1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.id;
19
20 import org.apache.commons.id.DecoderException;
21 import org.apache.commons.id.EncoderException;
22
23 /**
24 * Hex encoder and decoder.
25 *
26 * @since 1.1
27 * @author Apache Software Foundation
28 * @version $Id: Hex.java 480488 2006-11-29 08:57:26Z bayard $
29 */
30 public class Hex {//implements BinaryEncoder, BinaryDecoder {
31
32 /**
33 * Used to build output as Hex
34 */
35 private static final char[] DIGITS = {
36 '0', '1', '2', '3', '4', '5', '6', '7',
37 '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
38 };
39
40 /**
41 * Converts an array of characters representing hexidecimal values into an
42 * array of bytes of those same values. The returned array will be half the
43 * length of the passed array, as it takes two characters to represent any
44 * given byte. An exception is thrown if the passed char array has an odd
45 * number of elements.
46 *
47 * @param data An array of characters containing hexidecimal digits
48 * @return A byte array containing binary data decoded from
49 * the supplied char array.
50 * @throws DecoderException Thrown if an odd number or illegal of characters
51 * is supplied
52 */
53 public static byte[] decodeHex(char[] data) throws DecoderException {
54
55 int len = data.length;
56
57 if ((len & 0x01) != 0) {
58 throw new DecoderException("Odd number of characters.");
59 }
60
61 byte[] out = new byte[len >> 1];
62
63 // two characters form the hex value.
64 for (int i = 0, j = 0; j < len; i++) {
65 int f = toDigit(data[j], j) << 4;
66 j++;
67 f = f | toDigit(data[j], j);
68 j++;
69 out[i] = (byte) (f & 0xFF);
70 }
71
72 return out;
73 }
74
75 /**
76 * Converts a hexadecimal character to an integer.
77 *
78 * @param ch A character to convert to an integer digit
79 * @param index The index of the character in the source
80 * @return An integer
81 * @throws DecoderException Thrown if ch is an illegal hex character
82 */
83 protected static int toDigit(char ch, int index) throws DecoderException {
84 int digit = Character.digit(ch, 16);
85 if (digit == -1) {
86 throw new DecoderException("Illegal hexadecimal charcter " + ch + " at index " + index);
87 }
88 return digit;
89 }
90
91 /**
92 * Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
93 * The returned array will be double the length of the passed array, as it takes two characters to represent any
94 * given byte.
95 *
96 * @param data
97 * a byte[] to convert to Hex characters
98 * @return A char[] containing hexidecimal characters
99 */
100 public static char[] encodeHex(byte[] data) {
101
102 int l = data.length;
103
104 char[] out = new char[l << 1];
105
106 // two characters form the hex value.
107 for (int i = 0, j = 0; i < l; i++) {
108 out[j++] = DIGITS[(0xF0 & data[i]) >>> 4 ];
109 out[j++] = DIGITS[ 0x0F & data[i] ];
110 }
111
112 return out;
113 }
114
115 /**
116 * Converts an array of character bytes representing hexidecimal values into an
117 * array of bytes of those same values. The returned array will be half the
118 * length of the passed array, as it takes two characters to represent any
119 * given byte. An exception is thrown if the passed char array has an odd
120 * number of elements.
121 *
122 * @param array An array of character bytes containing hexidecimal digits
123 * @return A byte array containing binary data decoded from
124 * the supplied byte array (representing characters).
125 * @throws DecoderException Thrown if an odd number of characters is supplied
126 * to this function
127 * @see #decodeHex(char[])
128 */
129 public byte[] decode(byte[] array) throws DecoderException {
130 return decodeHex(new String(array).toCharArray());
131 }
132
133 /**
134 * Converts a String or an array of character bytes representing hexidecimal values into an
135 * array of bytes of those same values. The returned array will be half the
136 * length of the passed String or array, as it takes two characters to represent any
137 * given byte. An exception is thrown if the passed char array has an odd
138 * number of elements.
139 *
140 * @param object A String or, an array of character bytes containing hexidecimal digits
141 * @return A byte array containing binary data decoded from
142 * the supplied byte array (representing characters).
143 * @throws DecoderException Thrown if an odd number of characters is supplied
144 * to this function or the object is not a String or char[]
145 * @see #decodeHex(char[])
146 */
147 public Object decode(Object object) throws DecoderException {
148 try {
149 char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object;
150 return decodeHex(charArray);
151 } catch (ClassCastException e) {
152 throw new DecoderException(e.getMessage());
153 }
154 }
155
156 /**
157 * Converts an array of bytes into an array of bytes for the characters representing the
158 * hexidecimal values of each byte in order. The returned array will be
159 * double the length of the passed array, as it takes two characters to
160 * represent any given byte.
161 *
162 * @param array a byte[] to convert to Hex characters
163 * @return A byte[] containing the bytes of the hexidecimal characters
164 * @see #encodeHex(byte[])
165 */
166 public byte[] encode(byte[] array) {
167 return new String(encodeHex(array)).getBytes();
168 }
169
170 /**
171 * Converts a String or an array of bytes into an array of characters representing the
172 * hexidecimal values of each byte in order. The returned array will be
173 * double the length of the passed String or array, as it takes two characters to
174 * represent any given byte.
175 *
176 * @param object a String, or byte[] to convert to Hex characters
177 * @return A char[] containing hexidecimal characters
178 * @throws EncoderException Thrown if the given object is not a String or byte[]
179 * @see #encodeHex(byte[])
180 */
181 public Object encode(Object object) throws EncoderException {
182 try {
183 byte[] byteArray = object instanceof String ? ((String) object).getBytes() : (byte[]) object;
184 return encodeHex(byteArray);
185 } catch (ClassCastException e) {
186 throw new EncoderException(e.getMessage());
187 }
188 }
189
190 }
191