Adds GatewayRouterFunctions.route()

This overloads the methods from RouterFunctions and automatically adds the FilterFunctions.routeId() filter, which adds the routeId as a request attribute.

This request attribute is in turn, used to determine if the current route is a "gateway route";

See gh-2949

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/FilterFunctions.java

@@ -145,6 +145,13 @@ public interface FilterFunctions {
 		};
 	}
 
+	static HandlerFilterFunction<ServerResponse, ServerResponse> routeId(String routeId) {
+		return (request, next) -> {
+			request.attributes().put(MvcUtils.GATEWAY_ROUTE_ID_ATTR, routeId);
+			return next.handle(request);
+		};
+	}
+
 	@Shortcut
 	static HandlerFilterFunction<ServerResponse, ServerResponse> setPath(String path) {
 		UriTemplate uriTemplate = new UriTemplate(path);

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/GatewayRouterFunctions.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2013-2023 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.cloud.gateway.server.mvc.handler;
+
+import org.springframework.web.servlet.function.HandlerFunction;
+import org.springframework.web.servlet.function.RequestPredicate;
+import org.springframework.web.servlet.function.RouterFunction;
+import org.springframework.web.servlet.function.RouterFunctions;
+import org.springframework.web.servlet.function.RouterFunctions.Builder;
+import org.springframework.web.servlet.function.ServerResponse;
+
+import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.routeId;
+
+public abstract class GatewayRouterFunctions {
+
+	private GatewayRouterFunctions() {
+	}
+
+	public static Builder route() {
+		return RouterFunctions.route();
+	}
+
+	public static Builder route(String routeId) {
+		return RouterFunctions.route().filter(routeId(routeId));
+	}
+
+	public static <T extends ServerResponse> RouterFunction<T> route(RequestPredicate predicate,
+			HandlerFunction<T> handlerFunction) {
+		return RouterFunctions.route(predicate, handlerFunction);
+	}
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerFunctions.java

@@ -29,7 +29,7 @@ import org.springframework.web.servlet.function.ServerResponse;
 
 public abstract class HandlerFunctions {
 
-	protected HandlerFunctions() {
+	private HandlerFunctions() {
 
 	}
 

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/ServerMvcIntegrationTests.java

@@ -78,11 +78,13 @@ import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunction
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.redirectTo;
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.removeRequestHeader;
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.rewritePath;
+import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.routeId;
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.setPath;
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.setStatus;
 import static org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.stripPrefix;
 import static org.springframework.cloud.gateway.server.mvc.filter.LoadBalancerFilterFunctions.lb;
 import static org.springframework.cloud.gateway.server.mvc.filter.RetryFilterFunctions.retry;
+import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
 import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;
 import static org.springframework.cloud.gateway.server.mvc.predicate.GatewayRequestPredicates.cookie;
 import static org.springframework.cloud.gateway.server.mvc.predicate.GatewayRequestPredicates.header;
@@ -93,7 +95,6 @@ import static org.springframework.http.MediaType.MULTIPART_FORM_DATA;
 import static org.springframework.web.servlet.function.RequestPredicates.GET;
 import static org.springframework.web.servlet.function.RequestPredicates.POST;
 import static org.springframework.web.servlet.function.RequestPredicates.path;
-import static org.springframework.web.servlet.function.RouterFunctions.route;
 
 @SuppressWarnings("unchecked")
 @SpringBootTest(properties = {}, webEnvironment = WebEnvironment.RANDOM_PORT)
@@ -406,15 +407,16 @@ public class ServerMvcIntegrationTests {
 		@Bean
 		public RouterFunction<ServerResponse> gatewayRouterFunctionsSetStatusAndAddRespHeader() {
 			// @formatter:off
-			return (RouterFunction<ServerResponse>) route().GET("/status/{status}", http())
+			return (RouterFunction<ServerResponse>) route("testsetstatus")
+					.GET("/status/{status}", http())
 					.filter(new HttpbinUriResolver())
 					.filter(setStatus(HttpStatus.TOO_MANY_REQUESTS))
 					.filter(addResponseHeader("X-Status", "{status}"))
-					.withAttribute(MvcUtils.GATEWAY_ROUTE_ID_ATTR, "testsetstatus")
-				.build().andOther(route().GET("/anything/addresheader", http())
+				.build().andOther(route()
+					.GET("/anything/addresheader", http())
+					.filter(routeId("testaddresponseheader"))
 					.filter(new HttpbinUriResolver())
 					.filter(addResponseHeader("X-Bar", "val1"))
-					.withAttribute(MvcUtils.GATEWAY_ROUTE_ID_ATTR, "testaddresponseheader")
 				.build());
 			// @formatter:on
 		}
@@ -581,13 +583,11 @@ public class ServerMvcIntegrationTests {
 		@Bean
 		public RouterFunction<ServerResponse> gatewayRouterFunctionsForm() {
 			// @formatter:off
-
-			return route()
+			return route("testform")
 					.POST("/post", header("test", "form"), http())
 					.filter(new LocalServerPortUriResolver())
 					.filter(prefixPath("/test"))
 					.filter(addRequestHeader("X-Test", "form"))
-					.withAttribute(MvcUtils.GATEWAY_ROUTE_ID_ATTR, "testform")
 					.build();
 			// @formatter:on
 		}