diff --git a/spring-core/src/main/java/org/springframework/util/FileCopyUtils.java b/spring-core/src/main/java/org/springframework/util/FileCopyUtils.java
index 37fb1a960b55..73140dd80e70 100644
--- a/spring-core/src/main/java/org/springframework/util/FileCopyUtils.java
+++ b/spring-core/src/main/java/org/springframework/util/FileCopyUtils.java
@@ -108,12 +108,10 @@ public static int copy(InputStream in, OutputStream out) throws IOException {
 		Assert.notNull(in, "No InputStream specified");
 		Assert.notNull(out, "No OutputStream specified");
 
-		try {
-			return StreamUtils.copy(in, out);
-		}
-		finally {
-			close(in);
-			close(out);
+		try (in; out) {
+			int count = (int) in.transferTo(out);
+			out.flush();
+			return count;
 		}
 	}
 
diff --git a/spring-core/src/main/java/org/springframework/util/StreamUtils.java b/spring-core/src/main/java/org/springframework/util/StreamUtils.java
index f57943a29e8d..04fcd15b90e6 100644
--- a/spring-core/src/main/java/org/springframework/util/StreamUtils.java
+++ b/spring-core/src/main/java/org/springframework/util/StreamUtils.java
@@ -65,9 +65,7 @@ public static byte[] copyToByteArray(@Nullable InputStream in) throws IOExceptio
 			return new byte[0];
 		}
 
-		ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
-		copy(in, out);
-		return out.toByteArray();
+		return in.readAllBytes();
 	}
 
 	/**
diff --git a/spring-web/src/main/java/org/springframework/http/converter/ByteArrayHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/ByteArrayHttpMessageConverter.java
index 648f2406bd9d..b5be96421b46 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/ByteArrayHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/ByteArrayHttpMessageConverter.java
@@ -16,7 +16,6 @@
 
 package org.springframework.http.converter;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 
 import org.springframework.http.HttpInputMessage;
@@ -53,11 +52,7 @@ public boolean supports(Class<?> clazz) {
 
 	@Override
 	public byte[] readInternal(Class<? extends byte[]> clazz, HttpInputMessage inputMessage) throws IOException {
-		long contentLength = inputMessage.getHeaders().getContentLength();
-		ByteArrayOutputStream bos =
-				new ByteArrayOutputStream(contentLength >= 0 ? (int) contentLength : StreamUtils.BUFFER_SIZE);
-		StreamUtils.copy(inputMessage.getBody(), bos);
-		return bos.toByteArray();
+		return inputMessage.getBody().readAllBytes();
 	}
 
 	@Override
diff --git a/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
index f587aecf7ff9..0b54b1ca085e 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
@@ -19,6 +19,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.OutputStream;
 
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.InputStreamResource;
@@ -131,22 +132,13 @@ protected void writeInternal(Resource resource, HttpOutputMessage outputMessage)
 
 	protected void writeContent(Resource resource, HttpOutputMessage outputMessage)
 			throws IOException, HttpMessageNotWritableException {
-		try {
-			InputStream in = resource.getInputStream();
-			try {
-				StreamUtils.copy(in, outputMessage.getBody());
-			}
-			catch (NullPointerException ex) {
-				// ignore, see SPR-13620
-			}
-			finally {
-				try {
-					in.close();
-				}
-				catch (Throwable ex) {
-					// ignore, see SPR-12999
-				}
-			}
+		try (InputStream in = resource.getInputStream()){
+			OutputStream out = outputMessage.getBody();
+			in.transferTo(out);
+			out.flush();
+		}
+		catch (NullPointerException ex) {
+			// ignore, see SPR-13620
 		}
 		catch (FileNotFoundException ex) {
 			// ignore, see SPR-12999