1 /* 2 * Copyright 2001-2004 The Apache Software Foundation. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package org.apache.commons.codec.binary; 18 19 import org.apache.commons.codec.BinaryDecoder; 20 import org.apache.commons.codec.BinaryEncoder; 21 import org.apache.commons.codec.DecoderException; 22 import org.apache.commons.codec.EncoderException; 23 24 /** 25 * Hex encoder and decoder. 26 * 27 * @since 1.1 28 * @author Apache Software Foundation 29 * @version $Id: Hex.java,v 1.13 2004/04/18 18:22:33 ggregory Exp $ 30 */ 31 public class Hex implements BinaryEncoder, BinaryDecoder { 32 33 /** 34 * Used building output as Hex 35 */ 36 private static final char[] DIGITS = { 37 '0', '1', '2', '3', '4', '5', '6', '7', 38 '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' 39 }; 40 41 /** 42 * Converts an array of characters representing hexidecimal values into an 43 * array of bytes of those same values. The returned array will be half the 44 * length of the passed array, as it takes two characters to represent any 45 * given byte. An exception is thrown if the passed char array has an odd 46 * number of elements. 47 * 48 * @param data An array of characters containing hexidecimal digits 49 * @return A byte array containing binary data decoded from 50 * the supplied char array. 51 * @throws DecoderException Thrown if an odd number or illegal of characters 52 * is supplied 53 */ 54 public static byte[] decodeHex(char[] data) throws DecoderException { 55 56 int len = data.length; 57 58 if ((len & 0x01) != 0) { 59 throw new DecoderException("Odd number of characters."); 60 } 61 62 byte[] out = new byte[len >> 1]; 63 64 // two characters form the hex value. 65 for (int i = 0, j = 0; j < len; i++) { 66 int f = toDigit(data[j], j) << 4; 67 j++; 68 f = f | toDigit(data[j], j); 69 j++; 70 out[i] = (byte) (f & 0xFF); 71 } 72 73 return out; 74 } 75 76 /** 77 * Converts a hexadecimal character to an integer. 78 * 79 * @param ch A character to convert to an integer digit 80 * @param index The index of the character in the source 81 * @return An integer 82 * @throws DecoderException Thrown if ch is an illegal hex character 83 */ 84 protected static int toDigit(char ch, int index) throws DecoderException { 85 int digit = Character.digit(ch, 16); 86 if (digit == -1) { 87 throw new DecoderException("Illegal hexadecimal charcter " + ch + " at index " + index); 88 } 89 return digit; 90 } 91 92 /** 93 * Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order. 94 * The returned array will be double the length of the passed array, as it takes two characters to represent any 95 * given byte. 96 * 97 * @param data 98 * a byte[] to convert to Hex characters 99 * @return A char[] containing hexidecimal characters 100 */ 101 public static char[] encodeHex(byte[] data) { 102 103 int l = data.length; 104 105 char[] out = new char[l << 1]; 106 107 // two characters form the hex value. 108 for (int i = 0, j = 0; i < l; i++) { 109 out[j++] = DIGITS[(0xF0 & data[i]) >>> 4 ]; 110 out[j++] = DIGITS[ 0x0F & data[i] ]; 111 } 112 113 return out; 114 } 115 116 /** 117 * Converts an array of character bytes representing hexidecimal values into an 118 * array of bytes of those same values. The returned array will be half the 119 * length of the passed array, as it takes two characters to represent any 120 * given byte. An exception is thrown if the passed char array has an odd 121 * number of elements. 122 * 123 * @param array An array of character bytes containing hexidecimal digits 124 * @return A byte array containing binary data decoded from 125 * the supplied byte array (representing characters). 126 * @throws DecoderException Thrown if an odd number of characters is supplied 127 * to this function 128 * @see #decodeHex(char[]) 129 */ 130 public byte[] decode(byte[] array) throws DecoderException { 131 return decodeHex(new String(array).toCharArray()); 132 } 133 134 /** 135 * Converts a String or an array of character bytes representing hexidecimal values into an 136 * array of bytes of those same values. The returned array will be half the 137 * length of the passed String or array, as it takes two characters to represent any 138 * given byte. An exception is thrown if the passed char array has an odd 139 * number of elements. 140 * 141 * @param object A String or, an array of character bytes containing hexidecimal digits 142 * @return A byte array containing binary data decoded from 143 * the supplied byte array (representing characters). 144 * @throws DecoderException Thrown if an odd number of characters is supplied 145 * to this function or the object is not a String or char[] 146 * @see #decodeHex(char[]) 147 */ 148 public Object decode(Object object) throws DecoderException { 149 try { 150 char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object; 151 return decodeHex(charArray); 152 } catch (ClassCastException e) { 153 throw new DecoderException(e.getMessage()); 154 } 155 } 156 157 /** 158 * Converts an array of bytes into an array of bytes for the characters representing the 159 * hexidecimal values of each byte in order. The returned array will be 160 * double the length of the passed array, as it takes two characters to 161 * represent any given byte. 162 * 163 * @param array a byte[] to convert to Hex characters 164 * @return A byte[] containing the bytes of the hexidecimal characters 165 * @see #encodeHex(byte[]) 166 */ 167 public byte[] encode(byte[] array) { 168 return new String(encodeHex(array)).getBytes(); 169 } 170 171 /** 172 * Converts a String or an array of bytes into an array of characters representing the 173 * hexidecimal values of each byte in order. The returned array will be 174 * double the length of the passed String or array, as it takes two characters to 175 * represent any given byte. 176 * 177 * @param object a String, or byte[] to convert to Hex characters 178 * @return A char[] containing hexidecimal characters 179 * @throws EncoderException Thrown if the given object is not a String or byte[] 180 * @see #encodeHex(byte[]) 181 */ 182 public Object encode(Object object) throws EncoderException { 183 try { 184 byte[] byteArray = object instanceof String ? ((String) object).getBytes() : (byte[]) object; 185 return encodeHex(byteArray); 186 } catch (ClassCastException e) { 187 throw new EncoderException(e.getMessage()); 188 } 189 } 190 191 } 192 193
