Media types by Class for HttpMessageConverter

See gh-26212

Author: rstoyanchev

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -17,6 +17,7 @@
 package org.springframework.http.converter;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
 
 import org.springframework.http.HttpInputMessage;
@@ -53,11 +54,30 @@ public interface HttpMessageConverter<T> {
 	boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType);
 
 	/**
-	 * Return the list of {@link MediaType} objects supported by this converter.
-	 * @return the list of supported media types, potentially an immutable copy
+	 * Return the list of media types supported by this converter. The list may
+	 * not apply to every possible target element type and calls to this method
+	 * should typically be guarded via {@link #canWrite(Class, MediaType)
+	 * canWrite(clazz, null}. The list may also exclude MIME types supported
+	 * only for a specific class. Alternatively, use
+	 * {@link #getSupportedMediaTypes(Class)} for a more precise list.
+	 * @return the list of supported media types
 	 */
 	List<MediaType> getSupportedMediaTypes();
 
+	/**
+	 * Return the list of media types supported by this converter for the given
+	 * class. The list may differ from {@link #getSupportedMediaTypes()} if the
+	 * converter doesn't support given Class or if it support it only for a
+	 * subset of media types.
+	 * @param clazz the type of class to check
+	 * @return the list of media types supported for the given class
+	 * @since 5.3.4
+	 */
+	default List<MediaType> getSupportedMediaTypes(Class<?> clazz) {
+		return (canRead(clazz, null) || canWrite(clazz, null) ?
+				getSupportedMediaTypes() : Collections.emptyList());
+	}
+
 	/**
 	 * Read an object of the given type from the given input message, and returns it.
 	 * @param clazz the type of object to return. This type must have previously been passed to the

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -23,6 +23,7 @@
 import java.lang.reflect.Type;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedHashMap;
@@ -194,6 +195,18 @@ public Map<MediaType, ObjectMapper> getObjectMappersForType(Class<?> clazz) {
 		return Collections.emptyMap();
 	}
 
+	@Override
+	public List<MediaType> getSupportedMediaTypes(Class<?> clazz) {
+		List<MediaType> result = null;
+		for (Map.Entry<Class<?>, Map<MediaType, ObjectMapper>> entry : getObjectMapperRegistrations().entrySet()) {
+			if (entry.getKey().isAssignableFrom(clazz)) {
+				result = (result != null ? result : new ArrayList<>(entry.getValue().size()));
+				result.addAll(entry.getValue().keySet());
+			}
+		}
+		return (CollectionUtils.isEmpty(result) ? getSupportedMediaTypes() : result);
+	}
+
 	private Map<Class<?>, Map<MediaType, ObjectMapper>> getObjectMapperRegistrations() {
 		return (this.objectMapperRegistrations != null ? this.objectMapperRegistrations : Collections.emptyMap());
 	}

spring-web/src/main/java/org/springframework/web/client/RestTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -17,6 +17,7 @@
 package org.springframework.web.client;
 
 import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.net.URI;
 import java.util.ArrayList;
@@ -885,7 +886,7 @@ public void doWithRequest(ClientHttpRequest request) throws IOException {
 			if (this.responseType != null) {
 				List<MediaType> allSupportedMediaTypes = getMessageConverters().stream()
 						.filter(converter -> canReadResponse(this.responseType, converter))
-						.flatMap(this::getSupportedMediaTypes)
+						.flatMap((HttpMessageConverter<?> converter) -> getSupportedMediaTypes(this.responseType, converter))
 						.distinct()
 						.sorted(MediaType.SPECIFICITY_COMPARATOR)
 						.collect(Collectors.toList());
@@ -908,8 +909,10 @@ else if (converter instanceof GenericHttpMessageConverter) {
 			return false;
 		}
 
-		private Stream<MediaType> getSupportedMediaTypes(HttpMessageConverter<?> messageConverter) {
-			return messageConverter.getSupportedMediaTypes()
+		private Stream<MediaType> getSupportedMediaTypes(Type type, HttpMessageConverter<?> converter) {
+			Type rawType = (type instanceof ParameterizedType ? ((ParameterizedType) type).getRawType() : type);
+			Class<?> clazz = (rawType instanceof Class ? (Class<?>) rawType : null);
+			return (clazz != null ? converter.getSupportedMediaTypes(clazz) : converter.getSupportedMediaTypes())
 					.stream()
 					.map(mediaType -> {
 						if (mediaType.getCharset() != null) {

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -109,6 +109,22 @@ public void canReadAndWriteMicroformats() {
 		assertThat(converter.canWrite(MyBean.class, new MediaType("application", "vnd.test-micro-type+json"))).isTrue();
 	}
 
+	@Test
+	public void getSupportedMediaTypes() {
+		MediaType[] defaultMediaTypes = {MediaType.APPLICATION_JSON, MediaType.parseMediaType("application/*+json")};
+		assertThat(converter.getSupportedMediaTypes()).containsExactly(defaultMediaTypes);
+		assertThat(converter.getSupportedMediaTypes(MyBean.class)).containsExactly(defaultMediaTypes);
+
+		MediaType halJson = MediaType.parseMediaType("application/hal+json");
+		converter.registerObjectMappersForType(MyBean.class, map -> {
+			map.put(halJson, new ObjectMapper());
+			map.put(MediaType.APPLICATION_JSON, new ObjectMapper());
+		});
+
+		assertThat(converter.getSupportedMediaTypes(MyBean.class)).containsExactly(halJson, MediaType.APPLICATION_JSON);
+		assertThat(converter.getSupportedMediaTypes(Map.class)).containsExactly(defaultMediaTypes);
+	}
+
 	@Test
 	public void readTyped() throws IOException {
 		String body = "{" +

spring-web/src/test/java/org/springframework/web/client/RestTemplateTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -232,12 +232,10 @@ void getUnsupportedMediaType() throws Exception {
 	void requestAvoidsDuplicateAcceptHeaderValues() throws Exception {
 		HttpMessageConverter<?> firstConverter = mock(HttpMessageConverter.class);
 		given(firstConverter.canRead(any(), any())).willReturn(true);
-		given(firstConverter.getSupportedMediaTypes())
-				.willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
+		given(firstConverter.getSupportedMediaTypes(any())).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
 		HttpMessageConverter<?> secondConverter = mock(HttpMessageConverter.class);
 		given(secondConverter.canRead(any(), any())).willReturn(true);
-		given(secondConverter.getSupportedMediaTypes())
-				.willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
+		given(secondConverter.getSupportedMediaTypes(any())).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
 
 		HttpHeaders requestHeaders = new HttpHeaders();
 		mockSentRequest(GET, "https://example.com/", requestHeaders);
@@ -651,7 +649,7 @@ void exchangeParameterizedType() throws Exception {
 		template.setMessageConverters(Collections.<HttpMessageConverter<?>>singletonList(converter));
 		ParameterizedTypeReference<List<Integer>> intList = new ParameterizedTypeReference<List<Integer>>() {};
 		given(converter.canRead(intList.getType(), null, null)).willReturn(true);
-		given(converter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
+		given(converter.getSupportedMediaTypes(any())).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
 		given(converter.canWrite(String.class, String.class, null)).willReturn(true);
 
 		HttpHeaders requestHeaders = new HttpHeaders();
@@ -774,8 +772,7 @@ private void mockTextPlainHttpMessageConverter() {
 	private void mockHttpMessageConverter(MediaType mediaType, Class<?> type) {
 		given(converter.canRead(type, null)).willReturn(true);
 		given(converter.canRead(type, mediaType)).willReturn(true);
-		given(converter.getSupportedMediaTypes())
-				.willReturn(Collections.singletonList(mediaType));
+		given(converter.getSupportedMediaTypes(type)).willReturn(Collections.singletonList(mediaType));
 		given(converter.canRead(type, mediaType)).willReturn(true);
 		given(converter.canWrite(type, null)).willReturn(true);
 		given(converter.canWrite(type, mediaType)).willReturn(true);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -339,7 +339,7 @@ private static List<MediaType> producibleMediaTypes(
 
 			return messageConverters.stream()
 					.filter(messageConverter -> messageConverter.canWrite(entityClass, null))
-					.flatMap(messageConverter -> messageConverter.getSupportedMediaTypes().stream())
+					.flatMap(messageConverter -> messageConverter.getSupportedMediaTypes(entityClass).stream())
 					.collect(Collectors.toList());
 		}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -81,8 +81,6 @@ class DefaultServerRequest implements ServerRequest {
 
 	private final List<HttpMessageConverter<?>> messageConverters;
 
-	private final List<MediaType> allSupportedMediaTypes;
-
 	private final MultiValueMap<String, String> params;
 
 	private final Map<String, Object> attributes;
@@ -94,7 +92,6 @@ class DefaultServerRequest implements ServerRequest {
 	public DefaultServerRequest(HttpServletRequest servletRequest, List<HttpMessageConverter<?>> messageConverters) {
 		this.serverHttpRequest = new ServletServerHttpRequest(servletRequest);
 		this.messageConverters = Collections.unmodifiableList(new ArrayList<>(messageConverters));
-		this.allSupportedMediaTypes = allSupportedMediaTypes(messageConverters);
 
 		this.headers = new DefaultRequestHeaders(this.serverHttpRequest.getHeaders());
 		this.params = CollectionUtils.toMultiValueMap(new ServletParametersMap(servletRequest));
@@ -107,13 +104,6 @@ public DefaultServerRequest(HttpServletRequest servletRequest, List<HttpMessageC
 				ServletRequestPathUtils.parseAndCache(servletRequest));
 	}
 
-	private static List<MediaType> allSupportedMediaTypes(List<HttpMessageConverter<?>> messageConverters) {
-		return messageConverters.stream()
-				.flatMap(converter -> converter.getSupportedMediaTypes().stream())
-				.sorted(MediaType.SPECIFICITY_COMPARATOR)
-				.collect(Collectors.toList());
-	}
-
 
 	@Override
 	public String methodName() {
@@ -211,7 +201,14 @@ private <T> T bodyInternal(Type bodyType, Class<?> bodyClass) throws ServletExce
 				return theConverter.read(clazz, this.serverHttpRequest);
 			}
 		}
-		throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);
+		throw new HttpMediaTypeNotSupportedException(contentType, getSupportedMediaTypes(bodyClass));
+	}
+
+	private List<MediaType> getSupportedMediaTypes(Class<?> bodyClass) {
+		return this.messageConverters.stream()
+				.flatMap(converter -> converter.getSupportedMediaTypes(bodyClass).stream())
+				.sorted(MediaType.SPECIFICITY_COMPARATOR)
+				.collect(Collectors.toList());
 	}
 
 	@Override

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -23,7 +23,6 @@
 import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.EnumSet;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -80,8 +79,6 @@ public abstract class AbstractMessageConverterMethodArgumentResolver implements
 
 	protected final List<HttpMessageConverter<?>> messageConverters;
 
-	protected final List<MediaType> allSupportedMediaTypes;
-
 	private final RequestResponseBodyAdviceChain advice;
 
 
@@ -101,26 +98,10 @@ public AbstractMessageConverterMethodArgumentResolver(List<HttpMessageConverter<
 
 		Assert.notEmpty(converters, "'messageConverters' must not be empty");
 		this.messageConverters = converters;
-		this.allSupportedMediaTypes = getAllSupportedMediaTypes(converters);
 		this.advice = new RequestResponseBodyAdviceChain(requestResponseBodyAdvice);
 	}
 
 
-	/**
-	 * Return the media types supported by all provided message converters sorted
-	 * by specificity via {@link MediaType#sortBySpecificity(List)}.
-	 */
-	private static List<MediaType> getAllSupportedMediaTypes(List<HttpMessageConverter<?>> messageConverters) {
-		Set<MediaType> allSupportedMediaTypes = new LinkedHashSet<>();
-		for (HttpMessageConverter<?> messageConverter : messageConverters) {
-			allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
-		}
-		List<MediaType> result = new ArrayList<>(allSupportedMediaTypes);
-		MediaType.sortBySpecificity(result);
-		return Collections.unmodifiableList(result);
-	}
-
-
 	/**
 	 * Return the configured {@link RequestBodyAdvice} and
 	 * {@link RequestBodyAdvice} where each instance may be wrapped as a
@@ -222,7 +203,7 @@ protected <T> Object readWithMessageConverters(HttpInputMessage inputMessage, Me
 					(noContentType && !message.hasBody())) {
 				return null;
 			}
-			throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);
+			throw new HttpMediaTypeNotSupportedException(contentType, getSupportedMediaTypes(targetClass));
 		}
 
 		MediaType selectedContentType = contentType;
@@ -283,6 +264,21 @@ protected boolean isBindExceptionRequired(WebDataBinder binder, MethodParameter
 		return !hasBindingResult;
 	}
 
+	/**
+	 * Return the media types supported by all provided message converters sorted
+	 * by specificity via {@link MediaType#sortBySpecificity(List)}.
+	 * @since 5.3.4
+	 */
+	protected List<MediaType> getSupportedMediaTypes(Class<?> clazz) {
+		Set<MediaType> mediaTypeSet = new LinkedHashSet<>();
+		for (HttpMessageConverter<?> converter : this.messageConverters) {
+			mediaTypeSet.addAll(converter.getSupportedMediaTypes(clazz));
+		}
+		List<MediaType> result = new ArrayList<>(mediaTypeSet);
+		MediaType.sortBySpecificity(result);
+		return result;
+	}
+
 	/**
 	 * Adapt the given argument against the method parameter, if necessary.
 	 * @param arg the resolved argument

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodProcessor.java

@@ -299,7 +299,7 @@ else if (mediaType.isPresentIn(ALL_APPLICATION_MEDIA_TYPES)) {
 				throw new HttpMessageNotWritableException(
 						"No converter for [" + valueType + "] with preset Content-Type '" + contentType + "'");
 			}
-			throw new HttpMediaTypeNotAcceptableException(this.allSupportedMediaTypes);
+			throw new HttpMediaTypeNotAcceptableException(getSupportedMediaTypes(body.getClass()));
 		}
 	}
 
@@ -361,23 +361,18 @@ protected List<MediaType> getProducibleMediaTypes(
 		if (!CollectionUtils.isEmpty(mediaTypes)) {
 			return new ArrayList<>(mediaTypes);
 		}
-		else if (!this.allSupportedMediaTypes.isEmpty()) {
-			List<MediaType> result = new ArrayList<>();
-			for (HttpMessageConverter<?> converter : this.messageConverters) {
-				if (converter instanceof GenericHttpMessageConverter && targetType != null) {
-					if (((GenericHttpMessageConverter<?>) converter).canWrite(targetType, valueClass, null)) {
-						result.addAll(converter.getSupportedMediaTypes());
-					}
-				}
-				else if (converter.canWrite(valueClass, null)) {
-					result.addAll(converter.getSupportedMediaTypes());
+		List<MediaType> result = new ArrayList<>();
+		for (HttpMessageConverter<?> converter : this.messageConverters) {
+			if (converter instanceof GenericHttpMessageConverter && targetType != null) {
+				if (((GenericHttpMessageConverter<?>) converter).canWrite(targetType, valueClass, null)) {
+					result.addAll(converter.getSupportedMediaTypes(valueClass));
 				}
 			}
-			return result;
-		}
-		else {
-			return Collections.singletonList(MediaType.ALL);
+			else if (converter.canWrite(valueClass, null)) {
+				result.addAll(converter.getSupportedMediaTypes(valueClass));
+			}
 		}
+		return (result.isEmpty() ? Collections.singletonList(MediaType.ALL) : result);
 	}
 
 	private List<MediaType> getAcceptableMediaTypes(HttpServletRequest request)