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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  package org.apache.myfaces.application.viewstate;
20  
21  import java.util.Map;
22  import javax.faces.context.ExternalContext;
23  import javax.faces.context.FacesContext;
24  import org.apache.myfaces.shared.renderkit.RendererUtils;
25  
26  /**
27   *
28   */
29  class CounterKeyFactory extends KeyFactory<Integer, String>
30  {
31  
32      /**
33       * Take the counter from session scope and increment
34       *
35       * @param facesContext
36       * @return
37       */
38      @Override
39      public Integer generateKey(FacesContext facesContext)
40      {
41          ExternalContext externalContext = facesContext.getExternalContext();
42          Object sessionObj = externalContext.getSession(true);
43          Integer sequence = null;
44          // synchronized to increase sequence if multiple requests
45          // are handled at the same time for the session
46          synchronized (sessionObj) 
47          {
48              Map<String, Object> map = externalContext.getSessionMap();
49              sequence = (Integer) map.get(RendererUtils.SEQUENCE_PARAM);
50              if (sequence == null || sequence.intValue() == Integer.MAX_VALUE)
51              {
52                  sequence = Integer.valueOf(1);
53              }
54              else
55              {
56                  sequence = Integer.valueOf(sequence.intValue() + 1);
57              }
58              map.put(RendererUtils.SEQUENCE_PARAM, sequence);
59          }
60          return sequence;
61      }
62  
63      public String encode(Integer sequence)
64      {
65          return Integer.toString(sequence, Character.MAX_RADIX);
66      }
67  
68      public Integer decode(String serverStateId)
69      {
70          return Integer.valueOf((String) serverStateId, Character.MAX_RADIX);
71      }
72  
73  }