Add MediaType.APPLICATION_JSON_UTF8

Add new MediaType.APPLICATION_JSON_UTF8 and
MediaType.APPLICATION_JSON_UTF8_VALUE constants for
"application/json;charset=UTF-8" content type in order to make it
easier to override @RequestMapping "produces" attribute without
losing the default JSON charset (UTF-8).

Issue: SPR-13600

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

@@ -40,6 +40,7 @@ import org.springframework.util.comparator.CompoundComparator;
  * @author Arjen Poutsma
  * @author Juergen Hoeller
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  * @since 3.0
  * @see <a href="http://tools.ietf.org/html/rfc7231#section-3.1.1.1">HTTP 1.1: Semantics
  * and Content, section 3.1.1.1</a>
@@ -80,14 +81,26 @@ public class MediaType extends MimeType implements Serializable {
 
 	/**
 	 * Public constant media type for {@code application/json}.
-	 * */
+	 * @see #APPLICATION_JSON_UTF8
+	 */
 	public final static MediaType APPLICATION_JSON;
 
 	/**
 	 * A String equivalent of {@link MediaType#APPLICATION_JSON}.
+	 * @see #APPLICATION_JSON_UTF8_VALUE
 	 */
 	public final static String APPLICATION_JSON_VALUE = "application/json";
 
+	/**
+	 * Public constant media type for {@code application/json;charset=UTF-8}.
+	 */
+	public final static MediaType APPLICATION_JSON_UTF8;
+
+	/**
+	 * A String equivalent of {@link MediaType#APPLICATION_JSON_UTF8}.
+	 */
+	public final static String APPLICATION_JSON_UTF8_VALUE = APPLICATION_JSON_VALUE + ";charset=UTF-8";
+
 	/**
 	 * Public constant media type for {@code application/octet-stream}.
 	 *  */
@@ -197,6 +210,7 @@ public class MediaType extends MimeType implements Serializable {
 		APPLICATION_ATOM_XML = valueOf(APPLICATION_ATOM_XML_VALUE);
 		APPLICATION_FORM_URLENCODED = valueOf(APPLICATION_FORM_URLENCODED_VALUE);
 		APPLICATION_JSON = valueOf(APPLICATION_JSON_VALUE);
+		APPLICATION_JSON_UTF8 = valueOf(APPLICATION_JSON_UTF8_VALUE);
 		APPLICATION_OCTET_STREAM = valueOf(APPLICATION_OCTET_STREAM_VALUE);
 		APPLICATION_XHTML_XML = valueOf(APPLICATION_XHTML_XML_VALUE);
 		APPLICATION_XML = valueOf(APPLICATION_XML_VALUE);

spring-web/src/main/java/org/springframework/http/converter/json/GsonHttpMessageConverter.java

@@ -45,7 +45,8 @@ import org.springframework.util.Assert;
  * {@link Gson} class.
  *
  * <p>This converter can be used to bind to typed beans or untyped {@code HashMap}s.
- * By default, it supports {@code application/json} and {@code application/*+json}.
+ * By default, it supports {@code application/json} and {@code application/*+json} with
+ * {@code UTF-8} character set.
  *
  * <p>Tested against Gson 2.3; compatible with Gson 2.0 and higher.
  *
@@ -69,8 +70,7 @@ public class GsonHttpMessageConverter extends AbstractGenericHttpMessageConverte
 	 * Construct a new {@code GsonHttpMessageConverter}.
 	 */
 	public GsonHttpMessageConverter() {
-		super(new MediaType("application", "json", DEFAULT_CHARSET),
+		super(MediaType.APPLICATION_JSON_UTF8, new MediaType("application", "*+json", DEFAULT_CHARSET));
-				new MediaType("application", "*+json", DEFAULT_CHARSET));
 	}
 
 

spring-web/src/main/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverter.java

@@ -63,7 +63,7 @@ public class MappingJackson2HttpMessageConverter extends AbstractJackson2HttpMes
 	 * @see Jackson2ObjectMapperBuilder#json()
 	 */
 	public MappingJackson2HttpMessageConverter(ObjectMapper objectMapper) {
-		super(objectMapper, new MediaType("application", "json", DEFAULT_CHARSET),
+		super(objectMapper, MediaType.APPLICATION_JSON_UTF8,
 				new MediaType("application", "*+json", DEFAULT_CHARSET));
 	}
 

src/asciidoc/web-mvc.adoc

@@ -1028,7 +1028,7 @@ condition. For example:
 [subs="verbatim,quotes"]
 ----
 	@Controller
-	@RequestMapping(path = "/pets/{petId}", method = RequestMethod.GET, **produces="application/json; charset=UTF-8"**)
+	@RequestMapping(path = "/pets/{petId}", method = RequestMethod.GET, **produces = MediaType.APPLICATION_JSON_UTF8_VALUE**)
 	@ResponseBody
 	public Pet getPet(@PathVariable String petId, Model model) {
 		// implementation omitted
@@ -3855,7 +3855,7 @@ When writing error information, the status code and the error message set on the
 	@Controller
 	public class ErrorController {
 
-		@RequestMapping(path="/error", produces="application/json; charset=UTF-8")
+		@RequestMapping(path = "/error", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
 		@ResponseBody
 		public Map<String, Object> handle(HttpServletRequest request) {