/*
* 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.
* 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.util;
import java.io.
IOException;
import java.io.
InputStream;
import java.security.
MessageDigest;
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
*/
public abstract class
DigestUtils {
private static final
String MD5_ALGORITHM_NAME = "MD5";
private static final char[]
HEX_CHARS =
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* Calculate the MD5 digest of the given bytes.
* @param bytes the bytes to calculate the digest over
* @return the digest
*/
public static byte[]
md5Digest(byte[]
bytes) {
return
digest(
MD5_ALGORITHM_NAME,
bytes);
}
/**
* Calculate the MD5 digest of the given stream.
* @param inputStream the InputStream to calculate the digest over
* @return the digest
* @since 4.2
*/
public static byte[]
md5Digest(
InputStream inputStream) throws
IOException {
return
digest(
MD5_ALGORITHM_NAME,
inputStream);
}
/**
* 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
*/
public static
String md5DigestAsHex(byte[]
bytes) {
return
digestAsHexString(
MD5_ALGORITHM_NAME,
bytes);
}
/**
* 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
*/
public static
String md5DigestAsHex(
InputStream inputStream) throws
IOException {
return
digestAsHexString(
MD5_ALGORITHM_NAME,
inputStream);
}
/**
* Append a hexadecimal string representation of the MD5 digest of the given
* bytes to the given {@link StringBuilder}.
* @param bytes the bytes to calculate the digest over
* @param builder the string builder to append the digest to
* @return the given string builder
*/
public static
StringBuilder appendMd5DigestAsHex(byte[]
bytes,
StringBuilder builder) {
return
appendDigestAsHex(
MD5_ALGORITHM_NAME,
bytes,
builder);
}
/**
* Append a hexadecimal string representation of the MD5 digest of the given
* inputStream to the given {@link StringBuilder}.
* @param inputStream the inputStream to calculate the digest over
* @param builder the string builder to append the digest to
* @return the given string builder
* @since 4.2
*/
public static
StringBuilder appendMd5DigestAsHex(
InputStream inputStream,
StringBuilder builder) throws
IOException {
return
appendDigestAsHex(
MD5_ALGORITHM_NAME,
inputStream,
builder);
}
/**
* Create a new {@link MessageDigest} with the given algorithm.
* Necessary because {@code MessageDigest} is not thread-safe.
*/
private static
MessageDigest getDigest(
String algorithm) {
try {
return
MessageDigest.
getInstance(
algorithm);
}
catch (
NoSuchAlgorithmException ex) {
throw new
IllegalStateException("Could not find MessageDigest with algorithm \"" +
algorithm + "\"",
ex);
}
}
private static byte[]
digest(
String algorithm, byte[]
bytes) {
return
getDigest(
algorithm).
digest(
bytes);
}
private static byte[]
digest(
String algorithm,
InputStream inputStream) throws
IOException {
MessageDigest messageDigest =
getDigest(
algorithm);
if (
inputStream instanceof
UpdateMessageDigestInputStream){
((
UpdateMessageDigestInputStream)
inputStream).
updateMessageDigest(
messageDigest);
return
messageDigest.
digest();
}
else {
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();
}
}
private static
String digestAsHexString(
String algorithm, byte[]
bytes) {
char[]
hexDigest =
digestAsHexChars(
algorithm,
bytes);
return new
String(
hexDigest);
}
private static
String digestAsHexString(
String algorithm,
InputStream inputStream) throws
IOException {
char[]
hexDigest =
digestAsHexChars(
algorithm,
inputStream);
return new
String(
hexDigest);
}
private static
StringBuilder appendDigestAsHex(
String algorithm, byte[]
bytes,
StringBuilder builder) {
char[]
hexDigest =
digestAsHexChars(
algorithm,
bytes);
return
builder.
append(
hexDigest);
}
private static
StringBuilder appendDigestAsHex(
String algorithm,
InputStream inputStream,
StringBuilder builder)
throws
IOException {
char[]
hexDigest =
digestAsHexChars(
algorithm,
inputStream);
return
builder.
append(
hexDigest);
}
private static char[]
digestAsHexChars(
String algorithm, byte[]
bytes) {
byte[]
digest =
digest(
algorithm,
bytes);
return
encodeHex(
digest);
}
private static char[]
digestAsHexChars(
String algorithm,
InputStream inputStream) throws
IOException {
byte[]
digest =
digest(
algorithm,
inputStream);
return
encodeHex(
digest);
}
private static char[]
encodeHex(byte[]
bytes) {
char[]
chars = new char[32];
for (int
i = 0;
i <
chars.length;
i =
i + 2) {
byte
b =
bytes[
i / 2];
chars[
i] =
HEX_CHARS[(
b >>> 0x4) & 0xf];
chars[
i + 1] =
HEX_CHARS[
b & 0xf];
}
return
chars;
}
}