View Javadoc
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   * <b>IBAN</b> (International Bank Account Number) Check Digit calculation/validation.
23   * <p>
24   * This routine is based on the ISO 7064 Mod 97,10 check digit calculation routine.
25   * <p>
26   * The two check digit characters in a IBAN number are the third and fourth characters
27   * in the code. For <i>check digit</i> calculation/validation the first four characters are moved
28   * to the end of the code.
29   *  So <code>CCDDnnnnnnn</code> becomes <code>nnnnnnnCCDD</code> (where
30   *  <code>CC</code> is the country code and <code>DD</code> is the check digit). For
31   *  check digit calculation the check digit value should be set to zero (i.e.
32   *  <code>CC00nnnnnnn</code> in this example.
33   * <p>
34   * Note: the class does not check the format of the IBAN number, only the check digits.
35   * <p>
36   * For further information see
37   *  <a href="http://en.wikipedia.org/wiki/International_Bank_Account_Number">Wikipedia -
38   *  IBAN number</a>.
39   *
40   * @version $Revision: 1739357 $
41   * @since Validator 1.4
42   */
43  public final class IBANCheckDigit implements CheckDigit, Serializable {
44  
45      private static final int MIN_CODE_LEN = 5;
46  
47      private static final long serialVersionUID = -3600191725934382801L;
48  
49      private static final int MAX_ALPHANUMERIC_VALUE = 35; // Character.getNumericValue('Z')
50  
51      /** Singleton IBAN Number Check Digit instance */
52      public static final CheckDigit IBAN_CHECK_DIGIT = new IBANCheckDigit();
53  
54      private static final long MAX = 999999999;
55  
56      private static final long MODULUS = 97;
57  
58      /**
59       * Construct Check Digit routine for IBAN Numbers.
60       */
61      public IBANCheckDigit() {
62      }
63  
64      /**
65       * Validate the check digit of an IBAN code.
66       *
67       * @param code The code to validate
68       * @return <code>true</code> if the check digit is valid, otherwise
69       * <code>false</code>
70       */
71      @Override
72      public boolean isValid(String code) {
73          if (code == null || code.length() < MIN_CODE_LEN) {
74              return false;
75          }
76          String check = code.substring(2,4); // CHECKSTYLE IGNORE MagicNumber
77          if ("00".equals(check) || "01".equals(check) || "99".equals(check)) {
78              return false;
79          }
80          try {
81              int modulusResult = calculateModulus(code);
82              return (modulusResult == 1);
83          } catch (CheckDigitException  ex) {
84              return false;
85          }
86      }
87  
88      /**
89       * Calculate the <i>Check Digit</i> for an IBAN code.
90       * <p>
91       * <b>Note:</b> The check digit is the third and fourth
92       * characters and is set to the value "<code>00</code>".
93       *
94       * @param code The code to calculate the Check Digit for
95       * @return The calculated Check Digit as 2 numeric decimal characters, e.g. "42"
96       * @throws CheckDigitException if an error occurs calculating
97       * the check digit for the specified code
98       */
99      @Override
100     public String calculate(String code) throws CheckDigitException {
101         if (code == null || code.length() < MIN_CODE_LEN) {
102             throw new CheckDigitException("Invalid Code length=" +
103                     (code == null ? 0 : code.length()));
104         }
105         code = code.substring(0, 2) + "00" + code.substring(4); // CHECKSTYLE IGNORE MagicNumber
106         int modulusResult = calculateModulus(code);
107         int charValue = (98 - modulusResult); // CHECKSTYLE IGNORE MagicNumber
108         String checkDigit = Integer.toString(charValue);
109         return (charValue > 9 ? checkDigit : "0" + checkDigit); // CHECKSTYLE IGNORE MagicNumber
110     }
111 
112     /**
113      * Calculate the modulus for a code.
114      *
115      * @param code The code to calculate the modulus for.
116      * @return The modulus value
117      * @throws CheckDigitException if an error occurs calculating the modulus
118      * for the specified code
119      */
120     private int calculateModulus(String code) throws CheckDigitException {
121         String reformattedCode = code.substring(4) + code.substring(0, 4); // CHECKSTYLE IGNORE MagicNumber
122         long total = 0;
123         for (int i = 0; i < reformattedCode.length(); i++) {
124             int charValue = Character.getNumericValue(reformattedCode.charAt(i));
125             if (charValue < 0 || charValue > MAX_ALPHANUMERIC_VALUE) {
126                 throw new CheckDigitException("Invalid Character[" +
127                         i + "] = '" + charValue + "'");
128             }
129             total = (charValue > 9 ? total * 100 : total * 10) + charValue; // CHECKSTYLE IGNORE MagicNumber
130             if (total > MAX) {
131                 total = total % MODULUS;
132             }
133         }
134         return (int)(total % MODULUS);
135     }
136 
137 }