Support for functional routing by API version

See gh-35113

spring-test/src/main/java/org/springframework/mock/web/reactive/function/server/MockServerRequest.java

@@ -50,6 +50,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.WebDataBinder;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.server.HandlerStrategies;
 import org.springframework.web.reactive.function.server.ServerRequest;
@@ -94,6 +95,8 @@ public final class MockServerRequest implements ServerRequest {
 
 	private final List<HttpMessageReader<?>> messageReaders;
 
+	private final @Nullable ApiVersionStrategy versionStrategy;
+
 	private final @Nullable ServerWebExchange exchange;
 
 
@@ -102,7 +105,8 @@ public final class MockServerRequest implements ServerRequest {
 			Map<String, Object> attributes, MultiValueMap<String, String> queryParams,
 			Map<String, String> pathVariables, @Nullable WebSession session, @Nullable Principal principal,
 			@Nullable InetSocketAddress remoteAddress, @Nullable InetSocketAddress localAddress,
-			List<HttpMessageReader<?>> messageReaders, @Nullable ServerWebExchange exchange) {
+			List<HttpMessageReader<?>> messageReaders, @Nullable ApiVersionStrategy versionStrategy,
+			@Nullable ServerWebExchange exchange) {
 
 		this.method = method;
 		this.uri = uri;
@@ -118,6 +122,7 @@ public final class MockServerRequest implements ServerRequest {
 		this.remoteAddress = remoteAddress;
 		this.localAddress = localAddress;
 		this.messageReaders = messageReaders;
+		this.versionStrategy = versionStrategy;
 		this.exchange = exchange;
 	}
 
@@ -167,6 +172,11 @@ public final class MockServerRequest implements ServerRequest {
 		return this.messageReaders;
 	}
 
+	@Override
+	public @Nullable ApiVersionStrategy apiVersionStrategy() {
+		return this.versionStrategy;
+	}
+
 	@Override
 	@SuppressWarnings("unchecked")
 	public <S> S body(BodyExtractor<S, ? super ServerHttpRequest> extractor) {
@@ -313,6 +323,8 @@ public final class MockServerRequest implements ServerRequest {
 
 		Builder messageReaders(List<HttpMessageReader<?>> messageReaders);
 
+		Builder apiVersionStrategy(@Nullable ApiVersionStrategy versionStrategy);
+
 		Builder exchange(ServerWebExchange exchange);
 
 		MockServerRequest body(Object body);
@@ -351,6 +363,8 @@ public final class MockServerRequest implements ServerRequest {
 
 		private List<HttpMessageReader<?>> messageReaders = HandlerStrategies.withDefaults().messageReaders();
 
+		private @Nullable ApiVersionStrategy versionStrategy;
+
 		private @Nullable ServerWebExchange exchange;
 
 		@Override
@@ -483,6 +497,12 @@ public final class MockServerRequest implements ServerRequest {
 			return this;
 		}
 
+		@Override
+		public Builder apiVersionStrategy(@Nullable ApiVersionStrategy versionStrategy) {
+			this.versionStrategy = versionStrategy;
+			return this;
+		}
+
 		@Override
 		public Builder exchange(ServerWebExchange exchange) {
 			Assert.notNull(exchange, "'exchange' must not be null");
@@ -496,7 +516,7 @@ public final class MockServerRequest implements ServerRequest {
 			return new MockServerRequest(this.method, this.uri, this.contextPath, this.headers,
 					this.cookies, this.body, this.attributes, this.queryParams, this.pathVariables,
 					this.session, this.principal, this.remoteAddress, this.localAddress,
-					this.messageReaders, this.exchange);
+					this.messageReaders, this.versionStrategy, this.exchange);
 		}
 
 		@Override
@@ -504,7 +524,7 @@ public final class MockServerRequest implements ServerRequest {
 			return new MockServerRequest(this.method, this.uri, this.contextPath, this.headers,
 					this.cookies, null, this.attributes, this.queryParams, this.pathVariables,
 					this.session, this.principal, this.remoteAddress, this.localAddress,
-					this.messageReaders, this.exchange);
+					this.messageReaders, this.versionStrategy, this.exchange);
 		}
 	}
 

spring-web/src/main/java/org/springframework/web/accept/DefaultApiVersionStrategy.java

@@ -91,6 +91,16 @@ public class DefaultApiVersionStrategy implements ApiVersionStrategy {
 		return this.defaultVersion;
 	}
 
+	/**
+	 * Whether the strategy is configured to detect supported versions.
+	 * If this is set to {@code false} then {@link #addMappedVersion} is ignored
+	 * and the list of supported versions can be built explicitly through calls
+	 * to {@link #addSupportedVersion}.
+	 */
+	public boolean detectSupportedVersions() {
+		return this.detectSupportedVersions;
+	}
+
 	/**
 	 * Add to the list of supported versions to check against in
 	 * {@link ApiVersionStrategy#validateVersion} before raising

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurationSupport.java

@@ -246,10 +246,13 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 	}
 
 	@Bean
-	public RouterFunctionMapping routerFunctionMapping(ServerCodecConfigurer serverCodecConfigurer) {
+	public RouterFunctionMapping routerFunctionMapping(
+			ServerCodecConfigurer serverCodecConfigurer, @Nullable ApiVersionStrategy apiVersionStrategy) {
+
 		RouterFunctionMapping mapping = createRouterFunctionMapping();
 		mapping.setOrder(-1);  // go before RequestMappingHandlerMapping
 		mapping.setMessageReaders(serverCodecConfigurer.getReaders());
+		mapping.setApiVersionStrategy(apiVersionStrategy);
 		configureAbstractHandlerMapping(mapping, getPathMatchConfigurer());
 		return mapping;
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequest.java

@@ -57,6 +57,7 @@ import org.springframework.validation.BindException;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.support.WebExchangeDataBinder;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.BodyExtractors;
 import org.springframework.web.reactive.function.UnsupportedMediaTypeException;
@@ -92,10 +93,20 @@ class DefaultServerRequest implements ServerRequest {
 
 	private final List<HttpMessageReader<?>> messageReaders;
 
+	private final @Nullable ApiVersionStrategy versionStrategy;
+
 
 	DefaultServerRequest(ServerWebExchange exchange, List<HttpMessageReader<?>> messageReaders) {
+		this(exchange, messageReaders, null);
+	}
+
+	DefaultServerRequest(
+			ServerWebExchange exchange, List<HttpMessageReader<?>> messageReaders,
+			@Nullable ApiVersionStrategy versionStrategy) {
+
 		this.exchange = exchange;
 		this.messageReaders = List.copyOf(messageReaders);
+		this.versionStrategy = versionStrategy;
 		this.headers = new DefaultHeaders();
 	}
 
@@ -162,6 +173,11 @@ class DefaultServerRequest implements ServerRequest {
 		return this.messageReaders;
 	}
 
+	@Override
+	public @Nullable ApiVersionStrategy apiVersionStrategy() {
+		return this.versionStrategy;
+	}
+
 	@Override
 	public <T> T body(BodyExtractor<T, ? super ServerHttpRequest> extractor) {
 		return bodyInternal(extractor, Hints.from(Hints.LOG_PREFIX_HINT, exchange().getLogPrefix()));

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequestBuilder.java

@@ -54,6 +54,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebSession;
 import org.springframework.web.util.UriUtils;
@@ -69,6 +70,8 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 	private final List<HttpMessageReader<?>> messageReaders;
 
+	private final @Nullable ApiVersionStrategy versionStrategy;
+
 	private final ServerWebExchange exchange;
 
 	private HttpMethod method;
@@ -89,6 +92,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 	DefaultServerRequestBuilder(ServerRequest other) {
 		Assert.notNull(other, "ServerRequest must not be null");
 		this.messageReaders = other.messageReaders();
+		this.versionStrategy = other.apiVersionStrategy();
 		this.exchange = other.exchange();
 		this.method = other.method();
 		this.uri = other.uri();
@@ -195,7 +199,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 				this.method, this.uri, this.contextPath, this.headers, this.cookies, this.body, this.attributes);
 		ServerWebExchange exchange = new DelegatingServerWebExchange(
 				serverHttpRequest, this.attributes, this.exchange, this.messageReaders);
-		return new DefaultServerRequest(exchange, this.messageReaders);
+		return new DefaultServerRequest(exchange, this.messageReaders, this.versionStrategy);
 	}
 
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RequestPredicates.java

@@ -54,6 +54,8 @@ import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.cors.reactive.CorsUtils;
+import org.springframework.web.reactive.HandlerMapping;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebSession;
@@ -182,6 +184,25 @@ public abstract class RequestPredicates {
 		}
 	}
 
+	/**
+	 * {@code RequestPredicate} to match to the request API version extracted
+	 * from and parsed with the configured {@link ApiVersionStrategy}.
+	 * <p>The version may be one of the following:
+	 * <ul>
+	 * <li>Fixed version ("1.2") -- match this version only.
+	 * <li>Baseline version ("1.2+") -- match this and subsequent versions.
+	 * </ul>
+	 * <p>A baseline version allows n endpoint route to continue to work in
+	 * subsequent versions if it remains compatible until an incompatible change
+	 * eventually leads to the creation of a new route.
+	 * @param version the version to use
+	 * @return the created predicate instance
+	 * @since 7.0
+	 */
+	public static RequestPredicate version(Object version) {
+		return new ApiVersionPredicate(version);
+	}
+
 	/**
 	 * Return a {@code RequestPredicate} that matches if request's HTTP method is {@code GET}
 	 * and the given {@code pattern} matches against the request path.
@@ -390,6 +411,14 @@ public abstract class RequestPredicates {
 		 */
 		void queryParam(String name, String value);
 
+		/**
+		 * Receive notification of an API version predicate. The version could
+		 * be fixed ("1.2") or baseline ("1.2+").
+		 * @param version the configured version
+		 * @since 7.0
+		 */
+		void version(String version);
+
 		/**
 		 * Receive first notification of a logical AND predicate.
 		 * The first subsequent notification will contain the left-hand side of the AND-predicate;
@@ -831,6 +860,69 @@ public abstract class RequestPredicates {
 	}
 
 
+	private static class ApiVersionPredicate implements RequestPredicate {
+
+		private final String version;
+
+		private final boolean baselineVersion;
+
+		private @Nullable Comparable<?> parsedVersion;
+
+		public ApiVersionPredicate(Object version) {
+			if (version instanceof String s) {
+				this.baselineVersion = s.endsWith("+");
+				this.version = initVersion(s, this.baselineVersion);
+			}
+			else {
+				this.baselineVersion = false;
+				this.version = version.toString();
+				this.parsedVersion = (Comparable<?>) version;
+			}
+		}
+
+		private static String initVersion(String version, boolean baselineVersion) {
+			return (baselineVersion ? version.substring(0, version.length() - 1) : version);
+		}
+
+		@Override
+		public boolean test(ServerRequest request) {
+			if (this.parsedVersion == null) {
+				ApiVersionStrategy strategy = request.apiVersionStrategy();
+				Assert.state(strategy != null, "No ApiVersionStrategy to parse version with");
+				this.parsedVersion = strategy.parseVersion(this.version);
+			}
+
+			Comparable<?> requestVersion =
+					(Comparable<?>) request.attribute(HandlerMapping.API_VERSION_ATTRIBUTE).orElse(null);
+
+			if (requestVersion == null) {
+				traceMatch("Version", this.version, null, true);
+				return true;
+			}
+
+			int result = compareVersions(this.parsedVersion, requestVersion);
+			boolean match = (this.baselineVersion ? result <= 0 : result == 0);
+			traceMatch("Version", this.version, requestVersion, match);
+			return match;
+		}
+
+		@SuppressWarnings("unchecked")
+		private <V extends Comparable<V>> int compareVersions(Object v1, Object v2) {
+			return ((V) v1).compareTo((V) v2);
+		}
+
+		@Override
+		public void accept(Visitor visitor) {
+			visitor.version(this.version + (this.baselineVersion ? "+" : ""));
+		}
+
+		@Override
+		public String toString() {
+			return this.version;
+		}
+	}
+
+
 	@Deprecated(since = "7.0", forRemoval = true)
 	private static class PathExtensionPredicate implements RequestPredicate {
 
@@ -1189,6 +1281,11 @@ public abstract class RequestPredicates {
 			return this.delegate.messageReaders();
 		}
 
+		@Override
+		public @Nullable ApiVersionStrategy apiVersionStrategy() {
+			return this.delegate.apiVersionStrategy();
+		}
+
 		@Override
 		public <T> T body(BodyExtractor<T, ? super ServerHttpRequest> extractor) {
 			return this.delegate.body(extractor);

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/ServerRequest.java

@@ -49,6 +49,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.MultiValueMap;
 import org.springframework.validation.BindException;
 import org.springframework.web.bind.WebDataBinder;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebSession;
@@ -130,6 +131,12 @@ public interface ServerRequest {
 	 */
 	List<HttpMessageReader<?>> messageReaders();
 
+	/**
+	 * Return the configured {@link ApiVersionStrategy}, or {@code null}.
+	 * @since 7.0
+	 */
+	@Nullable ApiVersionStrategy apiVersionStrategy();
+
 	/**
 	 * Extract the body with the given {@code BodyExtractor}.
 	 * @param extractor the {@code BodyExtractor} that reads from the request
@@ -424,6 +431,23 @@ public interface ServerRequest {
 		return new DefaultServerRequest(exchange, messageReaders);
 	}
 
+	/**
+	 * Create a new {@code ServerRequest} based on the given {@code ServerWebExchange} and
+	 * message readers.
+	 * @param exchange the exchange
+	 * @param messageReaders the message readers
+	 * @param versionStrategy a strategy to use to parse version
+	 * @return the created {@code ServerRequest}
+	 * @since 7.0
+	 */
+	static ServerRequest create(
+			ServerWebExchange exchange, List<HttpMessageReader<?>> messageReaders,
+			@Nullable ApiVersionStrategy versionStrategy) {
+
+		return new DefaultServerRequest(exchange, messageReaders, versionStrategy);
+	}
+
+
 	/**
 	 * Create a builder with the {@linkplain HttpMessageReader message readers},
 	 * method name, URI, headers, cookies, and attributes of the given request.

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/ToStringVisitor.java

@@ -119,6 +119,11 @@ class ToStringVisitor implements RouterFunctions.Visitor, RequestPredicates.Visi
 		this.builder.append(String.format("?%s == %s", name, value));
 	}
 
+	@Override
+	public void version(String version) {
+		this.builder.append(String.format("version: %s", version));
+	}
+
 	@Override
 	public void startAnd() {
 		this.builder.append('(');

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/support/RouterFunctionMapping.java

@@ -29,6 +29,8 @@ import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.observation.ServerRequestObservationContext;
 import org.springframework.util.CollectionUtils;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
+import org.springframework.web.reactive.accept.DefaultApiVersionStrategy;
 import org.springframework.web.reactive.function.server.HandlerFunction;
 import org.springframework.web.reactive.function.server.RouterFunction;
 import org.springframework.web.reactive.function.server.RouterFunctions;
@@ -54,6 +56,8 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 
 	private List<HttpMessageReader<?>> messageReaders = Collections.emptyList();
 
+	private @Nullable ApiVersionStrategy versionStrategy;
+
 
 	/**
 	 * Create an empty {@code RouterFunctionMapping}.
@@ -92,6 +96,16 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 		this.messageReaders = messageReaders;
 	}
 
+	/**
+	 * Configure a strategy to manage API versioning.
+	 * @param strategy the strategy to use
+	 * @since 7.0
+	 */
+	public void setApiVersionStrategy(@Nullable ApiVersionStrategy strategy) {
+		this.versionStrategy = strategy;
+	}
+
+
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		if (CollectionUtils.isEmpty(this.messageReaders)) {
@@ -102,8 +116,14 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 		if (this.routerFunction == null) {
 			initRouterFunctions();
 		}
+
 		if (this.routerFunction != null) {
 			RouterFunctions.changeParser(this.routerFunction, getPathPatternParser());
+			if (this.versionStrategy instanceof DefaultApiVersionStrategy davs) {
+				if (davs.detectSupportedVersions()) {
+					this.routerFunction.accept(new SupportedVersionVisitor(davs));
+				}
+			}
 		}
 
 	}
@@ -149,14 +169,26 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 
 	@Override
 	protected Mono<?> getHandlerInternal(ServerWebExchange exchange) {
-		if (this.routerFunction != null) {
+
-			ServerRequest request = ServerRequest.create(exchange, this.messageReaders);
+		if (this.routerFunction == null) {
-			return this.routerFunction.route(request)
-					.doOnNext(handler -> setAttributes(exchange.getAttributes(), request, handler));
-		}
-		else {
 			return Mono.empty();
 		}
+
+		if (this.versionStrategy != null) {
+			Comparable<?> version = exchange.getAttribute(API_VERSION_ATTRIBUTE);
+			if (version == null) {
+				version = this.versionStrategy.resolveParseAndValidateVersion(exchange);
+				if (version != null) {
+					exchange.getAttributes().put(API_VERSION_ATTRIBUTE, version);
+				}
+			}
+		}
+
+		ServerRequest request = ServerRequest.create(
+				exchange, this.messageReaders, this.versionStrategy);
+
+		return this.routerFunction.route(request)
+				.doOnNext(handler -> setAttributes(exchange.getAttributes(), request, handler));
 	}
 
 	@SuppressWarnings("unchecked")

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/support/ServerRequestWrapper.java

@@ -44,6 +44,7 @@ import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.util.Assert;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.WebDataBinder;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.server.ServerRequest;
 import org.springframework.web.server.ServerWebExchange;
@@ -131,6 +132,11 @@ public class ServerRequestWrapper implements ServerRequest {
 		return this.delegate.messageReaders();
 	}
 
+	@Override
+	public @Nullable ApiVersionStrategy apiVersionStrategy() {
+		return this.delegate.apiVersionStrategy();
+	}
+
 	@Override
 	public <T> T body(BodyExtractor<T, ? super ServerHttpRequest> extractor) {
 		return this.delegate.body(extractor);

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/support/SupportedVersionVisitor.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2002-present 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.reactive.function.server.support;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Function;
+
+import reactor.core.publisher.Mono;
+
+import org.springframework.core.io.Resource;
+import org.springframework.http.HttpMethod;
+import org.springframework.web.reactive.accept.DefaultApiVersionStrategy;
+import org.springframework.web.reactive.function.server.HandlerFunction;
+import org.springframework.web.reactive.function.server.RequestPredicate;
+import org.springframework.web.reactive.function.server.RequestPredicates;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.RouterFunctions;
+import org.springframework.web.reactive.function.server.ServerRequest;
+
+/**
+ * {@link RequestPredicates.Visitor} that discovers versions used in routes in
+ * order to add them to the list of supported versions.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ */
+final class SupportedVersionVisitor implements RouterFunctions.Visitor, RequestPredicates.Visitor {
+
+	private final DefaultApiVersionStrategy versionStrategy;
+
+
+	SupportedVersionVisitor(DefaultApiVersionStrategy versionStrategy) {
+		this.versionStrategy = versionStrategy;
+	}
+
+
+	// RouterFunctions.Visitor
+
+	@Override
+	public void startNested(RequestPredicate predicate) {
+		predicate.accept(this);
+	}
+
+	@Override
+	public void endNested(RequestPredicate predicate) {
+	}
+
+	@Override
+	public void route(RequestPredicate predicate, HandlerFunction<?> handlerFunction) {
+		predicate.accept(this);
+	}
+
+	@Override
+	public void resources(Function<ServerRequest, Mono<Resource>> lookupFunction) {
+	}
+
+	@Override
+	public void attributes(Map<String, Object> attributes) {
+	}
+
+	@Override
+	public void unknown(RouterFunction<?> routerFunction) {
+	}
+
+
+	// RequestPredicates.Visitor
+
+	@Override
+	public void method(Set<HttpMethod> methods) {
+	}
+
+	@Override
+	public void path(String pattern) {
+	}
+
+	@SuppressWarnings("removal")
+	@Override
+	public void pathExtension(String extension) {
+	}
+
+	@Override
+	public void header(String name, String value) {
+	}
+
+	@Override
+	public void queryParam(String name, String value) {
+	}
+
+	@Override
+	public void version(String version) {
+		this.versionStrategy.addMappedVersion(
+				(version.endsWith("+") ? version.substring(0, version.length() - 1) : version));
+	}
+
+	@Override
+	public void startAnd() {
+	}
+
+	@Override
+	public void and() {
+	}
+
+	@Override
+	public void endAnd() {
+	}
+
+	@Override
+	public void startOr() {
+	}
+
+	@Override
+	public void or() {
+	}
+
+	@Override
+	public void endOr() {
+	}
+
+	@Override
+	public void startNegate() {
+	}
+
+	@Override
+	public void endNegate() {
+	}
+
+	@Override
+	public void unknown(RequestPredicate predicate) {
+	}
+
+}

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/RequestPredicatesTests.java

@@ -26,6 +26,10 @@ import org.junit.jupiter.api.Test;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
+import org.springframework.web.accept.SemanticApiVersionParser;
+import org.springframework.web.reactive.HandlerMapping;
+import org.springframework.web.reactive.accept.ApiVersionStrategy;
+import org.springframework.web.reactive.accept.DefaultApiVersionStrategy;
 import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
 import org.springframework.web.testfixture.server.MockServerWebExchange;
 import org.springframework.web.util.pattern.PathPatternParser;
@@ -359,4 +363,24 @@ class RequestPredicatesTests {
 		assertThat(predicate.test(request)).isFalse();
 	}
 
+	@Test
+	void version() {
+		assertThat(RequestPredicates.version("1.1").test(serverRequest("1.1"))).isTrue();
+		assertThat(RequestPredicates.version("1.1+").test(serverRequest("1.5"))).isTrue();
+		assertThat(RequestPredicates.version("1.1").test(serverRequest("1.5"))).isFalse();
+	}
+
+	private static DefaultServerRequest serverRequest(String version) {
+		ApiVersionStrategy versionStrategy = apiVersionStrategy();
+		Comparable<?> parsedVersion = versionStrategy.parseVersion(version);
+		MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("https://localhost"));
+		exchange.getAttributes().put(HandlerMapping.API_VERSION_ATTRIBUTE, parsedVersion);
+		return new DefaultServerRequest(exchange, Collections.emptyList(), versionStrategy);
+	}
+
+	private static DefaultApiVersionStrategy apiVersionStrategy() {
+		return new DefaultApiVersionStrategy(
+				List.of(exchange -> null), new SemanticApiVersionParser(), true, null, false, null);
+	}
+
 }

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/support/RouterFunctionMappingVersionTests.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2002-present 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.reactive.function.server.support;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.reactive.config.ApiVersionConfigurer;
+import org.springframework.web.reactive.config.EnableWebFlux;
+import org.springframework.web.reactive.config.WebFluxConfigurer;
+import org.springframework.web.reactive.function.server.HandlerFunction;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.RouterFunctions;
+import org.springframework.web.reactive.function.server.ServerRequest;
+import org.springframework.web.reactive.function.server.ServerResponse;
+import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
+import org.springframework.web.testfixture.server.MockServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.web.reactive.function.server.RequestPredicates.version;
+
+/**
+ * {@link RouterFunctionMapping} integration tests for API versioning.
+ * @author Rossen Stoyanchev
+ */
+public class RouterFunctionMappingVersionTests {
+
+	private RouterFunctionMapping mapping;
+
+
+	@BeforeEach
+	void setUp() {
+		AnnotationConfigApplicationContext wac = new AnnotationConfigApplicationContext();
+		wac.register(WebConfig.class);
+		wac.refresh();
+
+		this.mapping = wac.getBean(RouterFunctionMapping.class);
+	}
+
+
+	@Test
+	void mapVersion() {
+		testGetHandler("1.0", "none");
+		testGetHandler("1.1", "none");
+		testGetHandler("1.2", "1.2");
+		testGetHandler("1.3", "1.2");
+		testGetHandler("1.5", "1.5");
+	}
+
+
+	private void testGetHandler(String version, String expectedBody) {
+
+		MockServerWebExchange exchange = MockServerWebExchange.from(
+				MockServerHttpRequest.get("/").header("X-API-Version", version));
+
+		Mono<?> result = this.mapping.getHandler(exchange);
+
+		StepVerifier.create(result)
+				.consumeNextWith(handler -> assertThat(((TestHandler) handler).body()).isEqualTo(expectedBody))
+				.verifyComplete();
+	}
+
+
+	@EnableWebFlux
+	private static class WebConfig implements WebFluxConfigurer {
+
+		@Override
+		public void configureApiVersioning(ApiVersionConfigurer configurer) {
+			configurer.useRequestHeader("X-API-Version").addSupportedVersions("1", "1.1", "1.3");
+		}
+
+		@Bean
+		RouterFunction<?> routerFunction() {
+			return RouterFunctions.route()
+					.path("/", builder -> builder
+							.GET(version("1.5"), new TestHandler("1.5"))
+							.GET(version("1.2+"), new TestHandler("1.2"))
+							.GET(new TestHandler("none")))
+					.build();
+		}
+	}
+
+
+	private record TestHandler(String body) implements HandlerFunction<ServerResponse> {
+
+		@Override
+		public Mono<ServerResponse> handle(ServerRequest request) {
+			return ServerResponse.ok().bodyValue(body);
+		}
+	}
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -544,13 +544,15 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	@Bean
 	public RouterFunctionMapping routerFunctionMapping(
 			@Qualifier("mvcConversionService") FormattingConversionService conversionService,
-			@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {
+			@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider,
+			@Qualifier("mvcApiVersionStrategy") @Nullable ApiVersionStrategy versionStrategy) {
 
 		RouterFunctionMapping mapping = new RouterFunctionMapping();
 		mapping.setOrder(-1);  // go before RequestMappingHandlerMapping
 		mapping.setInterceptors(getInterceptors(conversionService, resourceUrlProvider));
 		mapping.setCorsConfigurations(getCorsConfigurations());
 		mapping.setMessageConverters(getMessageConverters());
+		mapping.setApiVersionStrategy(versionStrategy);
 
 		PathPatternParser patternParser = getPathMatchConfigurer().getPatternParser();
 		if (patternParser != null) {

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequest.java

@@ -71,6 +71,7 @@ import org.springframework.util.ObjectUtils;
 import org.springframework.validation.BindException;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.HttpMediaTypeNotSupportedException;
+import org.springframework.web.accept.ApiVersionStrategy;
 import org.springframework.web.bind.ServletRequestDataBinder;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.context.request.ServletWebRequest;
@@ -97,6 +98,8 @@ class DefaultServerRequest implements ServerRequest {
 
 	private final List<HttpMessageConverter<?>> messageConverters;
 
+	private final @Nullable ApiVersionStrategy versionStrategy;
+
 	private final MultiValueMap<String, String> params;
 
 	private final Map<String, Object> attributes;
@@ -105,8 +108,16 @@ class DefaultServerRequest implements ServerRequest {
 
 
 	public DefaultServerRequest(HttpServletRequest servletRequest, List<HttpMessageConverter<?>> messageConverters) {
+		this(servletRequest, messageConverters, null);
+	}
+
+	public DefaultServerRequest(
+			HttpServletRequest servletRequest, List<HttpMessageConverter<?>> messageConverters,
+			@Nullable ApiVersionStrategy versionStrategy) {
+
 		this.serverHttpRequest = new ServletServerHttpRequest(servletRequest);
 		this.messageConverters = List.copyOf(messageConverters);
+		this.versionStrategy = versionStrategy;
 
 		this.headers = new DefaultRequestHeaders(this.serverHttpRequest.getHeaders());
 		this.params = CollectionUtils.toMultiValueMap(new ServletParametersMap(servletRequest));
@@ -172,6 +183,11 @@ class DefaultServerRequest implements ServerRequest {
 		return this.messageConverters;
 	}
 
+	@Override
+	public @Nullable ApiVersionStrategy apiVersionStrategy() {
+		return this.versionStrategy;
+	}
+
 	@Override
 	public <T> T body(Class<T> bodyType) throws IOException, ServletException {
 		return bodyInternal(bodyType, bodyType);

spring-webmvc/src/main/java/org/springframework/web/servlet/function/DefaultServerRequestBuilder.java

@@ -57,6 +57,7 @@ import org.springframework.util.MultiValueMap;
 import org.springframework.validation.BindException;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.HttpMediaTypeNotSupportedException;
+import org.springframework.web.accept.ApiVersionStrategy;
 import org.springframework.web.bind.ServletRequestDataBinder;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.util.UriBuilder;
@@ -74,6 +75,8 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 	private final List<HttpMessageConverter<?>> messageConverters;
 
+	private final @Nullable ApiVersionStrategy versionStrategy;
+
 	private HttpMethod method;
 
 	private URI uri;
@@ -95,6 +98,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 		Assert.notNull(other, "ServerRequest must not be null");
 		this.servletRequest = other.servletRequest();
 		this.messageConverters = new ArrayList<>(other.messageConverters());
+		this.versionStrategy = other.apiVersionStrategy();
 		this.method = other.method();
 		this.uri = other.uri();
 		headers(headers -> headers.addAll(other.headers().asHttpHeaders()));
@@ -203,7 +207,8 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 	@Override
 	public ServerRequest build() {
 		return new BuiltServerRequest(this.servletRequest, this.method, this.uri, this.headers, this.cookies,
-				this.attributes, this.params, this.remoteAddress, this.body, this.messageConverters);
+				this.attributes, this.params, this.remoteAddress, this.body,
+				this.messageConverters, this.versionStrategy);
 	}
 
 
@@ -225,6 +230,8 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 
 		private final List<HttpMessageConverter<?>> messageConverters;
 
+		private final @Nullable ApiVersionStrategy versionStrategy;
+
 		private final MultiValueMap<String, String> params;
 
 		private final @Nullable InetSocketAddress remoteAddress;
@@ -232,7 +239,9 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 		public BuiltServerRequest(HttpServletRequest servletRequest, HttpMethod method, URI uri,
 				HttpHeaders headers, MultiValueMap<String, Cookie> cookies,
 				Map<String, Object> attributes, MultiValueMap<String, String> params,
-				@Nullable InetSocketAddress remoteAddress, byte[] body, List<HttpMessageConverter<?>> messageConverters) {
+				@Nullable InetSocketAddress remoteAddress, byte[] body,
+				List<HttpMessageConverter<?>> messageConverters,
+				@Nullable ApiVersionStrategy versionStrategy) {
 
 			this.servletRequest = servletRequest;
 			this.method = method;
@@ -244,6 +253,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 			this.remoteAddress = remoteAddress;
 			this.body = body;
 			this.messageConverters = messageConverters;
+			this.versionStrategy = versionStrategy;
 		}
 
 		@Override
@@ -289,6 +299,11 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 			return this.messageConverters;
 		}
 
+		@Override
+		public @Nullable ApiVersionStrategy apiVersionStrategy() {
+			return this.versionStrategy;
+		}
+
 		@Override
 		public <T> T body(Class<T> bodyType) throws IOException, ServletException {
 			return bodyInternal(bodyType, bodyType);

spring-webmvc/src/main/java/org/springframework/web/servlet/function/RequestPredicates.java

@@ -54,8 +54,10 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.MultiValueMap;
 import org.springframework.validation.BindException;
+import org.springframework.web.accept.ApiVersionStrategy;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.cors.CorsUtils;
+import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.util.UriBuilder;
 import org.springframework.web.util.UriUtils;
 import org.springframework.web.util.pattern.PathPattern;
@@ -181,6 +183,25 @@ public abstract class RequestPredicates {
 		}
 	}
 
+	/**
+	 * {@code RequestPredicate} to match to the request API version extracted
+	 * from and parsed with the configured {@link ApiVersionStrategy}.
+	 * <p>The version may be one of the following:
+	 * <ul>
+	 * <li>Fixed version ("1.2") -- match this version only.
+	 * <li>Baseline version ("1.2+") -- match this and subsequent versions.
+	 * </ul>
+	 * <p>A baseline version allows n endpoint route to continue to work in
+	 * subsequent versions if it remains compatible until an incompatible change
+	 * eventually leads to the creation of a new route.
+	 * @param version the version to use
+	 * @return the created predicate instance
+	 * @since 7.0
+	 */
+	public static RequestPredicate version(Object version) {
+		return new ApiVersionPredicate(version);
+	}
+
 	/**
 	 * Return a {@code RequestPredicate} that matches if request's HTTP method is {@code GET}
 	 * and the given {@code pattern} matches against the request path.
@@ -388,6 +409,14 @@ public abstract class RequestPredicates {
 		 */
 		void param(String name, String value);
 
+		/**
+		 * Receive notification of an API version predicate. The version could
+		 * be fixed ("1.2") or baseline ("1.2+").
+		 * @param version the configured version
+		 * @since 7.0
+		 */
+		void version(String version);
+
 		/**
 		 * Receive first notification of a logical AND predicate.
 		 * The first subsequent notification will contain the left-hand side of the AND-predicate;
@@ -829,6 +858,69 @@ public abstract class RequestPredicates {
 	}
 
 
+	private static class ApiVersionPredicate implements RequestPredicate {
+
+		private final String version;
+
+		private final boolean baselineVersion;
+
+		private @Nullable Comparable<?> parsedVersion;
+
+		public ApiVersionPredicate(Object version) {
+			if (version instanceof String s) {
+				this.baselineVersion = s.endsWith("+");
+				this.version = initVersion(s, this.baselineVersion);
+			}
+			else {
+				this.baselineVersion = false;
+				this.version = version.toString();
+				this.parsedVersion = (Comparable<?>) version;
+			}
+		}
+
+		private static String initVersion(String version, boolean baselineVersion) {
+			return (baselineVersion ? version.substring(0, version.length() - 1) : version);
+		}
+
+		@Override
+		public boolean test(ServerRequest request) {
+			if (this.parsedVersion == null) {
+				ApiVersionStrategy strategy = request.apiVersionStrategy();
+				Assert.state(strategy != null, "No ApiVersionStrategy to parse version with");
+				this.parsedVersion = strategy.parseVersion(this.version);
+			}
+
+			Comparable<?> requestVersion =
+					(Comparable<?>) request.attribute(HandlerMapping.API_VERSION_ATTRIBUTE).orElse(null);
+
+			if (requestVersion == null) {
+				traceMatch("Version", this.version, null, true);
+				return true;
+			}
+
+			int result = compareVersions(this.parsedVersion, requestVersion);
+			boolean match = (this.baselineVersion ? result <= 0 : result == 0);
+			traceMatch("Version", this.version, requestVersion, match);
+			return match;
+		}
+
+		@SuppressWarnings("unchecked")
+		private <V extends Comparable<V>> int compareVersions(Object v1, Object v2) {
+			return ((V) v1).compareTo((V) v2);
+		}
+
+		@Override
+		public void accept(Visitor visitor) {
+			visitor.version(this.version + (this.baselineVersion ? "+" : ""));
+		}
+
+		@Override
+		public String toString() {
+			return this.version;
+		}
+	}
+
+
 	@Deprecated(since = "7.0", forRemoval = true)
 	private static class PathExtensionPredicate implements RequestPredicate {
 
@@ -1182,6 +1274,11 @@ public abstract class RequestPredicates {
 			return this.delegate.messageConverters();
 		}
 
+		@Override
+		public @Nullable ApiVersionStrategy apiVersionStrategy() {
+			return this.delegate.apiVersionStrategy();
+		}
+
 		@Override
 		public <T> T body(Class<T> bodyType) throws ServletException, IOException {
 			return this.delegate.body(bodyType);

spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerRequest.java

@@ -48,6 +48,7 @@ import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MultiValueMap;
 import org.springframework.validation.BindException;
+import org.springframework.web.accept.ApiVersionStrategy;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.util.ServletRequestPathUtils;
 import org.springframework.web.util.UriBuilder;
@@ -116,6 +117,13 @@ public interface ServerRequest {
 	 */
 	List<HttpMessageConverter<?>> messageConverters();
 
+	/**
+	 * Return the configured {@link ApiVersionStrategy}, or {@code null}.
+	 * @since 7.0
+	 */
+	@Nullable
+	ApiVersionStrategy apiVersionStrategy();
+
 	/**
 	 * Extract the body as an object of the given type.
 	 * @param bodyType the type of return value
@@ -373,6 +381,22 @@ public interface ServerRequest {
 		return new DefaultServerRequest(servletRequest, messageReaders);
 	}
 
+	/**
+	 * Create a new {@code ServerRequest} based on the given {@code HttpServletRequest} and
+	 * message converters.
+	 * @param servletRequest the request
+	 * @param messageReaders the message readers
+	 * @param versionStrategy a strategy to use to parse version
+	 * @return the created {@code ServerRequest}
+	 * @since 7.0
+	 */
+	static ServerRequest create(
+			HttpServletRequest servletRequest, List<HttpMessageConverter<?>> messageReaders,
+			@Nullable ApiVersionStrategy versionStrategy) {
+
+		return new DefaultServerRequest(servletRequest, messageReaders, versionStrategy);
+	}
+
 	/**
 	 * Create a builder with the status, headers, and cookies of the given request.
 	 * @param other the response to copy the status, headers, and cookies from

spring-webmvc/src/main/java/org/springframework/web/servlet/function/ToStringVisitor.java

@@ -118,6 +118,11 @@ class ToStringVisitor implements RouterFunctions.Visitor, RequestPredicates.Visi
 		this.builder.append(String.format("?%s == %s", name, value));
 	}
 
+	@Override
+	public void version(String version) {
+		this.builder.append(String.format("version: %s", version));
+	}
+
 	@Override
 	public void startAnd() {
 		this.builder.append('(');

spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/RouterFunctionMapping.java

@@ -31,6 +31,8 @@ import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter;
 import org.springframework.util.CollectionUtils;
+import org.springframework.web.accept.ApiVersionStrategy;
+import org.springframework.web.accept.DefaultApiVersionStrategy;
 import org.springframework.web.filter.ServerHttpObservationFilter;
 import org.springframework.web.servlet.function.HandlerFunction;
 import org.springframework.web.servlet.function.RouterFunction;
@@ -62,6 +64,8 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 
 	private List<HttpMessageConverter<?>> messageConverters = Collections.emptyList();
 
+	private @Nullable ApiVersionStrategy versionStrategy;
+
 	private boolean detectHandlerFunctionsInAncestorContexts = false;
 
 
@@ -110,6 +114,15 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 		this.messageConverters = messageConverters;
 	}
 
+	/**
+	 * Configure a strategy to manage API versioning.
+	 * @param strategy the strategy to use
+	 * @since 7.0
+	 */
+	public void setApiVersionStrategy(@Nullable ApiVersionStrategy strategy) {
+		this.versionStrategy = strategy;
+	}
+
 	/**
 	 * Set whether to detect handler functions in ancestor ApplicationContexts.
 	 * <p>Default is "false": Only handler functions in the current ApplicationContext
@@ -128,9 +141,11 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 		if (this.routerFunction == null) {
 			initRouterFunctions();
 		}
+
 		if (CollectionUtils.isEmpty(this.messageConverters)) {
 			initMessageConverters();
 		}
+
 		if (this.routerFunction != null) {
 			PathPatternParser patternParser = getPatternParser();
 			if (patternParser == null) {
@@ -138,6 +153,12 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 				setPatternParser(patternParser);
 			}
 			RouterFunctions.changeParser(this.routerFunction, patternParser);
+
+			if (this.versionStrategy instanceof DefaultApiVersionStrategy davs) {
+				if (davs.detectSupportedVersions()) {
+					this.routerFunction.accept(new SupportedVersionVisitor(davs));
+				}
+			}
 		}
 	}
 
@@ -197,15 +218,27 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 
 	@Override
 	protected @Nullable Object getHandlerInternal(HttpServletRequest servletRequest) throws Exception {
-		if (this.routerFunction != null) {
+
-			ServerRequest request = ServerRequest.create(servletRequest, this.messageConverters);
+		if (this.routerFunction == null) {
-			HandlerFunction<?> handlerFunction = this.routerFunction.route(request).orElse(null);
-			setAttributes(servletRequest, request, handlerFunction);
-			return handlerFunction;
-		}
-		else {
 			return null;
 		}
+
+		if (this.versionStrategy != null) {
+			Comparable<?> version = (Comparable<?>) servletRequest.getAttribute(API_VERSION_ATTRIBUTE);
+			if (version == null) {
+				version = this.versionStrategy.resolveParseAndValidateVersion(servletRequest);
+				if (version != null) {
+					servletRequest.setAttribute(API_VERSION_ATTRIBUTE, version);
+				}
+			}
+		}
+
+		ServerRequest request =
+				ServerRequest.create(servletRequest, this.messageConverters, this.versionStrategy);
+
+		HandlerFunction<?> handlerFunction = this.routerFunction.route(request).orElse(null);
+		setAttributes(servletRequest, request, handlerFunction);
+		return handlerFunction;
 	}
 
 	private void setAttributes(HttpServletRequest servletRequest, ServerRequest request,

spring-webmvc/src/main/java/org/springframework/web/servlet/function/support/SupportedVersionVisitor.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2002-present 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.servlet.function.support;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Function;
+
+import org.springframework.core.io.Resource;
+import org.springframework.http.HttpMethod;
+import org.springframework.web.accept.DefaultApiVersionStrategy;
+import org.springframework.web.servlet.function.HandlerFunction;
+import org.springframework.web.servlet.function.RequestPredicate;
+import org.springframework.web.servlet.function.RequestPredicates;
+import org.springframework.web.servlet.function.RouterFunction;
+import org.springframework.web.servlet.function.RouterFunctions;
+import org.springframework.web.servlet.function.ServerRequest;
+
+/**
+ * {@link RequestPredicates.Visitor} that discovers versions used in routes in
+ * order to add them to the list of supported versions.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ */
+final class SupportedVersionVisitor implements RouterFunctions.Visitor, RequestPredicates.Visitor {
+
+	private final DefaultApiVersionStrategy versionStrategy;
+
+
+	SupportedVersionVisitor(DefaultApiVersionStrategy versionStrategy) {
+		this.versionStrategy = versionStrategy;
+	}
+
+
+	// RouterFunctions.Visitor
+
+	@Override
+	public void startNested(RequestPredicate predicate) {
+		predicate.accept(this);
+	}
+
+	@Override
+	public void endNested(RequestPredicate predicate) {
+	}
+
+	@Override
+	public void route(RequestPredicate predicate, HandlerFunction<?> handlerFunction) {
+		predicate.accept(this);
+	}
+
+	@Override
+	public void resources(Function<ServerRequest, Optional<Resource>> lookupFunction) {
+	}
+
+	@Override
+	public void attributes(Map<String, Object> attributes) {
+	}
+
+	@Override
+	public void unknown(RouterFunction<?> routerFunction) {
+	}
+
+
+	// RequestPredicates.Visitor
+
+	@Override
+	public void method(Set<HttpMethod> methods) {
+	}
+
+	@Override
+	public void path(String pattern) {
+	}
+
+	@SuppressWarnings("removal")
+	@Override
+	public void pathExtension(String extension) {
+	}
+
+	@Override
+	public void header(String name, String value) {
+	}
+
+	@Override
+	public void param(String name, String value) {
+
+	}
+
+	@Override
+	public void version(String version) {
+		this.versionStrategy.addMappedVersion(
+				(version.endsWith("+") ? version.substring(0, version.length() - 1) : version));
+	}
+
+	@Override
+	public void startAnd() {
+	}
+
+	@Override
+	public void and() {
+	}
+
+	@Override
+	public void endAnd() {
+	}
+
+	@Override
+	public void startOr() {
+	}
+
+	@Override
+	public void or() {
+	}
+
+	@Override
+	public void endOr() {
+	}
+
+	@Override
+	public void startNegate() {
+	}
+
+	@Override
+	public void endNegate() {
+	}
+
+	@Override
+	public void unknown(RequestPredicate predicate) {
+	}
+
+}

spring-webmvc/src/test/java/org/springframework/web/servlet/function/RequestPredicatesTests.java

@@ -27,11 +27,15 @@ import org.junit.jupiter.api.Test;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
+import org.springframework.web.accept.ApiVersionStrategy;
+import org.springframework.web.accept.DefaultApiVersionStrategy;
+import org.springframework.web.accept.SemanticApiVersionParser;
 import org.springframework.web.servlet.handler.PathPatternsTestUtils;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.util.pattern.PathPatternParser;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.web.servlet.HandlerMapping.API_VERSION_ATTRIBUTE;
 
 /**
  * @author Arjen Poutsma
@@ -266,12 +270,30 @@ class RequestPredicatesTests {
 		assertThat(predicate.test(request)).isFalse();
 	}
 
+	@Test
+	void version() {
+		assertThat(RequestPredicates.version("1.1").test(serverRequest("1.1"))).isTrue();
+		assertThat(RequestPredicates.version("1.1+").test(serverRequest("1.5"))).isTrue();
+		assertThat(RequestPredicates.version("1.1").test(serverRequest("1.5"))).isFalse();
+	}
 
-	private ServerRequest initRequest(String httpMethod, String requestUri) {
+	private static ServerRequest serverRequest(String version) {
+
+		ApiVersionStrategy strategy = new DefaultApiVersionStrategy(
+				List.of(exchange -> null), new SemanticApiVersionParser(), true, null, false, null);
+
+		MockHttpServletRequest servletRequest =
+				PathPatternsTestUtils.initRequest("GET", null, "/path", true,
+						req -> req.setAttribute(API_VERSION_ATTRIBUTE, strategy.parseVersion(version)));
+
+		return new DefaultServerRequest(servletRequest, Collections.emptyList(), strategy);
+	}
+
+	private static ServerRequest initRequest(String httpMethod, String requestUri) {
 		return initRequest(httpMethod, requestUri, null);
 	}
 
-	private ServerRequest initRequest(
+	private static ServerRequest initRequest(
 			String httpMethod, String requestUri, @Nullable Consumer<MockHttpServletRequest> initializer) {
 
 		return new DefaultServerRequest(

spring-webmvc/src/test/java/org/springframework/web/servlet/function/support/RouterFunctionMappingVersionTests.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2002-present 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.servlet.function.support;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.servlet.config.annotation.ApiVersionConfigurer;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import org.springframework.web.servlet.function.HandlerFunction;
+import org.springframework.web.servlet.function.RouterFunction;
+import org.springframework.web.servlet.function.RouterFunctions;
+import org.springframework.web.servlet.function.ServerRequest;
+import org.springframework.web.servlet.function.ServerResponse;
+import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
+import org.springframework.web.testfixture.servlet.MockServletContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.web.servlet.function.RequestPredicates.version;
+
+/**
+ * {@link RouterFunctionMapping} integration tests for API versioning.
+ * @author Rossen Stoyanchev
+ */
+public class RouterFunctionMappingVersionTests {
+
+	private final MockServletContext servletContext = new MockServletContext();
+
+	private RouterFunctionMapping mapping;
+
+
+	@BeforeEach
+	void setUp() {
+		AnnotationConfigWebApplicationContext wac = new AnnotationConfigWebApplicationContext();
+		wac.setServletContext(this.servletContext);
+		wac.register(WebConfig.class);
+		wac.refresh();
+
+		this.mapping = wac.getBean(RouterFunctionMapping.class);
+	}
+
+
+	@Test
+	void mapVersion() throws Exception {
+		testGetHandler("1.0", "none");
+		testGetHandler("1.1", "none");
+		testGetHandler("1.2", "1.2");
+		testGetHandler("1.3", "1.2");
+		testGetHandler("1.5", "1.5");
+	}
+
+
+	private void testGetHandler(String version, String expectedBody) throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/");
+		request.addHeader("X-API-Version", version);
+		HandlerFunction<?> handler = (HandlerFunction<?>) this.mapping.getHandler(request).getHandler();
+		assertThat(((TestHandler) handler).body()).isEqualTo(expectedBody);
+	}
+
+
+	@EnableWebMvc
+	private static class WebConfig implements WebMvcConfigurer {
+
+		@Override
+		public void configureApiVersioning(ApiVersionConfigurer configurer) {
+			configurer.useRequestHeader("X-API-Version").addSupportedVersions("1", "1.1", "1.3");
+		}
+
+		@Bean
+		RouterFunction<?> routerFunction() {
+			return RouterFunctions.route()
+					.path("/", builder -> builder
+							.GET(version("1.5"), new TestHandler("1.5"))
+							.GET(version("1.2+"), new TestHandler("1.2"))
+							.GET(new TestHandler("none")))
+					.build();
+		}
+	}
+
+
+	private record TestHandler(String body) implements HandlerFunction<ServerResponse> {
+
+		@Override
+		public ServerResponse handle(ServerRequest request) {
+			return ServerResponse.ok().body(body);
+		}
+	}
+
+}