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1   /*
2    * Copyright (c) 1998, 2005 Gargoyle Software Inc. All rights reserved.
3    *
4    * Redistribution and use in source and binary forms, with or without
5    * modification, are permitted provided that the following conditions are met:
6    *
7    * 1. Redistributions of source code must retain the above copyright notice,
8    *    this list of conditions and the following disclaimer.
9    * 2. Redistributions in binary form must reproduce the above copyright notice,
10   *    this list of conditions and the following disclaimer in the documentation
11   *    and/or other materials provided with the distribution.
12   * 3. The end-user documentation included with the redistribution, if any, must
13   *    include the following acknowledgment:
14   *
15   *       "This product includes software developed by Gargoyle Software Inc.
16   *        (http://www.GargoyleSoftware.com/)."
17   *
18   *    Alternately, this acknowledgment may appear in the software itself, if
19   *    and wherever such third-party acknowledgments normally appear.
20   * 4. The name "Gargoyle Software" must not be used to endorse or promote
21   *    products derived from this software without prior written permission.
22   *    For written permission, please contact info@GargoyleSoftware.com.
23   * 5. Products derived from this software may not be called "GSBase", nor may
24   *    "GSBase" appear in their name, without prior written permission of
25   *    Gargoyle Software Inc.
26   *
27   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
28   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
29   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GARGOYLE
30   * SOFTWARE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
31   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
33   * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
36   * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   */
38  package com.gargoylesoftware.base.objectstore;
39  
40  import java.util.Collections;
41  import java.util.Map;
42  
43  /***
44   * An object store that just dispatches commands to other object stores
45   *
46   * @version $Revision: 1.6 $
47   * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
48   */
49  public class DispatchingObjectStore extends ObjectStore {
50  
51      private final Map dispatchMap_;
52      private final Map resourceFactoryMap_;
53  
54  
55      /***
56       * Create an instance.  If you use this constructor then you must
57       * override findStoreClass() since the dispatchMap has not been populated
58       *
59       * @param nameToResourceFactoryMap keys are names, values are the
60       * resource factory objects that are represented by the name.  This map
61       * will be passed into any newly created ObjectStore's via the method
62       * setResourceFactoryMap()
63       */
64      protected DispatchingObjectStore(final Map nameToResourceFactoryMap) {
65          dispatchMap_ = Collections.EMPTY_MAP;
66          resourceFactoryMap_ = nameToResourceFactoryMap;
67      }
68  
69      /***
70       * Create an instance
71       * @param commandToStoreMap A map containing command to store mappings.  Keys
72       * and values must be class objects.
73       * @param nameToResourceFactoryMap keys are names, values are the
74       * resource factory objects that are represented by the name.  This map
75       * will be passed into any newly created ObjectStore's via the method
76       * setResourceFactoryMap()
77       */
78      public DispatchingObjectStore( final Map commandToStoreMap,
79                                     final Map nameToResourceFactoryMap ) {
80          assertNotNull("commandToStoreMap", commandToStoreMap);
81          assertNotNull("nameToResourceFactoryMap", nameToResourceFactoryMap);
82  
83          dispatchMap_ = commandToStoreMap;
84          resourceFactoryMap_ = nameToResourceFactoryMap;
85      }
86  
87  
88      /***
89       * Perform the dispatching.
90       *
91       * @param command The command to dispatch
92       * @return The result of the command after the other store has processed it
93       */
94      protected Object executeImpl(
95              final ObjectStoreCommand command ) {
96  
97          return findStore(command).execute(command);
98      }
99  
100 
101     /***
102      * Find the ObjectStore for the specified command
103      *
104      * @param command The command for which we are finding the store
105      * @return The object store
106      * @throws ObjectStoreCommandNotSupportedException If we cannot find a
107      * store for the specified command
108      * @throws ObjectStoreException if an error occurs when finding or
109      * creating an object store
110      */
111     protected ObjectStore findStore(
112             final ObjectStoreCommand command )
113         throws
114             ObjectStoreCommandNotSupportedException,
115             ObjectStoreException {
116 
117         final Class storeClass = (Class)dispatchMap_.get(command.getClass());
118         if( storeClass == null ) {
119             throw new ObjectStoreCommandNotSupportedException(command);
120         }
121 
122         try {
123             final ObjectStore store = (ObjectStore)storeClass.newInstance();
124             store.setResourceFactoryMap(resourceFactoryMap_);
125             return store;
126         }
127         catch( IllegalAccessException e ) {
128             throw new ObjectStoreException(e);
129         }
130         catch( final InstantiationException e ) {
131             throw new ObjectStoreException(e);
132         }
133     }
134 }