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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.id.serial;
18  
19  /**
20   * <code>PrefixedAlphanumericGenerator</code> is an identifier generator
21   * that generates an incrementing number in base 36 with a prefix as a String
22   * object.
23   *
24   * <p>All generated ids have the same length (prefixed and padded with 0's
25   * on the left), which is determined by the <code>size</code> parameter passed
26   * to the constructor.<p>
27   *
28   * <p>The <code>wrap</code> property determines whether or not the sequence wraps
29   * when it reaches the largest value that can be represented in <code>size</code>
30   * base 36 digits. If <code>wrap</code> is false and the the maximum representable
31   * value is exceeded, an {@link IllegalStateException} is thrown.</p>
32   *
33   * @author Commons-Id team
34   * @version $Id$
35   */
36  public class PrefixedAlphanumericGenerator extends AlphanumericGenerator {
37  
38      /** Prefix. */
39      private final String prefix;
40  
41  
42      /**
43       * Create a new prefixed alphanumeric generator with the specified prefix.
44       *
45       * @param prefix prefix, must not be null
46       * @param wrap should the factory wrap when it reaches the maximum
47       *  value that can be represented in <code>size</code> base 36 digits
48       *  (or throw an exception)
49       * @param size the size of the identifier, including prefix length
50       * @throws IllegalArgumentException if size less prefix length is not at least one
51       * @throws NullPointerException if prefix is <code>null</code>
52       */
53      public PrefixedAlphanumericGenerator(String prefix, boolean wrap, int size) {
54          super(wrap, size - ((prefix == null) ? 0 : prefix.length()));
55  
56          if (prefix == null) {
57              throw new NullPointerException("prefix must not be null");
58          }
59          if (size <= prefix.length()) {
60              throw new IllegalArgumentException("size less prefix length must be at least one");
61          }
62          this.prefix = prefix;
63      }
64  
65  
66      /**
67       * Return the prefix for this prefixed alphanumeric generator.
68       *
69       * @return the prefix for this prefixed alphanumeric generator
70       */
71      public String getPrefix() {
72          return prefix;
73      }
74  
75      public long maxLength() {
76          return super.maxLength() + prefix.length();
77      }
78  
79      public long minLength() {
80          return super.minLength() + prefix.length();
81      }
82  
83      public int getSize() {
84          return super.getSize() + prefix.length();
85      }
86  
87      public String nextStringIdentifier() {
88          StringBuffer sb = new StringBuffer(prefix);
89          sb.append(super.nextStringIdentifier());
90          return sb.toString();
91      }
92  }