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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.validator.routines.checkdigit;
18  
19  import java.io.Serializable;
20  
21  /**
22   * Combined <b>ISBN-10</b> / <b>ISBN-13</b> Check Digit calculation/validation.
23   * <p>
24   * This implementation validates/calculates ISBN check digits
25   * based on the length of the code passed to it - delegating
26   * either to the {@link ISBNCheckDigit#ISBN10_CHECK_DIGIT} or the
27   * {@link ISBNCheckDigit#ISBN13_CHECK_DIGIT} routines to perform the actual
28   * validation/calculation.
29   * <p>
30   * <b>N.B.</b> From 1st January 2007 the book industry will start to use a new 13 digit
31   * ISBN number (rather than this 10 digit ISBN number) which uses the EAN-13 / UPC
32   * standard.
33   *
34   * @version $Revision: 1739357 $
35   * @since Validator 1.4
36   */
37  public final class ISBNCheckDigit implements CheckDigit, Serializable {
38  
39      private static final long serialVersionUID = 1391849166205184558L;
40  
41      /** Singleton ISBN-10 Check Digit instance */
42      public static final CheckDigit ISBN10_CHECK_DIGIT = ISBN10CheckDigit.ISBN10_CHECK_DIGIT;
43  
44      /** Singleton ISBN-13 Check Digit instance */
45      public static final CheckDigit ISBN13_CHECK_DIGIT = EAN13CheckDigit.EAN13_CHECK_DIGIT;
46  
47      /** Singleton combined ISBN-10 / ISBN-13 Check Digit instance */
48      public static final CheckDigit ISBN_CHECK_DIGIT   = new ISBNCheckDigit();
49  
50      /**
51       * Calculate an ISBN-10 or ISBN-13 check digit, depending
52       * on the length of the code.
53       * <p>
54       * If the length of the code is 9, it is treated as an ISBN-10
55       * code or if the length of the code is 12, it is treated as an ISBN-13
56       * code.
57       *
58       * @param code The ISBN code to validate (should have a length of
59       * 9 or 12)
60       * @return The ISBN-10 check digit if the length is 9 or an ISBN-13
61       * check digit if the length is 12.
62       * @throws CheckDigitException if the code is missing, or an invalid
63       * length (i.e. not 9 or 12) or if there is an error calculating the
64       * check digit.
65       */
66      @Override
67      public String calculate(String code) throws CheckDigitException {
68          if (code == null || code.length() == 0) {
69              throw new CheckDigitException("ISBN Code is missing");
70          } else if (code.length() == 9) { // CHECKSTYLE IGNORE MagicNumber
71              return ISBN10_CHECK_DIGIT.calculate(code);
72          } else if (code.length() == 12) { // CHECKSTYLE IGNORE MagicNumber
73              return ISBN13_CHECK_DIGIT.calculate(code);
74          } else {
75              throw new CheckDigitException("Invalid ISBN Length = " + code.length());
76          }
77      }
78  
79      /**
80       * <p>Validate an ISBN-10 or ISBN-13 check digit, depending
81       * on the length of the code.</p>
82       * <p>
83       * If the length of the code is 10, it is treated as an ISBN-10
84       * code or ff the length of the code is 13, it is treated as an ISBN-13
85       * code.
86       *
87       * @param code The ISBN code to validate (should have a length of
88       * 10 or 13)
89       * @return <code>true</code> if the code has a length of 10 and is
90       * a valid ISBN-10 check digit or the code has a length of 13 and is
91       * a valid ISBN-13 check digit - otherwise <code>false</code>.
92       */
93      @Override
94      public boolean isValid(String code) {
95          if (code == null) {
96              return false;
97          } else if (code.length() == 10) { // CHECKSTYLE IGNORE MagicNumber
98              return ISBN10_CHECK_DIGIT.isValid(code);
99          } else if (code.length() == 13) { // CHECKSTYLE IGNORE MagicNumber
100             return ISBN13_CHECK_DIGIT.isValid(code);
101         } else {
102             return false;
103         }
104     }
105 
106 }