/*
* Copyright 1999-2017 Alibaba Group Holding Ltd.
*
* 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 com.alibaba.druid.util;
/**
* format validation This class encodes/decodes hexadecimal data
*
* @author Jeffrey Rodriguez
* @version $Id: HexBin.java,v 1.4 2007/07/19 04:38:32 ofung Exp $
*/
public final class HexBin {
static private final int BASE_LENGTH = 128;
static private final int LOOKUP_LENGTH = 16;
static final private byte[] HEX_NUMBER_TABLE = new byte[BASE_LENGTH];
static final private char[] UPPER_CHARS = new char[LOOKUP_LENGTH];
static final private char[] LOWER_CHARS = new char[LOOKUP_LENGTH];
static {
for (int i = 0; i < BASE_LENGTH; i++) {
HEX_NUMBER_TABLE[i] = -1;
}
for (int i = '9'; i >= '0'; i--) {
HEX_NUMBER_TABLE[i] = (byte) (i - '0');
}
for (int i = 'F'; i >= 'A'; i--) {
HEX_NUMBER_TABLE[i] = (byte) (i - 'A' + 10);
}
for (int i = 'f'; i >= 'a'; i--) {
HEX_NUMBER_TABLE[i] = (byte) (i - 'a' + 10);
}
for (int i = 0; i < 10; i++) {
UPPER_CHARS[i] = (char) ('0' + i);
LOWER_CHARS[i] = (char) ('0' + i);
}
for (int i = 10; i <= 15; i++) {
UPPER_CHARS[i] = (char) ('A' + i - 10);
LOWER_CHARS[i] = (char) ('a' + i - 10);
}
}
public static String encode(byte[] bytes) {
return encode(bytes, true);
}
public static String encode(byte[] bytes, boolean upperCase) {
if (bytes == null) {
return null;
}
final char[] chars = upperCase ? UPPER_CHARS : LOWER_CHARS;
char[] hex = new char[bytes.length * 2];
for (int i = 0; i < bytes.length; i++) {
int b = bytes[i] & 0xFF;
hex[i * 2] = chars[b >> 4];
hex[i * 2 + 1] = chars[b & 0xf];
}
return new String(hex);
}
/**
* Decode hex string to a byte array
*
* @param encoded encoded string
* @return return array of byte to encode
*/
static public byte[] decode(String encoded) {
if (encoded == null) {
return null;
}
int lengthData = encoded.length();
if (lengthData % 2 != 0) {
return null;
}
char[] binaryData = encoded.toCharArray();
int lengthDecode = lengthData / 2;
byte[] decodedData = new byte[lengthDecode];
byte temp1, temp2;
char tempChar;
for (int i = 0; i < lengthDecode; i++) {
tempChar = binaryData[i * 2];
temp1 = (tempChar < BASE_LENGTH) ? HEX_NUMBER_TABLE[tempChar] : -1;
if (temp1 == -1) {
return null;
}
tempChar = binaryData[i * 2 + 1];
temp2 = (tempChar < BASE_LENGTH) ? HEX_NUMBER_TABLE[tempChar] : -1;
if (temp2 == -1) {
return null;
}
decodedData[i] = (byte) ((temp1 << 4) | temp2);
}
return decodedData;
}
}