Fix default content-type for ResourceRegion HTTP responses

Prior to this commit, the `ResourceRegionHttpMessageConverter` would
rely on the default implementation of `getDefaultContentType` to guess
the default Content-Type of the resource region to be written to the
HTTP response. That implementation fetches the first media type
provided in the HTTP request "Accept" header.

This behavior is not correct when converting resources and this commits
aligns this converter with the `ResourceHttpMessageConverter` which uses
JAF to guess the correct Content-Type of the given resource, or just
returns "application/octet-stream" as a default value.

Issue: SPR-15041

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

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2017 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.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package org.springframework.http.converter;
+
+import java.io.IOException;
+import java.io.InputStream;
+import javax.activation.FileTypeMap;
+import javax.activation.MimetypesFileTypeMap;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+import org.springframework.http.MediaType;
+import org.springframework.util.StringUtils;
+
+/**
+ * Resolve {@code MediaType} for a given {@link Resource} using JAF.
+ */
+class ActivationMediaTypeFactory {
+
+	private static final FileTypeMap fileTypeMap;
+
+	static {
+		fileTypeMap = loadFileTypeMapFromContextSupportModule();
+	}
+
+	private static FileTypeMap loadFileTypeMapFromContextSupportModule() {
+		// See if we can find the extended mime.types from the context-support module...
+		Resource mappingLocation = new ClassPathResource("org/springframework/mail/javamail/mime.types");
+		if (mappingLocation.exists()) {
+			InputStream inputStream = null;
+			try {
+				inputStream = mappingLocation.getInputStream();
+				return new MimetypesFileTypeMap(inputStream);
+			}
+			catch (IOException ex) {
+				// ignore
+			}
+			finally {
+				if (inputStream != null) {
+					try {
+						inputStream.close();
+					}
+					catch (IOException ex) {
+						// ignore
+					}
+				}
+			}
+		}
+		return FileTypeMap.getDefaultFileTypeMap();
+	}
+
+	public static MediaType getMediaType(Resource resource) {
+		String filename = resource.getFilename();
+		if (filename != null) {
+			String mediaType = fileTypeMap.getContentType(filename);
+			if (StringUtils.hasText(mediaType)) {
+				return MediaType.parseMediaType(mediaType);
+			}
+		}
+		return null;
+	}
+}

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

@@ -19,11 +19,8 @@ package org.springframework.http.converter;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
-import javax.activation.FileTypeMap;
-import javax.activation.MimetypesFileTypeMap;
 
 import org.springframework.core.io.ByteArrayResource;
-import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.InputStreamResource;
 import org.springframework.core.io.Resource;
 import org.springframework.http.HttpInputMessage;
@@ -31,7 +28,6 @@ import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StreamUtils;
-import org.springframework.util.StringUtils;
 
 /**
  * Implementation of {@link HttpMessageConverter} that can read and write {@link Resource Resources}
@@ -131,54 +127,4 @@ public class ResourceHttpMessageConverter extends AbstractHttpMessageConverter<R
 		}
 	}
 
-
-	/**
-	 * Inner class to avoid a hard-coded JAF dependency.
-	 */
-	private static class ActivationMediaTypeFactory {
-
-		private static final FileTypeMap fileTypeMap;
-
-		static {
-			fileTypeMap = loadFileTypeMapFromContextSupportModule();
-		}
-
-		private static FileTypeMap loadFileTypeMapFromContextSupportModule() {
-			// See if we can find the extended mime.types from the context-support module...
-			Resource mappingLocation = new ClassPathResource("org/springframework/mail/javamail/mime.types");
-			if (mappingLocation.exists()) {
-				InputStream inputStream = null;
-				try {
-					inputStream = mappingLocation.getInputStream();
-					return new MimetypesFileTypeMap(inputStream);
-				}
-				catch (IOException ex) {
-					// ignore
-				}
-				finally {
-					if (inputStream != null) {
-						try {
-							inputStream.close();
-						}
-						catch (IOException ex) {
-							// ignore
-						}
-					}
-				}
-			}
-			return FileTypeMap.getDefaultFileTypeMap();
-		}
-
-		public static MediaType getMediaType(Resource resource) {
-			String filename = resource.getFilename();
-			if (filename != null) {
-				String mediaType = fileTypeMap.getContentType(filename);
-				if (StringUtils.hasText(mediaType)) {
-					return MediaType.parseMediaType(mediaType);
-				}
-			}
-			return null;
-		}
-	}
-
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -29,6 +29,7 @@ import org.springframework.http.HttpInputMessage;
 import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.StreamUtils;
 
@@ -41,6 +42,9 @@ import org.springframework.util.StreamUtils;
  */
 public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessageConverter<Object> {
 
+	private static final boolean jafPresent = ClassUtils.isPresent(
+			"javax.activation.FileTypeMap", ResourceHttpMessageConverter.class.getClassLoader());
+
 	public ResourceRegionHttpMessageConverter() {
 		super(MediaType.ALL);
 	}
@@ -71,6 +75,23 @@ public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessa
 		return null;
 	}
 
+	@Override
+	@SuppressWarnings("unchecked")
+	protected MediaType getDefaultContentType(Object object) {
+		if (jafPresent) {
+			if(object instanceof ResourceRegion) {
+				return ActivationMediaTypeFactory.getMediaType(((ResourceRegion) object).getResource());
+			}
+			else {
+				Collection<ResourceRegion> regions = (Collection<ResourceRegion>) object;
+				if(regions.size() > 0) {
+					return ActivationMediaTypeFactory.getMediaType(regions.iterator().next().getResource());
+				}
+			}
+		}
+		return MediaType.APPLICATION_OCTET_STREAM;
+	}
+
 	@Override
 	public boolean canWrite(Class<?> clazz, MediaType mediaType) {
 		return canWrite(clazz, null, mediaType);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -16,13 +16,17 @@
 
 package org.springframework.http.converter;
 
+import java.io.ByteArrayInputStream;
 import java.lang.reflect.Type;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import org.hamcrest.Matchers;
 import org.junit.Test;
+import org.mockito.BDDMockito;
+import org.mockito.Mockito;
 
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.io.ClassPathResource;
@@ -34,8 +38,10 @@ import org.springframework.http.MediaType;
 import org.springframework.http.MockHttpOutputMessage;
 import org.springframework.util.StringUtils;
 
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Test cases for {@link ResourceRegionHttpMessageConverter} class.
@@ -139,4 +145,21 @@ public class ResourceRegionHttpMessageConverterTests {
 		assertThat(ranges[15], is("resource content."));
 	}
 
+	@Test // SPR-15041
+	public void applicationOctetStreamDefaultContentType() throws Exception {
+		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
+		ClassPathResource body = Mockito.mock(ClassPathResource.class);
+		BDDMockito.given(body.getFilename()).willReturn("spring.dat");
+		BDDMockito.given(body.contentLength()).willReturn(12L);
+		BDDMockito.given(body.getInputStream()).willReturn(new ByteArrayInputStream("Spring Framework".getBytes()));
+		HttpRange range = HttpRange.createByteRange(0, 5);
+		ResourceRegion resourceRegion = range.toResourceRegion(body);
+
+		converter.write(Collections.singletonList(resourceRegion), null, outputMessage);
+
+		assertThat(outputMessage.getHeaders().getContentType(), is(MediaType.APPLICATION_OCTET_STREAM));
+		assertThat(outputMessage.getHeaders().getFirst(HttpHeaders.CONTENT_RANGE), is("bytes 0-5/12"));
+		assertThat(outputMessage.getBodyAsString(Charset.forName("UTF-8")), is("Spring"));
+	}
+
 }