87 lines
2.5 KiB
Java
87 lines
2.5 KiB
Java
/*
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* j8583 A Java implementation of the ISO8583 protocol
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* Copyright (C) 2007 Enrique Zamudio Lopez
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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package com.solab.iso8583.util;
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/** Utility class to perform HEX encoding/decoding of values.
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* @author Enrique Zamudio
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*/
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public final class HexCodec {
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static final char[] HEX = "0123456789ABCDEF".toCharArray();
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private HexCodec(){}
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public static String hexEncode(byte[] buffer, int start, int length) {
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if (buffer.length == 0) {
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return "";
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}
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int holder = 0;
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char[] chars = new char[length * 2];
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int pos = -1;
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for (int i = start; i < start+length; i++) {
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holder = (buffer[i] & 0xf0) >> 4;
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chars[++pos * 2] = HEX[holder];
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holder = buffer[i] & 0x0f;
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chars[(pos * 2) + 1] = HEX[holder];
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}
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return new String(chars);
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}
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public static byte[] hexDecode(String hex) {
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//A null string returns an empty array
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if (hex == null || hex.length() == 0) {
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return new byte[0];
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} else if (hex.length() < 3) {
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return new byte[]{ (byte)(Integer.parseInt(hex, 16) & 0xff) };
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}
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//Adjust accordingly for odd-length strings
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int count = hex.length();
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int nibble = 0;
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if (count % 2 != 0) {
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count++;
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nibble = 1;
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}
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byte[] buf = new byte[count / 2];
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char c = 0;
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int holder = 0;
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int pos = 0;
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for (int i = 0; i < buf.length; i++) {
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for (int z = 0; z < 2 && pos<hex.length(); z++) {
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c = hex.charAt(pos++);
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if (c >= 'A' && c <= 'F') {
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c -= 55;
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} else if (c >= '0' && c <= '9') {
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c -= 48;
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} else if (c >= 'a' && c <= 'f') {
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c -= 87;
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}
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if (nibble == 0) {
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holder = c << 4;
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} else {
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holder |= c;
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buf[i] = (byte)holder;
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}
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nibble = 1 - nibble;
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}
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}
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return buf;
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}
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}
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