Add defaultApiVersion to RestClient and WebClient

Closes gh-34857

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 Object defaultApiVersion;
+
 	private final @Nullable ApiVersionInserter apiVersionInserter;
 
 	private final @Nullable Consumer<RequestHeadersSpec<?>> defaultRequest;
@@ -130,7 +132,7 @@ final class DefaultRestClient implements RestClient {
 			UriBuilderFactory uriBuilderFactory,
 			@Nullable HttpHeaders defaultHeaders,
 			@Nullable MultiValueMap<String, String> defaultCookies,
-			@Nullable ApiVersionInserter apiVersionInserter,
+			@Nullable Object defaultApiVersion, @Nullable ApiVersionInserter apiVersionInserter,
 			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest,
 			@Nullable List<StatusHandler> statusHandlers,
 			List<HttpMessageConverter<?>> messageConverters,
@@ -145,6 +147,7 @@ final class DefaultRestClient implements RestClient {
 		this.uriBuilderFactory = uriBuilderFactory;
 		this.defaultHeaders = defaultHeaders;
 		this.defaultCookies = defaultCookies;
+		this.defaultApiVersion = defaultApiVersion;
 		this.apiVersionInserter = apiVersionInserter;
 		this.defaultRequest = defaultRequest;
 		this.defaultStatusHandlers = (statusHandlers != null ? new ArrayList<>(statusHandlers) : new ArrayList<>());
@@ -609,13 +612,18 @@ final class DefaultRestClient implements RestClient {
 
 		private URI initUri() {
 			URI uriToUse = this.uri != null ? this.uri : DefaultRestClient.this.uriBuilderFactory.expand("");
-			if (this.apiVersion != null) {
+			Object version = getApiVersionOrDefault();
+			if (version != null) {
 				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
-				uriToUse = apiVersionInserter.insertVersion(this.apiVersion, uriToUse);
+				uriToUse = apiVersionInserter.insertVersion(version, uriToUse);
 			}
 			return uriToUse;
 		}
 
+		private @Nullable Object getApiVersionOrDefault() {
+			return (this.apiVersion != null ? this.apiVersion : DefaultRestClient.this.defaultApiVersion);
+		}
+
 		private @Nullable String serializeCookies() {
 			MultiValueMap<String, String> map;
 			MultiValueMap<String, String> defaultCookies = DefaultRestClient.this.defaultCookies;
@@ -652,7 +660,8 @@ final class DefaultRestClient implements RestClient {
 
 		private @Nullable HttpHeaders initHeaders() {
 			HttpHeaders defaultHeaders = DefaultRestClient.this.defaultHeaders;
-			if (this.apiVersion == null) {
+			Object version = getApiVersionOrDefault();
+			if (version == null) {
 				if (this.headers == null || this.headers.isEmpty()) {
 					return defaultHeaders;
 				}
@@ -669,9 +678,9 @@ final class DefaultRestClient implements RestClient {
 				result.putAll(this.headers);
 			}
 
-			if (this.apiVersion != null) {
+			if (version != null) {
 				Assert.state(apiVersionInserter != null, "No ApiVersionInserter configured");
-				apiVersionInserter.insertVersion(this.apiVersion, result);
+				apiVersionInserter.insertVersion(version, result);
 			}
 
 			return result;

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

@@ -116,7 +116,6 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 
 	private static final boolean kotlinSerializationProtobufPresent;
 
-
 	static {
 		ClassLoader loader = DefaultRestClientBuilder.class.getClassLoader();
 
@@ -150,6 +149,8 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 
 	private @Nullable MultiValueMap<String, String> defaultCookies;
 
+	private @Nullable Object defaultApiVersion;
+
 	private @Nullable ApiVersionInserter apiVersionInserter;
 
 	private @Nullable Consumer<RestClient.RequestHeadersSpec<?>> defaultRequest;
@@ -188,6 +189,7 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 			this.defaultHeaders = null;
 		}
 		this.defaultCookies = (other.defaultCookies != null ? new LinkedMultiValueMap<>(other.defaultCookies) : null);
+		this.defaultApiVersion = other.defaultApiVersion;
 		this.apiVersionInserter = other.apiVersionInserter;
 		this.defaultRequest = other.defaultRequest;
 		this.statusHandlers = (other.statusHandlers != null ? new ArrayList<>(other.statusHandlers) : null);
@@ -324,6 +326,12 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 		return this.defaultCookies;
 	}
 
+	@Override
+	public RestClient.Builder defaultApiVersion(@Nullable Object version) {
+		this.defaultApiVersion = version;
+		return this;
+	}
+
 	@Override
 	public RestClient.Builder apiVersionInserter(ApiVersionInserter apiVersionInserter) {
 		this.apiVersionInserter = apiVersionInserter;
@@ -521,7 +529,7 @@ final class DefaultRestClientBuilder implements RestClient.Builder {
 
 		return new DefaultRestClient(
 				requestFactory, this.interceptors, this.bufferingPredicate, this.initializers,
-				uriBuilderFactory, defaultHeaders, defaultCookies,
+				uriBuilderFactory, defaultHeaders, defaultCookies, this.defaultApiVersion,
 				this.apiVersionInserter, this.defaultRequest,
 				this.statusHandlers, converters,
 				this.observationRegistry, this.observationConvention,

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);
 
+		/**
+		 * Global option to specify an API version to be added to every request,
+		 * if not explicitly set.
+		 * @param version the version to use
+		 * @return this builder
+		 * @since 7.0
+		 */
+		Builder defaultApiVersion(Object version);
+
 		/**
 		 * Configure an {@link ApiVersionInserter} to abstract how an API version
 		 * specified via {@link RequestHeadersSpec#apiVersion(Object)}

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

@@ -86,7 +86,16 @@ public class RestClientVersionTests {
 		assertThatIllegalStateException()
 				.isThrownBy(() -> performRequest(DefaultApiVersionInserter.fromPathSegment(2)))
 				.withMessage("Cannot insert version into '/path' at path segment index 2");
-		}
+	}
+
+	@Test
+	void defaultVersion() {
+		ApiVersionInserter inserter = DefaultApiVersionInserter.fromHeader("X-API-Version").build();
+		RestClient restClient = restClientBuilder.defaultApiVersion(1.2).apiVersionInserter(inserter).build();
+		restClient.get().uri("/path").retrieve().body(String.class);
+
+		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
+	}
 
 	private void performRequest(DefaultApiVersionInserter.Builder builder) {
 		ApiVersionInserter versionInserter = builder.build();