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     * 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} or the
027     * {@link ISBNCheckDigit#ISBN13} 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     * @version $Revision: 493905 $ $Date: 2007-01-08 03:11:38 +0100 (Mo, 08. Jan 2007) $
035     * @since Validator 1.4
036     */
037    public final class ISBNCheckDigit implements CheckDigit, Serializable {
038    
039        /** Singleton ISBN-10 Check Digit instance */
040        public static final CheckDigit ISBN10 = ISBN10CheckDigit.INSTANCE;
041    
042        /** Singleton ISBN-13 Check Digit instance */
043        public static final CheckDigit ISBN13 = EAN13CheckDigit.INSTANCE;
044    
045        /** Singleton combined ISBN-10 / ISBN-13 Check Digit instance */
046        public static final CheckDigit ISBN   = new ISBNCheckDigit();
047    
048        /**
049         * Calculate an ISBN-10 or ISBN-13 check digit, depending
050         * on the length of the code.
051         * <p>
052         * If the length of the code is 9, it is treated as an ISBN-10
053         * code or if the length of the code is 12, it is treated as an ISBN-13
054         * code.
055         *
056         * @param code The ISBN code to validate (should have a length of
057         * 9 or 12)
058         * @return The ISBN-10 check digit if the length is 9 or an ISBN-13
059         * check digit if the length is 12.
060         * @throws CheckDigitException if the code is missing, or an invalid
061         * length (i.e. not 9 or 12) or if there is an error calculating the
062         * check digit.
063         */
064        public String calculate(String code) throws CheckDigitException {
065            if (code == null || code.length() == 0) {
066                throw new CheckDigitException("ISBN Code is missing");
067            } else if (code.length() == 9) {
068                return ISBN10.calculate(code);
069            } else if (code.length() == 12) {
070                return ISBN13.calculate(code);
071            } else {
072                throw new CheckDigitException("Invalid ISBN Length = " + code.length());
073            }
074        }
075    
076        /**
077         * <p>Validate an ISBN-10 or ISBN-13 check digit, depending
078         * on the length of the code.</p>
079         * <p>
080         * If the length of the code is 10, it is treated as an ISBN-10
081         * code or ff the length of the code is 13, it is treated as an ISBN-13
082         * code.
083         *
084         * @param code The ISBN code to validate (should have a length of
085         * 10 or 13)
086         * @return <code>true</code> if the code has a length of 10 and is
087         * a valid ISBN-10 check digit or the code has a length of 13 and is
088         * a valid ISBN-13 check digit - otherwise <code>false</code>.
089         */
090        public boolean isValid(String code) {
091            if (code == null) {
092                return false;
093            } else if (code.length() == 10) {
094                return ISBN10.isValid(code);
095            } else if (code.length() == 13) {
096                return ISBN13.isValid(code);
097            } else {
098                return false;
099            }
100        }
101    
102    }