Disable streaming when reading to Resources in RestTemplate

Prior to this commit, the `ResourceHttpMessageConverter` would support
converting from an `HttpInputMessage` to a `InputStreamResource`. This
is valid when reading resources on the server side, but it's not
compatible with the way `RestTemplate` works.

The API exposed by `RestOperations` imply that the HTTP server response
should be fully consumed and properly closed by the time the `exchange`
method returns. In other words, this HTTP client does not support
streaming the HTTP response.

This commit allows the `ResourceHttpMessageConverter` to be configured
to disable read streaming when used in `RestTemplate`.

Issue: SPR-14882

Author: bclozel

spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.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.
@@ -49,9 +49,27 @@ public class ResourceHttpMessageConverter extends AbstractHttpMessageConverter<R
 	private static final boolean jafPresent = ClassUtils.isPresent(
 			"javax.activation.FileTypeMap", ResourceHttpMessageConverter.class.getClassLoader());
 
+	private final boolean supportsReadStreaming;
 
+	/**
+	 * Create a new instance of the {@code ResourceHttpMessageConverter}
+	 * that supports read streaming, i.e. can convert an
+	 * {@code HttpInputMessage} to {@code InputStreamResource}.
+	 */
 	public ResourceHttpMessageConverter() {
 		super(MediaType.ALL);
+		this.supportsReadStreaming = true;
+	}
+
+	/**
+	 * Create a new instance of the {@code ResourceHttpMessageConverter}
+	 * @param supportsReadStreaming whether the converter should support
+	 * read streaming, i.e. convert to {@code InputStreamResource}.
+	 * @since 5.0
+	 */
+	public ResourceHttpMessageConverter(boolean supportsReadStreaming) {
+		super(MediaType.ALL);
+		this.supportsReadStreaming = supportsReadStreaming;
 	}
 
 
@@ -64,7 +82,7 @@ protected boolean supports(Class<?> clazz) {
 	protected Resource readInternal(Class<? extends Resource> clazz, HttpInputMessage inputMessage)
 			throws IOException, HttpMessageNotReadableException {
 
-		if (InputStreamResource.class == clazz) {
+		if (supportsReadStreaming && InputStreamResource.class == clazz) {
 			return new InputStreamResource(inputMessage.getBody());
 		}
 		else if (clazz.isAssignableFrom(ByteArrayResource.class)) {

spring-web/src/main/java/org/springframework/web/client/RestTemplate.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.
@@ -161,7 +161,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	public RestTemplate() {
 		this.messageConverters.add(new ByteArrayHttpMessageConverter());
 		this.messageConverters.add(new StringHttpMessageConverter());
-		this.messageConverters.add(new ResourceHttpMessageConverter());
+		this.messageConverters.add(new ResourceHttpMessageConverter(false));
 		this.messageConverters.add(new SourceHttpMessageConverter<>());
 		this.messageConverters.add(new AllEncompassingFormHttpMessageConverter());
 

spring-web/src/test/java/org/springframework/http/converter/ResourceHttpMessageConverterTests.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.
@@ -21,7 +21,9 @@
 import java.io.InputStream;
 import java.util.Arrays;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
@@ -47,6 +49,9 @@ public class ResourceHttpMessageConverterTests {
 
 	private final ResourceHttpMessageConverter converter = new ResourceHttpMessageConverter();
 
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
 
 	@Test
 	public void canReadResource() {
@@ -79,6 +84,17 @@ public void shouldReadInputStreamResource() throws IOException {
 		}
 	}
 
+	@Test  // SPR-14882
+	public void shouldNotReadInputStreamResource() throws IOException {
+		ResourceHttpMessageConverter noStreamConverter = new ResourceHttpMessageConverter(false);
+		try (InputStream body = getClass().getResourceAsStream("logo.jpg") ) {
+			this.thrown.expect(IllegalStateException.class);
+			MockHttpInputMessage inputMessage = new MockHttpInputMessage(body);
+			inputMessage.getHeaders().setContentType(MediaType.IMAGE_JPEG);
+			noStreamConverter.read(InputStreamResource.class, inputMessage);
+		}
+	}
+
 	@Test
 	public void shouldWriteImageResource() throws IOException {
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();