View Javadoc

1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.directory.mavibot.btree.managed;
21  
22  
23  import java.io.IOException;
24  
25  import org.apache.directory.mavibot.btree.serializer.ElementSerializer;
26  
27  
28  /**
29   * A class storing either a key, or an offset to the key on the page's byte[]
30   * 
31   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
32   * 
33   * <K> The key type
34   */
35  public class KeyHolder<K>
36  {
37      /** The deserialized key */
38      private K key;
39  
40      /** The ByteBuffer storing the key */
41      private byte[] raw;
42  
43      /** The Key serializer */
44      private ElementSerializer<K> keySerializer;
45  
46  
47      /**
48       * Create a new KeyHolder instance
49       * @param keySerializer The KeySerializer instance
50       * @param key The key to store
51       */
52      /* No Qualifier */KeyHolder( ElementSerializer<K> keySerializer, K key )
53      {
54          this.key = key;
55          this.keySerializer = keySerializer;
56          raw = keySerializer.serialize( key );
57      }
58  
59  
60      /**
61       * Create a new KeyHolder instance
62       * @param keySerializer The KeySerializer instance
63       * @param raw the bytes representing the serialized key
64       */
65      /* No Qualifier */KeyHolder( ElementSerializer<K> keySerializer, byte[] raw )
66      {
67          this.key = null;
68          this.keySerializer = keySerializer;
69          this.raw = raw;
70      }
71  
72  
73      /**
74       * @return the key
75       */
76      public K getKey()
77      {
78          if ( key == null )
79          {
80              try
81              {
82                  key = keySerializer.fromBytes( raw );
83              }
84              catch ( IOException ioe )
85              {
86                  // Nothing we can do here...
87              }
88          }
89  
90          return key;
91      }
92  
93  
94      /**
95       * @param key the Key to store in into the KeyHolder
96       */
97      public void setKey( K key )
98      {
99          this.key = key;
100         raw = keySerializer.serialize( key );
101     }
102 
103 
104     /**
105      * @return The internal serialized byte[]
106      */
107     /* No qualifier */byte[] getRaw()
108     {
109         return raw;
110     }
111 
112 
113     /**
114      * @see Object#toString()
115      */
116     public String toString()
117     {
118         StringBuilder sb = new StringBuilder();
119 
120         sb.append( "KeyHolder[" );
121 
122         if ( key != null )
123         {
124             sb.append( key );
125             sb.append( ", " );
126         }
127         else
128         {
129             sb.append( "null," );
130         }
131 
132         if ( raw != null )
133         {
134             sb.append( raw.length );
135         }
136         else
137         {
138             sb.append( "null" );
139         }
140 
141         sb.append( "]" );
142 
143         return sb.toString();
144     }
145 }