DigestUtils processes InputStream with buffered read instead of full copy

Issue: SPR-14427

spring-core/src/main/java/org/springframework/util/DigestUtils.java

@@ -23,11 +23,13 @@ import java.security.NoSuchAlgorithmException;
 
 /**
  * Miscellaneous methods for calculating digests.
+ *
  * <p>Mainly for internal use within the framework; consider
  * <a href="http://commons.apache.org/codec/">Apache Commons Codec</a>
  * for a more comprehensive suite of digest utilities.
  *
  * @author Arjen Poutsma
+ * @author Juergen Hoeller
  * @author Craig Andrews
  * @since 3.0
  */
@@ -49,8 +51,8 @@ public abstract class DigestUtils {
 	}
 
 	/**
-	 * Calculate the MD5 digest of the given InputStream.
-	 * @param inputStream the inputStream to calculate the digest over
+	 * Calculate the MD5 digest of the given stream.
+	 * @param inputStream the InputStream to calculate the digest over
 	 * @return the digest
 	 * @since 4.2
 	 */
@@ -59,8 +61,7 @@ public abstract class DigestUtils {
 	}
 
 	/**
-	 * Return a hexadecimal string representation of the MD5 digest of the given
-	 * bytes.
+	 * Return a hexadecimal string representation of the MD5 digest of the given bytes.
 	 * @param bytes the bytes to calculate the digest over
 	 * @return a hexadecimal digest string
 	 */
@@ -69,9 +70,8 @@ public abstract class DigestUtils {
 	}
 
 	/**
-	 * Return a hexadecimal string representation of the MD5 digest of the given
-	 * inputStream.
-	 * @param inputStream the inputStream to calculate the digest over
+	 * Return a hexadecimal string representation of the MD5 digest of the given stream.
+	 * @param inputStream the InputStream to calculate the digest over
 	 * @return a hexadecimal digest string
 	 * @since 4.2
 	 */
@@ -127,7 +127,12 @@ public abstract class DigestUtils {
 			return messageDigest.digest();
 		}
 		else {
-			return messageDigest.digest(StreamUtils.copyToByteArray(inputStream));
+			final byte[] buffer = new byte[StreamUtils.BUFFER_SIZE];
+			int bytesRead = -1;
+			while ((bytesRead = inputStream.read(buffer)) != -1) {
+				messageDigest.update(buffer, 0, bytesRead);
+			}
+			return messageDigest.digest();
 		}
 	}
 

spring-core/src/test/java/org/springframework/util/DigestUtilsTests.java

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.util;
 
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 
 import org.junit.Before;
@@ -25,6 +27,7 @@ import static org.junit.Assert.*;
 
 /**
  * @author Arjen Poutsma
+ * @author Juergen Hoeller
  */
 public class DigestUtilsTests {
 
@@ -38,24 +41,39 @@ public class DigestUtilsTests {
 
 
 	@Test
-	public void md5() {
-		byte[] result = DigestUtils.md5Digest(bytes);
+	public void md5() throws IOException {
 		byte[] expected = new byte[]
 				{-0x4f, 0xa, -0x73, -0x4f, 0x64, -0x20, 0x75, 0x41, 0x5, -0x49, -0x57, -0x65, -0x19, 0x2e, 0x3f, -0x1b};
+
+		byte[] result = DigestUtils.md5Digest(bytes);
+		assertArrayEquals("Invalid hash", expected, result);
+
+		result = DigestUtils.md5Digest(new ByteArrayInputStream(bytes));
 		assertArrayEquals("Invalid hash", expected, result);
 	}
 
 	@Test
-	public void md5Hex() throws UnsupportedEncodingException {
+	public void md5Hex() throws IOException {
+		String expected = "b10a8db164e0754105b7a99be72e3fe5";
+
 		String hash = DigestUtils.md5DigestAsHex(bytes);
-		assertEquals("Invalid hash", "b10a8db164e0754105b7a99be72e3fe5", hash);
+		assertEquals("Invalid hash", expected, hash);
+
+		hash = DigestUtils.md5DigestAsHex(new ByteArrayInputStream(bytes));
+		assertEquals("Invalid hash", expected, hash);
 	}
 
 	@Test
-	public void md5StringBuilder() throws UnsupportedEncodingException {
+	public void md5StringBuilder() throws IOException {
+		String expected = "b10a8db164e0754105b7a99be72e3fe5";
+
 		StringBuilder builder = new StringBuilder();
 		DigestUtils.appendMd5DigestAsHex(bytes, builder);
-		assertEquals("Invalid hash", "b10a8db164e0754105b7a99be72e3fe5", builder.toString());
+		assertEquals("Invalid hash", expected, builder.toString());
+
+		builder = new StringBuilder();
+		DigestUtils.appendMd5DigestAsHex(new ByteArrayInputStream(bytes), builder);
+		assertEquals("Invalid hash", expected, builder.toString());
 	}
 
 }