001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.validator.routines.checkdigit; 018 019 import java.io.Serializable; 020 021 /** 022 * Modulus 11 <b>ISBN-10</b> Check Digit calculation/validation. 023 * <p> 024 * ISBN-10 Numbers are a numeric code except for the last (check) digit 025 * which can have a value of "X". 026 * <p> 027 * Check digit calculation is based on <i>modulus 11</i> with digits being weighted 028 * based by their position, from right to left with the first digit being weighted 029 * 1, the second 2 and so on. If the check digit is calculated as "10" it is converted 030 * to "X". 031 * <p> 032 * <b>N.B.</b> From 1st January 2007 the book industry will start to use a new 13 digit 033 * ISBN number (rather than this 10 digit ISBN number) which uses the EAN-13 / UPC 034 * (see {@link EAN13CheckDigit}) standard. 035 * <p> 036 * For further information see: 037 * <ul> 038 * <li><a href="http://en.wikipedia.org/wiki/ISBN">Wikipedia - International 039 * Standard Book Number (ISBN)</a>.</li> 040 * <li><a href="http://www.isbn.org/standards/home/isbn/transition.asp">ISBN-13 041 * Transition details</a>.</li> 042 * </ul> 043 * 044 * @version $Revision: 493905 $ $Date: 2007-01-08 03:11:38 +0100 (Mo, 08. Jan 2007) $ 045 * @since Validator 1.4 046 */ 047 public final class ISBN10CheckDigit extends ModulusCheckDigit implements Serializable { 048 049 /** Singleton ISBN-10 Check Digit instance */ 050 public static final CheckDigit INSTANCE = new ISBN10CheckDigit(); 051 052 /** 053 * Construct a modulus 11 Check Digit routine for ISBN-10. 054 */ 055 public ISBN10CheckDigit() { 056 super(11); 057 } 058 059 /** 060 * Calculates the <i>weighted</i> value of a charcter in the 061 * code at a specified position. 062 * 063 * <p>For ISBN-10 (from right to left) digits are weighted 064 * by their position.</p> 065 * 066 * @param charValue The numeric value of the character. 067 * @param leftPos The position of the character in the code, counting from left to right 068 * @param rightPos The positionof the character in the code, counting from right to left 069 * @return The weighted value of the character. 070 */ 071 protected int weightedValue(int charValue, int leftPos, int rightPos) { 072 return (charValue * rightPos); 073 } 074 075 /** 076 * <p>Convert a character at a specified position to an 077 * integer value.</p> 078 * 079 * <p>Character 'X' check digit converted to 10.</p> 080 * 081 * @param character The character to convert. 082 * @param leftPos The position of the character in the code, counting from left to right 083 * @param rightPos The positionof the character in the code, counting from right to left 084 * @return The integer value of the character. 085 * @throws CheckDigitException if an error occurs. 086 */ 087 protected int toInt(char character, int leftPos, int rightPos) 088 throws CheckDigitException { 089 if (rightPos == 1 && character == 'X') { 090 return 10; 091 } else { 092 return super.toInt(character, leftPos, rightPos); 093 } 094 } 095 096 /** 097 * <p>Convert an integer value to a character at a specified position.</p> 098 * 099 * <p>Value '10' for position 1 (check digit) converted to 'X'.</p> 100 * 101 * @param charValue The integer value of the character. 102 * @return The converted character. 103 * @throws CheckDigitException if an error occurs. 104 */ 105 protected String toCheckDigit(int charValue) 106 throws CheckDigitException { 107 if (charValue == 10) { 108 return "X"; 109 } else { 110 return super.toCheckDigit(charValue); 111 } 112 } 113 114 }