Support for byte-range requests in WebMvc.fn

This commit introduces support for byte-range requests in Servlet
Functional endpoints.

Closes gh-24562

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -41,9 +41,13 @@ import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 
 import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.core.io.InputStreamResource;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.ResourceRegion;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpRange;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
@@ -70,6 +74,9 @@ final class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T>
 	private static final boolean reactiveStreamsPresent = ClassUtils.isPresent(
 			"org.reactivestreams.Publisher", DefaultEntityResponseBuilder.class.getClassLoader());
 
+	private static final Type RESOURCE_REGION_LIST_TYPE =
+				new ParameterizedTypeReference<List<ResourceRegion>>() { }.getType();
+
 
 	private final T entity;
 
@@ -245,6 +252,11 @@ final class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T>
 			this.entityType = entityType;
 		}
 
+		private static <T> boolean isResource(T entity) {
+			return !(entity instanceof InputStreamResource) &&
+					(entity instanceof Resource);
+		}
+
 		@Override
 		public T entity() {
 			return this.entity;
@@ -267,13 +279,33 @@ final class DefaultEntityResponseBuilder<T> implements EntityResponse.Builder<T>
 			ServletServerHttpResponse serverResponse = new ServletServerHttpResponse(response);
 			MediaType contentType = getContentType(response);
 			Class<?> entityClass = entity.getClass();
+			Type entityType = this.entityType;
+
+			if (entityClass != InputStreamResource.class && Resource.class.isAssignableFrom(entityClass)) {
+				serverResponse.getHeaders().set(HttpHeaders.ACCEPT_RANGES, "bytes");
+				String rangeHeader = request.getHeader(HttpHeaders.RANGE);
+				if (rangeHeader != null) {
+					Resource resource = (Resource) entity;
+					try {
+						List<HttpRange> httpRanges = HttpRange.parseRanges(rangeHeader);
+						serverResponse.getServletResponse().setStatus(HttpStatus.PARTIAL_CONTENT.value());
+						entity = HttpRange.toResourceRegions(httpRanges, resource);
+						entityClass = entity.getClass();
+						entityType = RESOURCE_REGION_LIST_TYPE;
+					}
+					catch (IllegalArgumentException ex) {
+						serverResponse.getHeaders().set(HttpHeaders.CONTENT_RANGE, "bytes */" + resource.contentLength());
+						serverResponse.getServletResponse().setStatus(HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE.value());
+					}
+				}
+			}
 
 			for (HttpMessageConverter<?> messageConverter : context.messageConverters()) {
 				if (messageConverter instanceof GenericHttpMessageConverter<?>) {
 					GenericHttpMessageConverter<Object> genericMessageConverter =
 							(GenericHttpMessageConverter<Object>) messageConverter;
-					if (genericMessageConverter.canWrite(this.entityType, entityClass, contentType)) {
+					if (genericMessageConverter.canWrite(entityType, entityClass, contentType)) {
-						genericMessageConverter.write(entity, this.entityType, contentType, serverResponse);
+						genericMessageConverter.write(entity, entityType, contentType, serverResponse);
 						return;
 					}
 				}

spring-webmvc/src/test/java/org/springframework/web/servlet/function/ResourceHandlerFunctionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -17,7 +17,9 @@
 package org.springframework.web.servlet.function;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.file.Files;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
@@ -29,11 +31,13 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.ResourceHttpMessageConverter;
+import org.springframework.http.converter.ResourceRegionHttpMessageConverter;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.testfixture.servlet.MockHttpServletResponse;
@@ -56,10 +60,11 @@ public class ResourceHandlerFunctionTests {
 	@BeforeEach
 	public void createContext() {
 		this.messageConverter = new ResourceHttpMessageConverter();
+		ResourceRegionHttpMessageConverter regionConverter = new ResourceRegionHttpMessageConverter();
 		this.context = new ServerResponse.Context() {
 			@Override
 			public List<HttpMessageConverter<?>> messageConverters() {
-				return Collections.singletonList(messageConverter);
+				return Arrays.asList(messageConverter, regionConverter);
 			}
 
 		};
@@ -73,8 +78,7 @@ public class ResourceHandlerFunctionTests {
 
 		ServerResponse response = this.handlerFunction.handle(request);
 		assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
-		boolean condition = response instanceof EntityResponse;
+		assertThat(response).isInstanceOf(EntityResponse.class);
-		assertThat(condition).isTrue();
 		@SuppressWarnings("unchecked")
 		EntityResponse<Resource> entityResponse = (EntityResponse<Resource>) response;
 		assertThat(entityResponse.entity()).isEqualTo(this.resource);
@@ -91,6 +95,61 @@ public class ResourceHandlerFunctionTests {
 		assertThat(servletResponse.getContentLength()).isEqualTo(this.resource.contentLength());
 	}
 
+	@Test
+	public void getRange() throws IOException, ServletException {
+		MockHttpServletRequest servletRequest = new MockHttpServletRequest("GET", "/");
+		servletRequest.addHeader("Range", "bytes=0-5");
+		ServerRequest request = new DefaultServerRequest(servletRequest, Collections.singletonList(messageConverter));
+
+		ServerResponse response = this.handlerFunction.handle(request);
+		assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(response).isInstanceOf(EntityResponse.class);
+		@SuppressWarnings("unchecked")
+		EntityResponse<Resource> entityResponse = (EntityResponse<Resource>) response;
+		assertThat(entityResponse.entity()).isEqualTo(this.resource);
+
+		MockHttpServletResponse servletResponse = new MockHttpServletResponse();
+		ModelAndView mav = response.writeTo(servletRequest, servletResponse, this.context);
+		assertThat(mav).isNull();
+
+		assertThat(servletResponse.getStatus()).isEqualTo(206);
+		byte[] expectedBytes = new byte[6];
+		try (InputStream is = this.resource.getInputStream()) {
+			is.read(expectedBytes);
+		}
+		byte[] actualBytes = servletResponse.getContentAsByteArray();
+		assertThat(actualBytes).isEqualTo(expectedBytes);
+		assertThat(servletResponse.getContentType()).isEqualTo(MediaType.TEXT_PLAIN_VALUE);
+		assertThat(servletResponse.getContentLength()).isEqualTo(6);
+		assertThat(servletResponse.getHeader(HttpHeaders.ACCEPT_RANGES)).isEqualTo("bytes");
+	}
+
+	@Test
+	public void getInvalidRange() throws IOException, ServletException {
+		MockHttpServletRequest servletRequest = new MockHttpServletRequest("GET", "/");
+		servletRequest.addHeader("Range", "bytes=0-10, 0-10, 0-10, 0-10, 0-10, 0-10");
+		ServerRequest request = new DefaultServerRequest(servletRequest, Collections.singletonList(messageConverter));
+
+		ServerResponse response = this.handlerFunction.handle(request);
+		assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(response).isInstanceOf(EntityResponse.class);
+		@SuppressWarnings("unchecked")
+		EntityResponse<Resource> entityResponse = (EntityResponse<Resource>) response;
+		assertThat(entityResponse.entity()).isEqualTo(this.resource);
+
+		MockHttpServletResponse servletResponse = new MockHttpServletResponse();
+		ModelAndView mav = response.writeTo(servletRequest, servletResponse, this.context);
+		assertThat(mav).isNull();
+
+		assertThat(servletResponse.getStatus()).isEqualTo(416);
+		byte[] expectedBytes = Files.readAllBytes(this.resource.getFile().toPath());
+		byte[] actualBytes = servletResponse.getContentAsByteArray();
+		assertThat(actualBytes).isEqualTo(expectedBytes);
+		assertThat(servletResponse.getContentType()).isEqualTo(MediaType.TEXT_PLAIN_VALUE);
+		assertThat(servletResponse.getContentLength()).isEqualTo(this.resource.contentLength());
+		assertThat(servletResponse.getHeader(HttpHeaders.ACCEPT_RANGES)).isEqualTo("bytes");
+	}
+
 	@Test
 	public void head() throws IOException, ServletException {
 		MockHttpServletRequest servletRequest = new MockHttpServletRequest("HEAD", "/");
@@ -98,8 +157,7 @@ public class ResourceHandlerFunctionTests {
 
 		ServerResponse response = this.handlerFunction.handle(request);
 		assertThat(response.statusCode()).isEqualTo(HttpStatus.OK);
-		boolean condition = response instanceof EntityResponse;
+		assertThat(response).isInstanceOf(EntityResponse.class);
-		assertThat(condition).isTrue();
 		@SuppressWarnings("unchecked")
 		EntityResponse<Resource> entityResponse = (EntityResponse<Resource>) response;
 		assertThat(entityResponse.entity().getFilename()).isEqualTo(this.resource.getFilename());
@@ -136,4 +194,5 @@ public class ResourceHandlerFunctionTests {
 		assertThat(actualBytes.length).isEqualTo(0);
 	}
 
+
 }