    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 *      https://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
    021import org.apache.commons.validator.GenericValidator;
    022
    023/**
    024 * Combined <strong>ISBN-10</strong> / <strong>ISBN-13</strong> Check Digit calculation/validation.
    025 * <p>
    026 * This implementation validates/calculates ISBN check digits
    027 * based on the length of the code passed to it - delegating
    028 * either to the {@link ISBNCheckDigit#ISBN10_CHECK_DIGIT} or the
    029 * {@link ISBNCheckDigit#ISBN13_CHECK_DIGIT} routines to perform the actual
    030 * validation/calculation.
    031 * <p>
    032 * <strong>N.B.</strong> 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 * standard.
    035 *
    036 * @since 1.4
    037 */
    038public final class ISBNCheckDigit extends AbstractCheckDigit implements Serializable {
    039
    040    private static final long serialVersionUID = 1391849166205184558L;
    041
    042    /** Singleton ISBN-10 Check Digit instance */
    043    public static final CheckDigit ISBN10_CHECK_DIGIT = ISBN10CheckDigit.ISBN10_CHECK_DIGIT;
    044
    045    /** Singleton ISBN-13 Check Digit instance */
    046    public static final CheckDigit ISBN13_CHECK_DIGIT = EAN13CheckDigit.EAN13_CHECK_DIGIT;
    047
    048    /** Singleton combined ISBN-10 / ISBN-13 Check Digit instance */
    049    public static final CheckDigit ISBN_CHECK_DIGIT = new ISBNCheckDigit();
    050
    051    /**
    052     * Constructs a new instance.
    053     */
    054    public ISBNCheckDigit() {
    055        // empty
    056    }
    057
    058    /**
    059     * Calculate an ISBN-10 or ISBN-13 check digit, depending
    060     * on the length of the code.
    061     * <p>
    062     * If the length of the code is 9, it is treated as an ISBN-10
    063     * code or if the length of the code is 12, it is treated as an ISBN-13
    064     * code.
    065     *
    066     * @param code The ISBN code to validate (should have a length of
    067     * 9 or 12)
    068     * @return The ISBN-10 check digit if the length is 9 or an ISBN-13
    069     * check digit if the length is 12.
    070     * @throws CheckDigitException if the code is missing, or an invalid
    071     * length (that is, not 9 or 12) or if there is an error calculating the
    072     * check digit.
    073     */
    074    @Override
    075    public String calculate(final String code) throws CheckDigitException {
    076        if (GenericValidator.isBlankOrNull(code)) {
    077            throw new CheckDigitException("ISBN Code is missing");
    078        }
    079        if (code.length() == 9) { // CHECKSTYLE IGNORE MagicNumber
    080            return ISBN10_CHECK_DIGIT.calculate(code);
    081        }
    082        if (code.length() == 12) { // CHECKSTYLE IGNORE MagicNumber
    083            return ISBN13_CHECK_DIGIT.calculate(code);
    084        }
    085        throw new CheckDigitException("Invalid ISBN Length = " + code.length());
    086    }
    087
    088    /**
    089     * <p>Validate an ISBN-10 or ISBN-13 check digit, depending
    090     * on the length of the code.</p>
    091     * <p>
    092     * If the length of the code is 10, it is treated as an ISBN-10
    093     * code or ff the length of the code is 13, it is treated as an ISBN-13
    094     * code.
    095     *
    096     * @param code The ISBN code to validate (should have a length of
    097     * 10 or 13)
    098     * @return {@code true} if the code has a length of 10 and is
    099     * a valid ISBN-10 check digit or the code has a length of 13 and is
    100     * a valid ISBN-13 check digit - otherwise {@code false}.
    101     */
    102    @Override
    103    public boolean isValid(final String code) {
    104        if (code == null) {
    105            return false;
    106        }
    107        if (code.length() == 10) { // CHECKSTYLE IGNORE MagicNumber
    108            return ISBN10_CHECK_DIGIT.isValid(code);
    109        }
    110        if (code.length() == 13) { // CHECKSTYLE IGNORE MagicNumber
    111            return ISBN13_CHECK_DIGIT.isValid(code);
    112        }
    113        return false;
    114    }
    115
    116}