    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
    019import java.io.Serializable;
    020
    021/**
    022 * Combined <b>ISBN-10</b> / <b>ISBN-13</b> Check Digit calculation/validation.
    023 * <p>
    024 * This implementation validates/calculates ISBN check digits
    025 * based on the length of the code passed to it - delegating
    026 * either to the {@link ISBNCheckDigit#ISBN10_CHECK_DIGIT} or the
    027 * {@link ISBNCheckDigit#ISBN13_CHECK_DIGIT} routines to perform the actual
    028 * validation/calculation.
    029 * <p>
    030 * <b>N.B.</b> From 1st January 2007 the book industry will start to use a new 13 digit
    031 * ISBN number (rather than this 10 digit ISBN number) which uses the EAN-13 / UPC
    032 * standard.
    033 *
    034 * @since 1.4
    035 */
    036public final class ISBNCheckDigit implements CheckDigit, Serializable {
    037
    038    private static final long serialVersionUID = 1391849166205184558L;
    039
    040    /** Singleton ISBN-10 Check Digit instance */
    041    public static final CheckDigit ISBN10_CHECK_DIGIT = ISBN10CheckDigit.ISBN10_CHECK_DIGIT;
    042
    043    /** Singleton ISBN-13 Check Digit instance */
    044    public static final CheckDigit ISBN13_CHECK_DIGIT = EAN13CheckDigit.EAN13_CHECK_DIGIT;
    045
    046    /** Singleton combined ISBN-10 / ISBN-13 Check Digit instance */
    047    public static final CheckDigit ISBN_CHECK_DIGIT = new ISBNCheckDigit();
    048
    049    /**
    050     * Calculate an ISBN-10 or ISBN-13 check digit, depending
    051     * on the length of the code.
    052     * <p>
    053     * If the length of the code is 9, it is treated as an ISBN-10
    054     * code or if the length of the code is 12, it is treated as an ISBN-13
    055     * code.
    056     *
    057     * @param code The ISBN code to validate (should have a length of
    058     * 9 or 12)
    059     * @return The ISBN-10 check digit if the length is 9 or an ISBN-13
    060     * check digit if the length is 12.
    061     * @throws CheckDigitException if the code is missing, or an invalid
    062     * length (i.e. not 9 or 12) or if there is an error calculating the
    063     * check digit.
    064     */
    065    @Override
    066    public String calculate(final String code) throws CheckDigitException {
    067        if (code == null || code.isEmpty()) {
    068            throw new CheckDigitException("ISBN Code is missing");
    069        }
    070        if (code.length() == 9) { // CHECKSTYLE IGNORE MagicNumber
    071            return ISBN10_CHECK_DIGIT.calculate(code);
    072        }
    073        if (code.length() == 12) { // CHECKSTYLE IGNORE MagicNumber
    074            return ISBN13_CHECK_DIGIT.calculate(code);
    075        }
    076        throw new CheckDigitException("Invalid ISBN Length = " + code.length());
    077    }
    078
    079    /**
    080     * <p>Validate an ISBN-10 or ISBN-13 check digit, depending
    081     * on the length of the code.</p>
    082     * <p>
    083     * If the length of the code is 10, it is treated as an ISBN-10
    084     * code or ff the length of the code is 13, it is treated as an ISBN-13
    085     * code.
    086     *
    087     * @param code The ISBN code to validate (should have a length of
    088     * 10 or 13)
    089     * @return {@code true} if the code has a length of 10 and is
    090     * a valid ISBN-10 check digit or the code has a length of 13 and is
    091     * a valid ISBN-13 check digit - otherwise {@code false}.
    092     */
    093    @Override
    094    public boolean isValid(final String code) {
    095        if (code == null) {
    096            return false;
    097        }
    098        if (code.length() == 10) { // CHECKSTYLE IGNORE MagicNumber
    099            return ISBN10_CHECK_DIGIT.isValid(code);
    100        }
    101        if (code.length() == 13) { // CHECKSTYLE IGNORE MagicNumber
    102            return ISBN13_CHECK_DIGIT.isValid(code);
    103        }
    104        return false;
    105    }
    106
    107}