Support HTTP range requests in MVC Controllers

Prior to this commit, HTTP Range requests were only supported by the
ResourceHttpRequestHandler when serving static resources.

This commit improves the `HttpEntityMethodProcessor` and
the `RequestResponseBodyMethodProcessor`. They now extract
`ResourceRegion`s from the `Resource` instance returned by the
Controller and let the Resource-related message converters
handle the writing of the resource (including partial writes).

Controller methods can now handle Range requests for
return types that extend Resource or HttpEntity:

    @RequestMapping("/example/video.mp4")
    public Resource handler() { }

    @RequestMapping("/example/video.mp4")
    public HttpEntity<Resource> handler() { }

Issue: SPR-15789, SPR-13834

spring-webmvc/src/main/java/org/springframework/web/servlet/config/AnnotationDrivenBeanDefinitionParser.java

@@ -44,6 +44,7 @@
 import org.springframework.http.converter.ByteArrayHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.ResourceHttpMessageConverter;
+import org.springframework.http.converter.ResourceRegionHttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.cbor.MappingJackson2CborHttpMessageConverter;
 import org.springframework.http.converter.feed.AtomFeedHttpMessageConverter;
@@ -579,6 +580,7 @@ private ManagedList<?> getMessageConverters(Element element, @Nullable Object so
 			messageConverters.add(stringConverterDef);
 
 			messageConverters.add(createConverterDefinition(ResourceHttpMessageConverter.class, source));
+			messageConverters.add(createConverterDefinition(ResourceRegionHttpMessageConverter.class, source));
 			messageConverters.add(createConverterDefinition(SourceHttpMessageConverter.class, source));
 			messageConverters.add(createConverterDefinition(AllEncompassingFormHttpMessageConverter.class, source));
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -41,6 +41,7 @@
 import org.springframework.http.converter.ByteArrayHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.ResourceHttpMessageConverter;
+import org.springframework.http.converter.ResourceRegionHttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.cbor.MappingJackson2CborHttpMessageConverter;
 import org.springframework.http.converter.feed.AtomFeedHttpMessageConverter;
@@ -790,6 +791,7 @@ protected final void addDefaultHttpMessageConverters(List<HttpMessageConverter<?
 		messageConverters.add(new ByteArrayHttpMessageConverter());
 		messageConverters.add(stringConverter);
 		messageConverters.add(new ResourceHttpMessageConverter());
+		messageConverters.add(new ResourceRegionHttpMessageConverter());
 		messageConverters.add(new SourceHttpMessageConverter<>());
 		messageConverters.add(new AllEncompassingFormHttpMessageConverter());
 

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

@@ -30,10 +30,15 @@
 import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.core.MethodParameter;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.ResourceRegion;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpOutputMessage;
+import org.springframework.http.HttpRange;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
@@ -75,6 +80,9 @@ public abstract class AbstractMessageConverterMethodProcessor extends AbstractMe
 
 	private static final MediaType MEDIA_TYPE_APPLICATION = new MediaType("application");
 
+	private static final Type RESOURCE_REGION_LIST_TYPE =
+			new ParameterizedTypeReference<List<ResourceRegion>>() { }.getType();
+
 
 	private static final UrlPathHelper decodingUrlPathHelper = new UrlPathHelper();
 
@@ -183,6 +191,24 @@ protected <T> void writeWithMessageConverters(@Nullable T value, MethodParameter
 			valueType = getReturnValueType(outputValue, returnType);
 			declaredType = getGenericType(returnType);
 		}
+
+		if (isResourceType(value, returnType)) {
+			outputMessage.getHeaders().set(HttpHeaders.ACCEPT_RANGES, "bytes");
+			if (value != null && inputMessage.getHeaders().getFirst(HttpHeaders.RANGE) != null) {
+				Resource resource = (Resource) value;
+				try {
+					List<HttpRange> httpRanges = inputMessage.getHeaders().getRange();
+					outputMessage.getServletResponse().setStatus(HttpStatus.PARTIAL_CONTENT.value());
+					outputValue = HttpRange.toResourceRegions(httpRanges, resource);
+					valueType = outputValue.getClass();
+					declaredType = RESOURCE_REGION_LIST_TYPE;
+				}
+				catch (IllegalArgumentException ex) {
+					outputMessage.getHeaders().set(HttpHeaders.CONTENT_RANGE, "bytes */" + resource.contentLength());
+					outputMessage.getServletResponse().setStatus(HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE.value());
+				}
+			}
+		}
 
 		HttpServletRequest request = inputMessage.getServletRequest();
 		List<MediaType> requestedMediaTypes = getAcceptableMediaTypes(request);
@@ -266,6 +292,13 @@ protected Class<?> getReturnValueType(@Nullable Object value, MethodParameter re
 		return (value != null ? value.getClass() : returnType.getParameterType());
 	}
 
+	/**
+	 * Return whether the returned value or the declared return type extend {@link Resource}
+	 */
+	protected boolean isResourceType(@Nullable Object value, MethodParameter returnType) {
+		return Resource.class.isAssignableFrom(value != null ? value.getClass() : returnType.getParameterType());
+	}
+
 	/**
 	 * Return the generic type of the {@code returnType} (or of the nested type
 	 * if it is an {@link HttpEntity}).

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandler.java

@@ -387,14 +387,8 @@ public void handleRequest(HttpServletRequest request, HttpServletResponse respon
 			try {
 				List<HttpRange> httpRanges = inputMessage.getHeaders().getRange();
 				response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
-				if (httpRanges.size() == 1) {
-					ResourceRegion resourceRegion = httpRanges.get(0).toResourceRegion(resource);
-					this.resourceRegionHttpMessageConverter.write(resourceRegion, mediaType, outputMessage);
-				}
-				else {
 					this.resourceRegionHttpMessageConverter.write(
 							HttpRange.toResourceRegions(httpRanges, resource), mediaType, outputMessage);
-				}
 			}
 			catch (IllegalArgumentException ex) {
 				response.setHeader("Content-Range", "bytes */" + resource.contentLength());

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupportTests.java

@@ -175,7 +175,7 @@ public void requestMappingHandlerAdapter() throws Exception {
 		ApplicationContext context = initContext(WebConfig.class);
 		RequestMappingHandlerAdapter adapter = context.getBean(RequestMappingHandlerAdapter.class);
 		List<HttpMessageConverter<?>> converters = adapter.getMessageConverters();
-		assertEquals(11, converters.size());
+		assertEquals(12, converters.size());
 		converters.stream()
 				.filter(converter -> converter instanceof AbstractJackson2HttpMessageConverter)
 				.forEach(converter -> {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/HttpEntityMethodProcessorMockTests.java

@@ -20,10 +20,9 @@
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.time.ZoneId;
-import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
-import java.util.List;
 
 import org.junit.Before;
 import org.junit.Rule;
@@ -82,6 +81,8 @@ public class HttpEntityMethodProcessorMockTests {
 
 	private HttpMessageConverter<Resource> resourceMessageConverter;
 
+	private HttpMessageConverter<Object> resourceRegionMessageConverter;
+
 	private MethodParameter paramHttpEntity;
 
 	private MethodParameter paramRequestEntity;
@@ -119,12 +120,11 @@ public void setup() throws Exception {
 		given(stringHttpMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
 		resourceMessageConverter = mock(HttpMessageConverter.class);
 		given(resourceMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.ALL));
-		List<HttpMessageConverter<?>> converters = new ArrayList<>();
-		converters.add(stringHttpMessageConverter);
-		converters.add(resourceMessageConverter);
-		processor = new HttpEntityMethodProcessor(converters);
-		reset(stringHttpMessageConverter);
-		reset(resourceMessageConverter);
+		resourceRegionMessageConverter = mock(HttpMessageConverter.class);
+		given(resourceRegionMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.ALL));
+
+		processor = new HttpEntityMethodProcessor(
+				Arrays.asList(stringHttpMessageConverter, resourceMessageConverter, resourceRegionMessageConverter));
 
 		Method handle1 = getClass().getMethod("handle1", HttpEntity.class, ResponseEntity.class,
 				Integer.TYPE, RequestEntity.class);
@@ -497,6 +497,39 @@ public void shouldHandleResource() throws Exception {
 		assertEquals(200, servletResponse.getStatus());
 	}
 
+	@Test
+	public void shouldHandleResourceByteRange() throws Exception {
+		ResponseEntity<Resource> returnValue = ResponseEntity
+				.ok(new ByteArrayResource("Content".getBytes(StandardCharsets.UTF_8)));
+		servletRequest.addHeader("Range", "bytes=0-5");
+
+		given(resourceRegionMessageConverter.canWrite(any(), eq(null))).willReturn(true);
+		given(resourceRegionMessageConverter.canWrite(any(), eq(MediaType.APPLICATION_OCTET_STREAM))).willReturn(true);
+
+		processor.handleReturnValue(returnValue, returnTypeResponseEntityResource, mavContainer, webRequest);
+
+		then(resourceRegionMessageConverter).should(times(1)).write(
+				anyCollection(), eq(MediaType.APPLICATION_OCTET_STREAM),
+				argThat(outputMessage -> outputMessage.getHeaders().getFirst(HttpHeaders.ACCEPT_RANGES) == "bytes"));
+		assertEquals(206, servletResponse.getStatus());
+	}
+
+	@Test
+	public void handleReturnTypeResourceIllegalByteRange() throws Exception {
+		ResponseEntity<Resource> returnValue = ResponseEntity
+				.ok(new ByteArrayResource("Content".getBytes(StandardCharsets.UTF_8)));
+		servletRequest.addHeader("Range", "illegal");
+
+		given(resourceRegionMessageConverter.canWrite(any(), eq(null))).willReturn(true);
+		given(resourceRegionMessageConverter.canWrite(any(), eq(MediaType.APPLICATION_OCTET_STREAM))).willReturn(true);
+
+		processor.handleReturnValue(returnValue, returnTypeResponseEntityResource, mavContainer, webRequest);
+
+		then(resourceRegionMessageConverter).should(never()).write(
+				anyCollection(), eq(MediaType.APPLICATION_OCTET_STREAM), any(HttpOutputMessage.class));
+		assertEquals(416, servletResponse.getStatus());
+	}
+
 	@Test  //SPR-14767
 	public void shouldHandleValidatorHeadersInPutResponses() throws Exception {
 		servletRequest.setMethod("PUT");

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestResponseBodyMethodProcessorMockTests.java

@@ -22,6 +22,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+
 import javax.validation.Valid;
 import javax.validation.constraints.NotNull;
 
@@ -31,6 +32,7 @@
 import org.springframework.core.MethodParameter;
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.Resource;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpInputMessage;
 import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
@@ -71,6 +73,8 @@ public class RequestResponseBodyMethodProcessorMockTests {
 
 	private HttpMessageConverter<Resource> resourceMessageConverter;
 
+	private HttpMessageConverter<Object> resourceRegionMessageConverter;
+
 	private RequestResponseBodyMethodProcessor processor;
 
 	private ModelAndViewContainer mavContainer;
@@ -97,11 +101,13 @@ public class RequestResponseBodyMethodProcessorMockTests {
 	public void setup() throws Exception {
 		stringMessageConverter = mock(HttpMessageConverter.class);
 		given(stringMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
-
 		resourceMessageConverter = mock(HttpMessageConverter.class);
 		given(resourceMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.ALL));
+		resourceRegionMessageConverter = mock(HttpMessageConverter.class);
+		given(resourceRegionMessageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.ALL));
 
-		processor = new RequestResponseBodyMethodProcessor(Arrays.asList(stringMessageConverter, resourceMessageConverter));
+		processor = new RequestResponseBodyMethodProcessor(
+				Arrays.asList(stringMessageConverter, resourceMessageConverter, resourceRegionMessageConverter));
 
 		mavContainer = new ModelAndViewContainer();
 		servletRequest = new MockHttpServletRequest();
@@ -364,6 +370,37 @@ public void handleReturnValueMediaTypeSuffix() throws Exception {
 		verify(stringMessageConverter).write(eq(body), eq(accepted), isA(HttpOutputMessage.class));
 	}
 
+	@Test
+	public void handleReturnTypeResourceByteRange() throws Exception {
+		Resource returnValue = new ByteArrayResource("Content".getBytes(StandardCharsets.UTF_8));
+		servletRequest.addHeader("Range", "bytes=0-5");
+
+		given(resourceRegionMessageConverter.canWrite(any(), eq(null))).willReturn(true);
+		given(resourceRegionMessageConverter.canWrite(any(), eq(MediaType.APPLICATION_OCTET_STREAM))).willReturn(true);
+
+		processor.handleReturnValue(returnValue, returnTypeResource, mavContainer, webRequest);
+
+		then(resourceRegionMessageConverter).should(times(1)).write(
+				anyCollection(), eq(MediaType.APPLICATION_OCTET_STREAM),
+				argThat(outputMessage -> outputMessage.getHeaders().getFirst(HttpHeaders.ACCEPT_RANGES) == "bytes"));
+		assertEquals(206, servletResponse.getStatus());
+	}
+
+	@Test
+	public void handleReturnTypeResourceIllegalByteRange() throws Exception {
+		Resource returnValue = new ByteArrayResource("Content".getBytes(StandardCharsets.UTF_8));
+		servletRequest.addHeader("Range", "illegal");
+
+		given(resourceRegionMessageConverter.canWrite(any(), eq(null))).willReturn(true);
+		given(resourceRegionMessageConverter.canWrite(any(), eq(MediaType.APPLICATION_OCTET_STREAM))).willReturn(true);
+
+		processor.handleReturnValue(returnValue, returnTypeResource, mavContainer, webRequest);
+
+		then(resourceRegionMessageConverter).should(never()).write(
+				anyCollection(), eq(MediaType.APPLICATION_OCTET_STREAM), any(HttpOutputMessage.class));
+		assertEquals(416, servletResponse.getStatus());
+	}
+
 
 	@SuppressWarnings("unused")
 	@ResponseBody