Fix regression in WebFlux support for WebDAV methods

This commit ensures that WebFlux's RequestMethodsRequestCondition
supports HTTP methods that are not in the RequestMethod enum.

- RequestMethod::resolve is introduced, to convert from a HttpMethod
(name) to enum values.
- RequestMethod::asHttpMethod is introduced, to convert from enum value
to HttpMethod.
- HttpMethod::valueOf replaced Map-based lookup to a switch statement
- Enabled tests that check for WebDAV methods

See gh-27697
Closes gh-29981

spring-web/src/main/java/org/springframework/http/HttpMethod.java

@@ -17,10 +17,6 @@
 package org.springframework.http;
 
 import java.io.Serializable;
-import java.util.Arrays;
-import java.util.Map;
-import java.util.function.Function;
-import java.util.stream.Collectors;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -88,9 +84,6 @@ public final class HttpMethod implements Comparable<HttpMethod>, Serializable {
 
 	private static final HttpMethod[] values = new HttpMethod[] { GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE };
 
-	private static final Map<String, HttpMethod> mappings = Arrays.stream(values)
-			.collect(Collectors.toUnmodifiableMap(HttpMethod::name, Function.identity()));
-
 
 	private final String name;
 
@@ -121,13 +114,17 @@ public static HttpMethod[] values() {
 	 */
 	public static HttpMethod valueOf(String method) {
 		Assert.notNull(method, "Method must not be null");
-		HttpMethod result = mappings.get(method);
-		if (result != null) {
-			return result;
-		}
-		else {
-			return new HttpMethod(method);
-		}
+		return switch (method) {
+			case "GET" -> GET;
+			case "HEAD" -> HEAD;
+			case "POST" -> POST;
+			case "PUT" -> PUT;
+			case "PATCH" -> PATCH;
+			case "DELETE" -> DELETE;
+			case "OPTIONS" -> OPTIONS;
+			case "TRACE" -> TRACE;
+			default -> new HttpMethod(method);
+		};
 	}
 
 	/**

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestMethod.java

@@ -16,6 +16,10 @@
 
 package org.springframework.web.bind.annotation;
 
+import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
 /**
  * Enumeration of HTTP request methods. Intended for use with the
  * {@link RequestMapping#method()} attribute of the {@link RequestMapping} annotation.
@@ -34,6 +38,62 @@
  */
 public enum RequestMethod {
 
-	GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE
+	GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE;
+
+
+	/**
+	 * Resolve the given method value to an {@code RequestMethod} enum value.
+	 * Returns {@code null} if {@code method} has no corresponding value.
+	 * @param method the method value as a String
+	 * @return the corresponding {@code RequestMethod}, or {@code null} if not found
+	 * @since 6.0.6
+	 */
+	@Nullable
+	public static RequestMethod resolve(String method) {
+		Assert.notNull(method, "Method must not be null");
+		return switch (method) {
+			case "GET" -> GET;
+			case "HEAD" -> HEAD;
+			case "POST" -> POST;
+			case "PUT" -> PUT;
+			case "PATCH" -> PATCH;
+			case "DELETE" -> DELETE;
+			case "OPTIONS" -> OPTIONS;
+			case "TRACE" -> TRACE;
+			default -> null;
+		};
+	}
+
+	/**
+	 * Resolve the given {@link HttpMethod} to a {@code RequestMethod} enum value.
+	 * Returns {@code null} if {@code httpMethod} has no corresponding value.
+	 * @param httpMethod the http method object
+	 * @return the corresponding {@code RequestMethod}, or {@code null} if not found
+	 * @since 6.0.6
+	 */
+	@Nullable
+	public static RequestMethod resolve(HttpMethod httpMethod) {
+		Assert.notNull(httpMethod, "HttpMethod must not be null");
+		return resolve(httpMethod.name());
+	}
+
+
+	/**
+	 * Return the {@link HttpMethod} corresponding to this {@code RequestMethod}.
+	 * @return the http method for this request method
+	 * @since 6.0.6
+	 */
+	public HttpMethod asHttpMethod() {
+		return switch (this) {
+			case GET -> HttpMethod.GET;
+			case HEAD -> HttpMethod.HEAD;
+			case POST -> HttpMethod.POST;
+			case PUT -> HttpMethod.PUT;
+			case PATCH -> HttpMethod.PATCH;
+			case DELETE -> HttpMethod.DELETE;
+			case OPTIONS -> HttpMethod.OPTIONS;
+			case TRACE -> HttpMethod.TRACE;
+		};
+	}
 
 }

spring-web/src/test/java/org/springframework/web/bind/annotation/RequestMethodTests.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2002-2023 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.web.bind.annotation;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.HttpMethod;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Arjen Poutsma
+ */
+class RequestMethodTests {
+
+	@Test
+	void resolveString() {
+		String[] methods = new String[]{"GET", "HEAD", "POST", "PUT", "PATCH", "DELETE", "OPTIONS", "TRACE"};
+		for (String httpMethod : methods) {
+			RequestMethod requestMethod = RequestMethod.resolve(httpMethod);
+			assertThat(requestMethod).isNotNull();
+			assertThat(requestMethod.name()).isEqualTo(httpMethod);
+		}
+		assertThat(RequestMethod.resolve("PROPFIND")).isNull();
+	}
+
+	@Test
+	void resolveHttpMethod() {
+		for (HttpMethod httpMethod : HttpMethod.values()) {
+			RequestMethod requestMethod = RequestMethod.resolve(httpMethod);
+			assertThat(requestMethod).isNotNull();
+			assertThat(requestMethod.name()).isEqualTo(httpMethod.name());
+		}
+		assertThat(RequestMethod.resolve(HttpMethod.valueOf("PROPFIND"))).isNull();
+	}
+
+	@Test
+	void asHttpMethod() {
+		for (RequestMethod requestMethod : RequestMethod.values()) {
+			HttpMethod httpMethod = requestMethod.asHttpMethod();
+			assertThat(httpMethod).isNotNull();
+			assertThat(httpMethod.name()).isEqualTo(requestMethod.name());
+		}
+	}
+}

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/RequestMethodsRequestCondition.java

@@ -46,9 +46,9 @@ public final class RequestMethodsRequestCondition extends AbstractRequestConditi
 
 	static {
 		requestMethodConditionCache = CollectionUtils.newHashMap(RequestMethod.values().length);
-		for (RequestMethod method : RequestMethod.values()) {
-			requestMethodConditionCache.put(
-					HttpMethod.valueOf(method.name()), new RequestMethodsRequestCondition(method));
+		for (RequestMethod requestMethod : RequestMethod.values()) {
+			requestMethodConditionCache.put(requestMethod.asHttpMethod(),
+					new RequestMethodsRequestCondition(requestMethod));
 		}
 	}
 
@@ -150,16 +150,15 @@ private RequestMethodsRequestCondition matchPreFlight(ServerHttpRequest request)
 	}
 
 	@Nullable
-	private RequestMethodsRequestCondition matchRequestMethod(@Nullable HttpMethod httpMethod) {
-		if (httpMethod == null) {
-			return null;
-		}
-		RequestMethod requestMethod = RequestMethod.valueOf(httpMethod.name());
-		if (getMethods().contains(requestMethod)) {
-			return requestMethodConditionCache.get(httpMethod);
-		}
-		if (requestMethod.equals(RequestMethod.HEAD) && getMethods().contains(RequestMethod.GET)) {
-			return requestMethodConditionCache.get(HttpMethod.GET);
+	private RequestMethodsRequestCondition matchRequestMethod(HttpMethod httpMethod) {
+		RequestMethod requestMethod = RequestMethod.resolve(httpMethod);
+		if (requestMethod != null) {
+			if (getMethods().contains(requestMethod)) {
+				return requestMethodConditionCache.get(httpMethod);
+			}
+			if (requestMethod.equals(RequestMethod.HEAD) && getMethods().contains(RequestMethod.GET)) {
+				return requestMethodConditionCache.get(HttpMethod.GET);
+			}
 		}
 		return null;
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/condition/RequestMethodsRequestConditionTests.java

@@ -19,7 +19,6 @@
 import java.net.URISyntaxException;
 import java.util.Collections;
 
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.http.HttpHeaders;
@@ -44,8 +43,6 @@
  */
 public class RequestMethodsRequestConditionTests {
 
-	// TODO: custom method, CORS pre-flight (see @Disabled)
-
 	@Test
 	public void getMatchingCondition() throws Exception {
 		testMatch(new RequestMethodsRequestCondition(GET), GET);
@@ -73,19 +70,19 @@ public void getMatchingConditionWithEmptyConditions() throws Exception {
 	}
 
 	@Test
-	@Disabled
 	public void getMatchingConditionWithCustomMethod() throws Exception {
 		ServerWebExchange exchange = getExchange("PROPFIND");
 		assertThat(new RequestMethodsRequestCondition().getMatchingCondition(exchange)).isNotNull();
 		assertThat(new RequestMethodsRequestCondition(GET, POST).getMatchingCondition(exchange)).isNull();
 	}
 
 	@Test
-	@Disabled
-	public void getMatchingConditionWithCorsPreFlight() throws Exception {
-		ServerWebExchange exchange = getExchange("OPTIONS");
-		exchange.getRequest().getHeaders().add("Origin", "https://example.com");
-		exchange.getRequest().getHeaders().add(HttpHeaders.ACCESS_CONTROL_REQUEST_METHOD, "PUT");
+	public void getMatchingConditionWithCorsPreFlight() {
+		MockServerHttpRequest request = MockServerHttpRequest.method(HttpMethod.valueOf("OPTIONS"), "/")
+				.header("Origin", "https://example.com")
+				.header(HttpHeaders.ACCESS_CONTROL_REQUEST_METHOD, "PUT")
+				.build();
+		ServerWebExchange exchange = MockServerWebExchange.from(request);
 
 		assertThat(new RequestMethodsRequestCondition().getMatchingCondition(exchange)).isNotNull();
 		assertThat(new RequestMethodsRequestCondition(PUT).getMatchingCondition(exchange)).isNotNull();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/RequestMethodsRequestCondition.java

@@ -157,19 +157,15 @@ private RequestMethodsRequestCondition matchPreFlight(HttpServletRequest request
 
 	@Nullable
 	private RequestMethodsRequestCondition matchRequestMethod(String httpMethodValue) {
-		RequestMethod requestMethod;
-		try {
-			requestMethod = RequestMethod.valueOf(httpMethodValue);
+		RequestMethod requestMethod = RequestMethod.resolve(httpMethodValue);
+		if (requestMethod != null) {
 			if (getMethods().contains(requestMethod)) {
 				return requestMethodConditionCache.get(httpMethodValue);
 			}
 			if (requestMethod.equals(RequestMethod.HEAD) && getMethods().contains(RequestMethod.GET)) {
 				return requestMethodConditionCache.get(HttpMethod.GET.name());
 			}
 		}
-		catch (IllegalArgumentException ex) {
-			// Custom request method
-		}
 		return null;
 	}