WebMvc respects RouterFunction beans ordering

Closes gh-28595

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -119,12 +119,11 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 	}
 
 	private List<RouterFunction<?>> routerFunctions() {
-		List<RouterFunction<?>> functions = obtainApplicationContext()
+		return obtainApplicationContext()
 				.getBeanProvider(RouterFunction.class)
 				.orderedStream()
-				.map(router -> (RouterFunction<?>)router)
+				.map(router -> (RouterFunction<?>) router)
 				.collect(Collectors.toList());
-		return (!CollectionUtils.isEmpty(functions) ? functions : Collections.emptyList());
 	}
 
 	private void logRouterFunctions(List<RouterFunction<?>> routerFunctions) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -20,6 +20,7 @@ import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
 
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.function.server.HandlerFunction;
@@ -72,6 +73,23 @@ public class RouterFunctionMappingTests {
 				.verify();
 	}
 
+	@Test
+	void empty() throws Exception {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.refresh();
+
+		RouterFunctionMapping mapping = new RouterFunctionMapping();
+		mapping.setMessageReaders(this.codecConfigurer.getReaders());
+		mapping.setApplicationContext(context);
+		mapping.afterPropertiesSet();
+
+		Mono<Object> result = mapping.getHandler(createExchange("https://example.com/match"));
+
+		StepVerifier.create(result)
+				.expectComplete()
+				.verify();
+	}
+
 	@Test
 	void changeParser() throws Exception {
 		HandlerFunction<ServerResponse> handlerFunction = request -> ServerResponse.ok().build();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -19,11 +19,10 @@ package org.springframework.web.servlet.function.support;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
+import java.util.stream.Collectors;
 
 import javax.servlet.http.HttpServletRequest;
 
-import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.SpringProperties;
@@ -135,7 +134,7 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		if (this.routerFunction == null) {
-			initRouterFunction();
+			initRouterFunctions();
 		}
 		if (CollectionUtils.isEmpty(this.messageConverters)) {
 			initMessageConverters();
@@ -154,20 +153,39 @@ public class RouterFunctionMapping extends AbstractHandlerMapping implements Ini
 	 * Detect a all {@linkplain RouterFunction router functions} in the
 	 * current application context.
 	 */
-	@SuppressWarnings({"rawtypes", "unchecked"})
-	private void initRouterFunction() {
-		ApplicationContext applicationContext = obtainApplicationContext();
-		Map<String, RouterFunction> beans =
-				(this.detectHandlerFunctionsInAncestorContexts ?
-						BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RouterFunction.class) :
-						applicationContext.getBeansOfType(RouterFunction.class));
-		List<RouterFunction> routerFunctions = new ArrayList<>(beans.values());
+	private void initRouterFunctions() {
+		List<RouterFunction<?>> routerFunctions = routerFunctions();
 		this.routerFunction = routerFunctions.stream().reduce(RouterFunction::andOther).orElse(null);
 		logRouterFunctions(routerFunctions);
 	}
 
-	@SuppressWarnings("rawtypes")
-	private void logRouterFunctions(List<RouterFunction> routerFunctions) {
+	private List<RouterFunction<?>> routerFunctions() {
+		List<RouterFunction<?>> routerFunctions = new ArrayList<>();
+		if (this.detectHandlerFunctionsInAncestorContexts) {
+			detectRouterFunctionsInAncestorContexts(obtainApplicationContext(), routerFunctions);
+		}
+		obtainApplicationContext()
+				.getBeanProvider(RouterFunction.class)
+				.orderedStream()
+				.map(router -> (RouterFunction<?>) router)
+				.collect(Collectors.toCollection(() -> routerFunctions));
+		return routerFunctions;
+	}
+
+	private void detectRouterFunctionsInAncestorContexts(
+			ApplicationContext applicationContext, List<RouterFunction<?>> routerFunctions) {
+
+		ApplicationContext parentContext = applicationContext.getParent();
+		if (parentContext != null) {
+			detectRouterFunctionsInAncestorContexts(parentContext, routerFunctions);
+			parentContext.getBeanProvider(RouterFunction.class)
+					.orderedStream()
+					.map(router -> (RouterFunction<?>) router)
+					.collect(Collectors.toCollection(() -> routerFunctions));
+		}
+	}
+
+	private void logRouterFunctions(List<RouterFunction<?>> routerFunctions) {
 		if (mappingsLogger.isDebugEnabled()) {
 			routerFunctions.forEach(function -> mappingsLogger.debug("Mapped " + function));
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -21,7 +21,10 @@ import java.util.List;
 import java.util.Optional;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.web.servlet.HandlerExecutionChain;
 import org.springframework.web.servlet.HandlerMapping;
@@ -41,7 +44,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class RouterFunctionMappingTests {
 
-	private List<HttpMessageConverter<?>> messageConverters = Collections.emptyList();
+	private final List<HttpMessageConverter<?>> messageConverters = Collections.emptyList();
 
 	@Test
 	void normal() throws Exception {
@@ -71,6 +74,65 @@ class RouterFunctionMappingTests {
 		assertThat(result).isNull();
 	}
 
+	@Test
+	void empty() throws Exception {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.refresh();
+
+		RouterFunctionMapping mapping = new RouterFunctionMapping();
+		mapping.setMessageConverters(this.messageConverters);
+		mapping.setApplicationContext(context);
+		mapping.afterPropertiesSet();
+
+		MockHttpServletRequest request = createTestRequest("/match");
+		HandlerExecutionChain result = mapping.getHandler(request);
+
+		assertThat(result).isNull();
+	}
+
+	@ParameterizedTest
+	@ValueSource(booleans = {true, false})
+	void detectHandlerFunctionsInAncestorContexts(boolean detect) throws Exception {
+		HandlerFunction<ServerResponse> function1 = request -> ServerResponse.ok().build();
+		HandlerFunction<ServerResponse> function2 = request -> ServerResponse.ok().build();
+		HandlerFunction<ServerResponse> function3 = request -> ServerResponse.ok().build();
+
+		AnnotationConfigApplicationContext context1 = new AnnotationConfigApplicationContext();
+		context1.registerBean(RouterFunction.class, () -> RouterFunctions.route().GET("/fn1", function1).build());
+		context1.refresh();
+
+		AnnotationConfigApplicationContext context2 = new AnnotationConfigApplicationContext();
+		context2.registerBean(RouterFunction.class, () -> RouterFunctions.route().GET("/fn2", function2).build());
+		context2.setParent(context1);
+		context2.refresh();
+
+		AnnotationConfigApplicationContext context3 = new AnnotationConfigApplicationContext();
+		context3.registerBean(RouterFunction.class, () -> RouterFunctions.route().GET("/fn3", function3).build());
+		context3.setParent(context2);
+		context3.refresh();
+
+		RouterFunctionMapping mapping = new RouterFunctionMapping();
+		mapping.setDetectHandlerFunctionsInAncestorContexts(detect);
+		mapping.setMessageConverters(this.messageConverters);
+		mapping.setApplicationContext(context3);
+		mapping.afterPropertiesSet();
+
+		HandlerExecutionChain chain1 = mapping.getHandler(createTestRequest("/fn1"));
+		HandlerExecutionChain chain2 = mapping.getHandler(createTestRequest("/fn2"));
+		if (detect) {
+			assertThat(chain1).isNotNull().extracting(HandlerExecutionChain::getHandler).isSameAs(function1);
+			assertThat(chain2).isNotNull().extracting(HandlerExecutionChain::getHandler).isSameAs(function2);
+		}
+		else {
+			assertThat(chain1).isNull();
+			assertThat(chain2).isNull();
+		}
+
+		HandlerExecutionChain chain3 = mapping.getHandler(createTestRequest("/fn3"));
+		assertThat(chain3).isNotNull().extracting(HandlerExecutionChain::getHandler).isSameAs(function3);
+
+	}
+
 	@Test
 	void changeParser() throws Exception {
 		HandlerFunction<ServerResponse> handlerFunction = request -> ServerResponse.ok().build();