/*
* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 io.undertow.util;
/**
* A utility class for mapping between byte arrays and their hex representation and back again.
*
* @author <a href="mailto:darran.lofthouse@jboss.com">Darran Lofthouse</a>
*/
public class
HexConverter {
private static final char[]
HEX_CHARS = new char[]
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
private static final byte[]
HEX_BYTES = new byte[]
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* Take the supplied byte array and convert it to a hex encoded String.
*
* @param toBeConverted - the bytes to be converted.
* @return the hex encoded String.
*/
public static
String convertToHexString(byte[]
toBeConverted) {
if (
toBeConverted == null) {
throw new
NullPointerException("Parameter to be converted can not be null");
}
char[]
converted = new char[
toBeConverted.length * 2];
for (int
i = 0;
i <
toBeConverted.length;
i++) {
byte
b =
toBeConverted[
i];
converted[
i * 2] =
HEX_CHARS[
b >> 4 & 0x0F];
converted[
i * 2 + 1] =
HEX_CHARS[
b & 0x0F];
}
return
String.
valueOf(
converted);
}
/**
* Take the supplied byte array and convert it to to a byte array of the encoded
* hex values.
* <p>
* Each byte on the incoming array will be converted to two bytes on the return
* array.
*
* @param toBeConverted - the bytes to be encoded.
* @return the encoded byte array.
*/
public static byte[]
convertToHexBytes(byte[]
toBeConverted) {
if (
toBeConverted == null) {
throw new
NullPointerException("Parameter to be converted can not be null");
}
byte[]
converted = new byte[
toBeConverted.length * 2];
for (int
i = 0;
i <
toBeConverted.length;
i++) {
byte
b =
toBeConverted[
i];
converted[
i * 2] =
HEX_BYTES[
b >> 4 & 0x0F];
converted[
i * 2 + 1] =
HEX_BYTES[
b & 0x0F];
}
return
converted;
}
/**
* Take the incoming character of hex encoded data and convert to the raw byte values.
* <p>
* The characters in the incoming array are processed in pairs with two chars of a pair
* being converted to a single byte.
*
* @param toConvert - the hex encoded String to convert.
* @return the raw byte array.
*/
public static byte[]
convertFromHex(final char[]
toConvert) {
if (
toConvert.length % 2 != 0) {
throw new
IllegalArgumentException("The supplied character array must contain an even number of hex chars.");
}
byte[]
response = new byte[
toConvert.length / 2];
for (int
i = 0;
i <
response.length;
i++) {
int
posOne =
i * 2;
response[
i] = (byte)(
toByte(
toConvert,
posOne) << 4 |
toByte(
toConvert,
posOne+1));
}
return
response;
}
private static byte
toByte(final char[]
toConvert, final int
pos) {
int
response =
Character.
digit(
toConvert[
pos], 16);
if (
response < 0 ||
response > 15) {
throw new
IllegalArgumentException("Non-hex character '" +
toConvert[
pos] + "' at index=" +
pos);
}
return (byte)
response;
}
/**
* Take the incoming String of hex encoded data and convert to the raw byte values.
* <p>
* The characters in the incoming String are processed in pairs with two chars of a pair
* being converted to a single byte.
*
* @param toConvert - the hex encoded String to convert.
* @return the raw byte array.
*/
public static byte[]
convertFromHex(final
String toConvert) {
return
convertFromHex(
toConvert.
toCharArray());
}
public static void
main(
String[]
args) {
byte[]
toConvert = new byte[256];
for (int
i = 0;
i <
toConvert.length;
i++) {
toConvert[
i] = (byte)
i;
}
String hexValue =
convertToHexString(
toConvert);
System.
out.
println("Converted - " +
hexValue);
byte[]
convertedBack =
convertFromHex(
hexValue);
StringBuilder sb = new
StringBuilder();
for (byte
current :
convertedBack) {
sb.
append((int)
current).
append(" ");
}
System.
out.
println("Converted Back " +
sb.
toString());
}
}