| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.validator.routines.checkdigit; |
| |
| /** |
| * Modulus 10 <b>ISIN</b> (International Securities Identifying Number) Check Digit calculation/validation. |
| * |
| * <p> |
| * ISIN Numbers are 12 character alphanumeric codes used |
| * to identify Securities. |
| * </p> |
| * |
| * <p> |
| * Check digit calculation uses the <i>Modulus 10 Double Add Double</i> technique |
| * with every second digit being weighted by 2. Alphabetic characters are |
| * converted to numbers by their position in the alphabet starting with A being 10. |
| * Weighted numbers greater than ten are treated as two separate numbers. |
| * </p> |
| * |
| * <p> |
| * See <a href="https://en.wikipedia.org/wiki/ISIN">Wikipedia - ISIN</a> |
| * for more details. |
| * </p> |
| * |
| * @since 1.4 |
| */ |
| public final class ISINCheckDigit extends ModulusCheckDigit { |
| |
| private static final long serialVersionUID = -1239211208101323599L; |
| |
| private static final int MAX_ALPHANUMERIC_VALUE = 35; // Character.getNumericValue('Z') |
| |
| /** Singleton ISIN Check Digit instance */ |
| public static final CheckDigit ISIN_CHECK_DIGIT = new ISINCheckDigit(); |
| |
| /** Weighting given to digits depending on their right position */ |
| private static final int[] POSITION_WEIGHT = {2, 1}; |
| |
| /** |
| * Constructs an ISIN Identifier Check Digit routine. |
| */ |
| public ISINCheckDigit() { |
| } |
| |
| /** |
| * Calculate the modulus for an ISIN code. |
| * |
| * @param code The code to calculate the modulus for. |
| * @param includesCheckDigit Whether the code includes the Check Digit or not. |
| * @return The modulus value |
| * @throws CheckDigitException if an error occurs calculating the modulus |
| * for the specified code |
| */ |
| @Override |
| protected int calculateModulus(final String code, final boolean includesCheckDigit) throws CheckDigitException { |
| final StringBuilder transformed = new StringBuilder(code.length() * 2); // CHECKSTYLE IGNORE MagicNumber |
| if (includesCheckDigit) { |
| final char checkDigit = code.charAt(code.length() - 1); // fetch the last character |
| if (!Character.isDigit(checkDigit)) { |
| throw new CheckDigitException("Invalid checkdigit[" + checkDigit + "] in " + code); |
| } |
| } |
| for (int i = 0; i < code.length(); i++) { |
| final int charValue = Character.getNumericValue(code.charAt(i)); |
| if (charValue < 0 || charValue > MAX_ALPHANUMERIC_VALUE) { |
| throw new CheckDigitException("Invalid Character[" + (i + 1) + "] = '" + charValue + "'"); |
| } |
| // this converts alphanumerics to two digits |
| // so there is no need to overload toInt() |
| transformed.append(charValue); |
| } |
| return super.calculateModulus(transformed.toString(), includesCheckDigit); |
| } |
| |
| /** |
| * <p>Calculates the <i>weighted</i> value of a character in the |
| * code at a specified position.</p> |
| * |
| * <p>For ISIN (from right to left) <b>odd</b> digits are weighted |
| * with a factor of <b>one</b> and <b>even</b> digits with a factor |
| * of <b>two</b>. Weighted values are reduced to their digital root</p> |
| * |
| * @param charValue The numeric value of the character. |
| * @param leftPos The position of the character in the code, counting from left to right |
| * @param rightPos The position of the character in the code, counting from right to left |
| * @return The weighted value of the character. |
| */ |
| @Override |
| protected int weightedValue(final int charValue, final int leftPos, final int rightPos) { |
| final int weight = POSITION_WEIGHT[rightPos % 2]; // CHECKSTYLE IGNORE MagicNumber |
| final int weightedValue = charValue * weight; |
| return ModulusCheckDigit.sumDigits(weightedValue); |
| } |
| } |