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 package org.apache.tika.mime; 18 19 /** 20 * 21 * A set of Hex encoding and decoding utility methods. 22 * 23 */ 24 public class HexCoDec { 25 26 private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', 27 '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; 28 29 /** 30 * Decode a hex string 31 * 32 * @param hexValue 33 * the string of hex characters 34 * @return the decode hex string as bytes. 35 */ 36 public static byte[] decode(String hexValue) { 37 return decode(hexValue.toCharArray()); 38 } 39 40 /** 41 * Decode an array of hex chars 42 * 43 * @param hexChars 44 * an array of hex characters. 45 * @return the decode hex chars as bytes. 46 */ 47 public static byte[] decode(char[] hexChars) { 48 return decode(hexChars, 0, hexChars.length); 49 } 50 51 /** 52 * Decode an array of hex chars. 53 * 54 * @param hexChars 55 * an array of hex characters. 56 * @param startIndex 57 * the index of the first character to decode 58 * @param length 59 * the number of characters to decode. 60 * @return the decode hex chars as bytes. 61 */ 62 public static byte[] decode(char[] hexChars, int startIndex, int length) { 63 if ((length & 1) != 0) 64 throw new IllegalArgumentException("Length must be even"); 65 66 byte[] result = new byte[length / 2]; 67 for (int j = 0; j < result.length; j++) { 68 result[j] = (byte) (hexCharToNibble(hexChars[startIndex++]) * 16 + hexCharToNibble(hexChars[startIndex++])); 69 } 70 return result; 71 } 72 73 /** 74 * Hex encode an array of bytes 75 * 76 * @param bites 77 * the array of bytes to encode. 78 * @return the array of hex characters. 79 */ 80 public static char[] encode(byte[] bites) { 81 return encode(bites, 0, bites.length); 82 } 83 84 /** 85 * Hex encode an array of bytes 86 * 87 * @param bites 88 * the array of bytes to encode. 89 * @param startIndex 90 * the index of the first character to encode. 91 * @param length 92 * the number of characters to encode. 93 * @return the array of hex characters. 94 */ 95 public static char[] encode(byte[] bites, int startIndex, int length) { 96 char[] result = new char[length * 2]; 97 for (int i = 0, j = 0; i < length; i++) { 98 int bite = bites[startIndex++] & 0xff; 99 result[j++] = HEX_CHARS[bite >> 4]; 100 result[j++] = HEX_CHARS[bite & 0xf]; 101 } 102 return result; 103 } 104 105 /** 106 * Internal method to turn a hex char into a nibble. 107 */ 108 private static int hexCharToNibble(char ch) { 109 if ((ch >= '0') && (ch <= '9')) { 110 return ch - '0'; 111 } else if ((ch >= 'a') && (ch <= 'f')) { 112 return ch - 'a' + 10; 113 } else if ((ch >= 'A') && (ch <= 'F')) { 114 return ch - 'A' + 10; 115 } else { 116 throw new IllegalArgumentException("Not a hex char - '" + ch + "'"); 117 } 118 } 119 120 }