", "text/plain").setBody("body");
+		this.server.enqueue(response);
+	}
+
+	@AfterEach
+	void shutdown() throws IOException {
+		this.server.shutdown();
+	}
+
+
+	@Test
+	void header() {
+		performRequest(DefaultApiVersionInserter.fromHeader("X-API-Version"));
+		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
+	}
+
+	@Test
+	void queryParam() {
+		performRequest(DefaultApiVersionInserter.fromQueryParam("api-version"));
+		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path?api-version=1.2"));
+	}
+
+	@Test
+	void pathSegmentIndexLessThanSize() {
+		performRequest(DefaultApiVersionInserter.fromPathSegment(0).withVersionFormatter(v -> "v" + v));
+		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/v1.2/path"));
+	}
+
+	@Test
+	void pathSegmentIndexEqualToSize() {
+		performRequest(DefaultApiVersionInserter.fromPathSegment(1).withVersionFormatter(v -> "v" + v));
+		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path/v1.2"));
+	}
+
+	@Test
+	void pathSegmentIndexGreaterThanSize() {
+		assertThatIllegalStateException()
+				.isThrownBy(() -> performRequest(DefaultApiVersionInserter.fromPathSegment(2)))
+				.withMessage("Cannot insert version into '/path' at path segment index 2");
+		}
+
+	private void performRequest(DefaultApiVersionInserter.Builder builder) {
+		ApiVersionInserter versionInserter = builder.build();
+		RestClient restClient = restClientBuilder.apiVersionInserter(versionInserter).build();
+
+		restClient.get()
+				.uri("/path")
+				.apiVersion(1.2)
+				.retrieve()
+				.body(String.class);
+	}
+
+	private void expectRequest(Consumer<RecordedRequest> consumer) {
+		try {
+			consumer.accept(this.server.takeRequest());
+		}
+		catch (InterruptedException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+}

spring-web/src/test/java/org/springframework/web/client/support/RestClientAdapterTests.java

@@ -32,6 +32,7 @@ import okhttp3.mockwebserver.MockWebServer;
 import okhttp3.mockwebserver.RecordedRequest;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
 
@@ -46,6 +47,7 @@ import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RequestPart;
+import org.springframework.web.client.DefaultApiVersionInserter;
 import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.multipart.MultipartFile;
@@ -266,6 +268,22 @@ class RestClientAdapterTests {
 		assertThat(this.anotherServer.getRequestCount()).isEqualTo(0);
 	}
 
+	@Test
+	void apiVersion() throws Exception {
+		RestClient restClient = RestClient.builder()
+				.baseUrl(anotherServer.url("/").toString())
+				.apiVersionInserter(DefaultApiVersionInserter.fromHeader("X-API-Version").build())
+				.build();
+
+		RestClientAdapter adapter = RestClientAdapter.create(restClient);
+		Service service = HttpServiceProxyFactory.builderFor(adapter).build().createClient(Service.class);
+
+		service.getGreetingWithVersion();
+
+		RecordedRequest request = anotherServer.takeRequest();
+		assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2");
+	}
+
 
 	private static MockWebServer anotherServer() {
 		MockWebServer server = new MockWebServer();
@@ -287,6 +305,9 @@ class RestClientAdapterTests {
 		@GetExchange("/greeting/{id}")
 		Optional<String> getGreetingWithDynamicUri(@Nullable URI uri, @PathVariable String id);
 
+		@GetExchange(url = "/greeting", version = "1.2")
+		String getGreetingWithVersion();
+
 		@PostExchange("/greeting")
 		void postWithHeader(@RequestHeader("testHeaderName") String testHeader, @RequestBody String requestBody);
 

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

@@ -52,6 +52,7 @@ import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.ApiVersionInserter;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.BodyInserter;
 import org.springframework.web.reactive.function.BodyInserters;
@@ -93,6 +94,8 @@ final class DefaultWebClient implements WebClient {
 
 	private final @Nullable MultiValueMap<String, String> defaultCookies;
 
+	private final @Nullable ApiVersionInserter apiVersionInserter;
+
 	private final @Nullable Consumer<RequestHeadersSpec<?>> defaultRequest;
 
 	private final List<DefaultResponseSpec.StatusHandler> defaultStatusHandlers;
@@ -106,7 +109,9 @@ final class DefaultWebClient implements WebClient {
 
 	DefaultWebClient(ExchangeFunction exchangeFunction, @Nullable ExchangeFilterFunction filterFunctions,
 			UriBuilderFactory uriBuilderFactory, @Nullable HttpHeaders defaultHeaders,
-			@Nullable MultiValueMap<String, String> defaultCookies, @Nullable Consumer<RequestHeadersSpec<?>> defaultRequest,
+			@Nullable MultiValueMap<String, String> defaultCookies,
+			@Nullable ApiVersionInserter apiVersionInserter,
+			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest,
 			@Nullable Map<Predicate<HttpStatusCode>, Function<ClientResponse, Mono<? extends Throwable>>> statusHandlerMap,
 			ObservationRegistry observationRegistry, @Nullable ClientRequestObservationConvention observationConvention,
 			DefaultWebClientBuilder builder) {
@@ -116,6 +121,7 @@ final class DefaultWebClient implements WebClient {
 		this.uriBuilderFactory = uriBuilderFactory;
 		this.defaultHeaders = defaultHeaders;
 		this.defaultCookies = defaultCookies;
+		this.apiVersionInserter = apiVersionInserter;
 		this.defaultRequest = defaultRequest;
 		this.defaultStatusHandlers = initStatusHandlers(statusHandlerMap);
 		this.observationRegistry = observationRegistry;
@@ -205,6 +211,8 @@ final class DefaultWebClient implements WebClient {
 
 		private @Nullable MultiValueMap<String, String> cookies;
 
+		private @Nullable Object apiVersion;
+
 		private @Nullable BodyInserter<?, ? super ClientHttpRequest> inserter;
 
 		private final Map<String, Object> attributes = new LinkedHashMap<>(4);
@@ -323,6 +331,12 @@ final class DefaultWebClient implements WebClient {
 			return this;
 		}
 
+		@Override
+		public DefaultRequestBodyUriSpec apiVersion(Object version) {
+			this.apiVersion = version;
+			return this;
+		}
+
 		@Override
 		public RequestBodySpec attribute(String name, Object value) {
 			this.attributes.put(name, value);
@@ -474,7 +488,12 @@ final class DefaultWebClient implements WebClient {
 		}
 
 		private URI initUri() {
-			return (this.uri != null ? this.uri : uriBuilderFactory.expand(""));
+			URI uriToUse = (this.uri != null ? this.uri : uriBuilderFactory.expand(""));
+			if (this.apiVersion != null) {
+				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
+				uriToUse = apiVersionInserter.insertVersion(this.apiVersion, uriToUse);
+			}
+			return uriToUse;
 		}
 
 		private void initHeaders(HttpHeaders out) {
@@ -484,6 +503,10 @@ final class DefaultWebClient implements WebClient {
 			if (this.headers != null && !this.headers.isEmpty()) {
 				out.putAll(this.headers);
 			}
+			if (this.apiVersion != null) {
+				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
+				apiVersionInserter.insertVersion(this.apiVersion, out);
+			}
 		}
 
 		private void initCookies(MultiValueMap<String, String> out) {

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

@@ -42,6 +42,7 @@ import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.ApiVersionInserter;
 import org.springframework.web.util.DefaultUriBuilderFactory;
 import org.springframework.web.util.UriBuilderFactory;
 
@@ -80,6 +81,8 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 
 	private @Nullable MultiValueMap<String, String> defaultCookies;
 
+	private @Nullable ApiVersionInserter apiVersionInserter;
+
 	private @Nullable Consumer<WebClient.RequestHeadersSpec<?>> defaultRequest;
 
 	private @Nullable Map<Predicate<HttpStatusCode>, Function<ClientResponse, Mono<? extends Throwable>>> statusHandlers;
@@ -118,8 +121,9 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 			this.defaultHeaders = null;
 		}
 
-		this.defaultCookies = (other.defaultCookies != null ?
-				new LinkedMultiValueMap<>(other.defaultCookies) : null);
+		this.defaultCookies = (other.defaultCookies != null ? new LinkedMultiValueMap<>(other.defaultCookies) : null);
+		this.apiVersionInserter = other.apiVersionInserter;
+
 		this.defaultRequest = other.defaultRequest;
 		this.statusHandlers = (other.statusHandlers != null ? new LinkedHashMap<>(other.statusHandlers) : null);
 		this.filters = (other.filters != null ? new ArrayList<>(other.filters) : null);
@@ -190,6 +194,13 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 		return this.defaultCookies;
 	}
 
+
+	@Override
+	public WebClient.Builder apiVersionInserter(ApiVersionInserter apiVersionInserter) {
+		this.apiVersionInserter = apiVersionInserter;
+		return this;
+	}
+
 	@Override
 	public WebClient.Builder defaultRequest(Consumer<WebClient.RequestHeadersSpec<?>> defaultRequest) {
 		this.defaultRequest = this.defaultRequest != null ?
@@ -297,6 +308,7 @@ final class DefaultWebClientBuilder implements WebClient.Builder {
 		return new DefaultWebClient(
 				exchange, filterFunctions,
 				initUriBuilderFactory(), defaultHeaders, defaultCookies,
+				this.apiVersionInserter,
 				this.defaultRequest,
 				this.statusHandlers,
 				this.observationRegistry, this.observationConvention,

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

@@ -45,6 +45,8 @@ import org.springframework.http.client.reactive.ClientHttpRequest;
 import org.springframework.http.client.reactive.ClientHttpResponse;
 import org.springframework.http.codec.ClientCodecConfigurer;
 import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.ApiVersionFormatter;
+import org.springframework.web.client.ApiVersionInserter;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.BodyInserter;
 import org.springframework.web.reactive.function.BodyInserters;
@@ -250,6 +252,15 @@ public interface WebClient {
 		 */
 		Builder defaultCookies(Consumer<MultiValueMap<String, String>> cookiesConsumer);
 
+		/**
+		 * Configure an {@link ApiVersionInserter} to abstract how an API version
+		 * specified via {@link RequestHeadersSpec#apiVersion(Object)}
+		 * is inserted into the request.
+		 * @param apiVersionInserter the inserter to use
+		 * @since 7.0
+		 */
+		Builder apiVersionInserter(ApiVersionInserter apiVersionInserter);
+
 		/**
 		 * Provide a consumer to customize every request being built.
 		 * @param defaultRequest the consumer to use for modifying requests
@@ -475,6 +486,17 @@ public interface WebClient {
 		 */
 		S headers(Consumer<HttpHeaders> headersConsumer);
 
+		/**
+		 * Set an API version for the request. The version is inserted into the
+		 * request by the {@link Builder#apiVersionInserter(ApiVersionInserter)
+		 * configured} {@code ApiVersionInserter}.
+		 * @param version the API version of the request; this can be a String or
+		 * some Object that can be formatted the inserter, e.g. through an
+		 * {@link ApiVersionFormatter}.
+		 * @since 7.0
+		 */
+		S apiVersion(Object version);
+
 		/**
 		 * Set the attribute with the given name to the given value.
 		 * @param name the name of the attribute to add

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -127,6 +127,11 @@ public final class WebClientAdapter extends AbstractReactorHttpExchangeAdapter {
 
 		bodySpec.headers(headers -> headers.putAll(values.getHeaders()));
 		bodySpec.cookies(cookies -> cookies.putAll(values.getCookies()));
+
+		if (values.getApiVersion() != null) {
+			bodySpec.apiVersion(values.getApiVersion());
+		}
+
 		bodySpec.attributes(attributes -> attributes.putAll(values.getAttributes()));
 
 		if (values.getBodyValue() != null) {