Mega Code Archive
Decode hex string to a byte array
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/**
* format validation
*
* This class encodes/decodes hexadecimal data
*
* @xerces.internal
*
* @author Jeffrey Rodriguez
* @version $Id: HexBin.java 446747 2006-09-15 21:46:20Z mrglavas $
*/
public final class HexBin {
static private final int BASELENGTH = 128;
static private final int LOOKUPLENGTH = 16;
static final private byte [] hexNumberTable = new byte[BASELENGTH];
static final private char [] lookUpHexAlphabet = new char[LOOKUPLENGTH];
static {
for (int i = 0; i < BASELENGTH; i++ ) {
hexNumberTable[i] = -1;
}
for ( int i = '9'; i >= '0'; i--) {
hexNumberTable[i] = (byte) (i-'0');
}
for ( int i = 'F'; i>= 'A'; i--) {
hexNumberTable[i] = (byte) ( i-'A' + 10 );
}
for ( int i = 'f'; i>= 'a'; i--) {
hexNumberTable[i] = (byte) ( i-'a' + 10 );
}
for(int i = 0; i<10; i++ ) {
lookUpHexAlphabet[i] = (char)('0'+i);
}
for(int i = 10; i<=15; i++ ) {
lookUpHexAlphabet[i] = (char)('A'+i -10);
}
}
/**
* 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 < BASELENGTH) ? hexNumberTable[tempChar] : -1;
if (temp1 == -1)
return null;
tempChar = binaryData[i*2+1];
temp2 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
if (temp2 == -1)
return null;
decodedData[i] = (byte)((temp1 << 4) | temp2);
}
return decodedData;
}
}
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