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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;
20  
21  import javax.faces.context.FacesContext;
22  
23  /**
24   * This class provides and interface to separate the state caching operations (saving/restoring)
25   * from the renderkit specific stuff that HtmlResponseStateManager should do.
26   * 
27   * @author Leonardo Uribe
28   *
29   */
30  public abstract class StateCache<K, V>
31  {
32  
33      /**
34       * Put the state on the cache, to can be restored later.
35       * 
36       * @param facesContext
37       * @param serializedView
38       */
39      public abstract K saveSerializedView(FacesContext facesContext, V serializedView);
40      
41      /**
42       * Get the state from the cache is server side state saving is used,
43       * or decode it from the passed viewState param if client side is used.
44       * 
45       * @param facesContext
46       * @param viewId The viewId of the view to be restored
47       * @param viewState A token usually retrieved from a call to ResponseStateManager.getState that will be
48       *                  used to identify or restore the state.
49       * @return
50       */
51      public abstract V restoreSerializedView(FacesContext facesContext, String viewId, K viewState);
52  
53      /**
54       * Calculate the token to be used if server side state saving, or encode the view and return the
55       * viewState that can be used by the underlying ResponseStateManager to write the state.
56       * 
57       * @param facesContext
58       * @param state The state that will be used to derive the token returned.
59       * @return A token (usually encoded on javax.faces.ViewState input hidden field) that will be passed to 
60       *         ResponseStateManager.writeState or ResponseStateManager.getViewState to be 
61       *         output to the client.
62       */
63      public abstract K encodeSerializedState(FacesContext facesContext, Object serializedView);
64      
65      /**
66       * Indicates if the call to ResponseStateManager.writeState should be done after the view is fully rendered.
67       * Usually this is required for client side state saving, but it is not for server side state saving, because
68       * ResponseStateManager.writeState could render a just a marker and then StateManager.saveState could be called,
69       * preventing use an additional buffer. 
70       * 
71       * @param facesContext
72       * @return
73       */
74      public abstract boolean isWriteStateAfterRenderViewRequired(FacesContext facesContext);
75  }