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 */ 017package org.apache.commons.validator.routines.checkdigit; 018 019/** 020 * Modulus 10 <b>ISIN</b> (International Securities Identifying Number) Check Digit calculation/validation. 021 * 022 * <p> 023 * ISIN Numbers are 12 character alphanumeric codes used 024 * to identify Securities. 025 * </p> 026 * 027 * <p> 028 * Check digit calculation uses the <i>Modulus 10 Double Add Double</i> technique 029 * with every second digit being weighted by 2. Alphabetic characters are 030 * converted to numbers by their position in the alphabet starting with A being 10. 031 * Weighted numbers greater than ten are treated as two separate numbers. 032 * </p> 033 * 034 * <p> 035 * See <a href="http://en.wikipedia.org/wiki/ISIN">Wikipedia - ISIN</a> 036 * for more details. 037 * </p> 038 * 039 * @version $Revision$ 040 * @since Validator 1.4 041 */ 042public final class ISINCheckDigit extends ModulusCheckDigit { 043 044 private static final long serialVersionUID = -1239211208101323599L; 045 046 private static final int MAX_ALPHANUMERIC_VALUE = 35; // Character.getNumericValue('Z') 047 048 /** Singleton ISIN Check Digit instance */ 049 public static final CheckDigit ISIN_CHECK_DIGIT = new ISINCheckDigit(); 050 051 /** weighting given to digits depending on their right position */ 052 private static final int[] POSITION_WEIGHT = new int[] {2, 1}; 053 054 /** 055 * Construct an ISIN Indetifier Check Digit routine. 056 */ 057 public ISINCheckDigit() { 058 super(10); // CHECKSTYLE IGNORE MagicNumber 059 } 060 061 /** 062 * Calculate the modulus for an ISIN code. 063 * 064 * @param code The code to calculate the modulus for. 065 * @param includesCheckDigit Whether the code includes the Check Digit or not. 066 * @return The modulus value 067 * @throws CheckDigitException if an error occurs calculating the modulus 068 * for the specified code 069 */ 070 @Override 071 protected int calculateModulus(String code, boolean includesCheckDigit) throws CheckDigitException { 072 StringBuilder transformed = new StringBuilder(code.length() * 2); // CHECKSTYLE IGNORE MagicNumber 073 if (includesCheckDigit) { 074 char checkDigit = code.charAt(code.length()-1); // fetch the last character 075 if (!Character.isDigit(checkDigit)){ 076 throw new CheckDigitException("Invalid checkdigit["+ checkDigit+ "] in " + code); 077 } 078 } 079 for (int i = 0; i < code.length(); i++) { 080 int charValue = Character.getNumericValue(code.charAt(i)); 081 if (charValue < 0 || charValue > MAX_ALPHANUMERIC_VALUE) { 082 throw new CheckDigitException("Invalid Character[" + 083 (i + 1) + "] = '" + charValue + "'"); 084 } 085 // this converts alphanumerics to two digits 086 // so there is no need to overload toInt() 087 transformed.append(charValue); 088 } 089 return super.calculateModulus(transformed.toString(), includesCheckDigit); 090 } 091 092 /** 093 * <p>Calculates the <i>weighted</i> value of a charcter in the 094 * code at a specified position.</p> 095 * 096 * <p>For ISIN (from right to left) <b>odd</b> digits are weighted 097 * with a factor of <b>one</b> and <b>even</b> digits with a factor 098 * of <b>two</b>. Weighted values are reduced to their digital root</p> 099 * 100 * @param charValue The numeric value of the character. 101 * @param leftPos The position of the character in the code, counting from left to right 102 * @param rightPos The position of the character in the code, counting from right to left 103 * @return The weighted value of the character. 104 */ 105 @Override 106 protected int weightedValue(int charValue, int leftPos, int rightPos) { 107 int weight = POSITION_WEIGHT[rightPos % 2]; // CHECKSTYLE IGNORE MagicNumber 108 int weightedValue = charValue * weight; 109 return ModulusCheckDigit.sumDigits(weightedValue); 110 } 111}