Support for MediaType mappings in ResourceWebHandler

Closes gh-26170

spring-webflux/src/test/java/org/springframework/web/reactive/config/ResourceHandlerRegistryTests.java

@@ -17,6 +17,7 @@
 package org.springframework.web.reactive.config;
 
 import java.time.Duration;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
@@ -28,6 +29,7 @@ import reactor.test.StepVerifier;
 import org.springframework.cache.concurrent.ConcurrentMapCache;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.http.CacheControl;
+import org.springframework.http.MediaType;
 import org.springframework.http.server.PathContainer;
 import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.handler.SimpleUrlHandlerMapping;
@@ -99,6 +101,16 @@ public class ResourceHandlerRegistryTests {
 				.isEqualTo(CacheControl.noCache().cachePrivate().getHeaderValue());
 	}
 
+	@Test
+	public void mediaTypes() {
+		MediaType mediaType = MediaType.parseMediaType("foo/bar");
+		this.registration.setMediaTypes(Collections.singletonMap("bar", mediaType));
+		ResourceWebHandler requestHandler = this.registration.getRequestHandler();
+
+		assertThat(requestHandler.getMediaTypes()).size().isEqualTo(1);
+		assertThat(requestHandler.getMediaTypes()).containsEntry("bar", mediaType);
+	}
+
 	@Test
 	public void order() {
 		assertThat(this.registry.getHandlerMapping().getOrder()).isEqualTo(Integer.MAX_VALUE -1);

spring-webflux/src/test/java/org/springframework/web/reactive/resource/ResourceWebHandlerTests.java

@@ -214,6 +214,24 @@ public class ResourceWebHandlerTests {
 		assertResponseBody(exchange, "function foo() { console.log(\"hello world\"); }");
 	}
 
+	@Test
+	public void getResourceWithRegisteredMediaType() throws Exception {
+		MediaType mediaType = new MediaType("foo", "bar");
+
+		ResourceWebHandler handler = new ResourceWebHandler();
+		handler.setLocations(Collections.singletonList(new ClassPathResource("test/", getClass())));
+		handler.setMediaTypes(Collections.singletonMap("bar", mediaType));
+		handler.afterPropertiesSet();
+
+		MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get(""));
+		setPathWithinHandlerMapping(exchange, "foo.bar");
+		handler.handle(exchange).block(TIMEOUT);
+
+		HttpHeaders headers = exchange.getResponse().getHeaders();
+		assertThat(headers.getContentType()).isEqualTo(mediaType);
+		assertResponseBody(exchange, "foo bar foo bar foo bar");
+	}
+
 	@Test // SPR-14577
 	public void getMediaTypeWithFavorPathExtensionOff() throws Exception {
 		List<Resource> paths = Collections.singletonList(new ClassPathResource("test/", getClass()));

spring-webflux/src/test/resources/org/springframework/web/reactive/resource/test/foo.bar

@@ -0,0 +1 @@
+foo bar foo bar foo bar