ResourceHttpMessageConverter does not call contentLength() on InputStreamResource

Issue: SPR-12017

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -18,12 +18,12 @@ 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.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.InputStreamResource;
 import org.springframework.core.io.Resource;
 import org.springframework.http.HttpInputMessage;
 import org.springframework.http.HttpOutputMessage;
@@ -78,7 +78,9 @@ public class ResourceHttpMessageConverter extends AbstractHttpMessageConverter<R
 
 	@Override
 	protected Long getContentLength(Resource resource, MediaType contentType) throws IOException {
-		return resource.contentLength();
+		// Don't try to determine contentLength on InputStreamResource - cannot be read afterwards...
+		// Note: custom InputStreamResource subclasses could provide a pre-calculated content length!
+		return (InputStreamResource.class.equals(resource.getClass()) ? null : resource.contentLength());
 	}
 
 	@Override