io.undertow.util.HexConverter Maven / Gradle / Ivy
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* 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 Darran Lofthouse
*/
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.
*
* 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.
*
* 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.
*
* 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());
}
}