Polishing

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

@@ -85,8 +85,8 @@ public class MappingMediaTypeFileExtensionResolver implements MediaTypeFileExten
 	}
 
 	private void addFileExtension(MediaType mediaType, String extension) {
-		List<String> list = this.fileExtensions.computeIfAbsent(mediaType, key -> new CopyOnWriteArrayList<>());
-		list.add(extension);
+		this.fileExtensions.computeIfAbsent(mediaType, key -> new CopyOnWriteArrayList<>())
+				.add(extension);
 	}
 
 
@@ -103,7 +103,7 @@ public class MappingMediaTypeFileExtensionResolver implements MediaTypeFileExten
 
 	/**
 	 * Use this method for a reverse lookup from extension to MediaType.
-	 * @return a MediaType for the key, or {@code null} if none found
+	 * @return a MediaType for the extension, or {@code null} if none found
 	 */
 	@Nullable
 	protected MediaType lookupMediaType(String extension) {

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

 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -21,8 +21,8 @@ import java.util.List;
 import org.springframework.http.MediaType;
 
 /**
- * Strategy to resolve {@link MediaType} to a list of file extensions.
- * For example resolve "application/json" to "json".
+ * Strategy to resolve a {@link MediaType} to a list of file extensions —
+ * for example, to resolve "application/json" to "json".
  *
  * @author Rossen Stoyanchev
  * @since 3.2
@@ -30,14 +30,14 @@ import org.springframework.http.MediaType;
 public interface MediaTypeFileExtensionResolver {
 
 	/**
-	 * Resolve the given media type to a list of path extensions.
+	 * Resolve the given media type to a list of file extensions.
 	 * @param mediaType the media type to resolve
 	 * @return a list of extensions or an empty list (never {@code null})
 	 */
 	List<String> resolveFileExtensions(MediaType mediaType);
 
 	/**
-	 * Return all registered file extensions.
+	 * Get all registered file extensions.
 	 * @return a list of extensions or an empty list (never {@code null})
 	 */
 	List<String> getAllFileExtensions();

spring-web/src/test/java/org/springframework/web/accept/MappingMediaTypeFileExtensionResolverTests.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.accept;
 
 import java.util.Collections;
@@ -33,23 +34,22 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 public class MappingMediaTypeFileExtensionResolverTests {
 
+	private final Map<String, MediaType> mapping = Collections.singletonMap("json", MediaType.APPLICATION_JSON);
+	private final MappingMediaTypeFileExtensionResolver resolver = new MappingMediaTypeFileExtensionResolver(this.mapping);
+
 	@Test
 	public void resolveExtensions() {
-		Map<String, MediaType> mapping = Collections.singletonMap("json", MediaType.APPLICATION_JSON);
-		MappingMediaTypeFileExtensionResolver resolver = new MappingMediaTypeFileExtensionResolver(mapping);
-		List<String> extensions = resolver.resolveFileExtensions(MediaType.APPLICATION_JSON);
+		List<String> extensions = this.resolver.resolveFileExtensions(MediaType.APPLICATION_JSON);
 
-		assertThat(extensions.size()).isEqualTo(1);
+		assertThat(extensions).size().isEqualTo(1);
 		assertThat(extensions.get(0)).isEqualTo("json");
 	}
 
 	@Test
 	public void resolveExtensionsNoMatch() {
-		Map<String, MediaType> mapping = Collections.singletonMap("json", MediaType.APPLICATION_JSON);
-		MappingMediaTypeFileExtensionResolver resolver = new MappingMediaTypeFileExtensionResolver(mapping);
-		List<String> extensions = resolver.resolveFileExtensions(MediaType.TEXT_HTML);
+		List<String> extensions = this.resolver.resolveFileExtensions(MediaType.TEXT_HTML);
 
-		assertThat(extensions.isEmpty()).isTrue();
+		assertThat(extensions).isEmpty();
 	}
 
 	/**
@@ -58,9 +58,7 @@ public class MappingMediaTypeFileExtensionResolverTests {
 	 */
 	@Test
 	public void lookupMediaTypeCaseInsensitive() {
-		Map<String, MediaType> mapping = Collections.singletonMap("json", MediaType.APPLICATION_JSON);
-		MappingMediaTypeFileExtensionResolver resolver = new MappingMediaTypeFileExtensionResolver(mapping);
-		MediaType mediaType = resolver.lookupMediaType("JSON");
+		MediaType mediaType = this.resolver.lookupMediaType("JSON");
 
 		assertThat(mediaType).isEqualTo(MediaType.APPLICATION_JSON);
 	}