DeferredObjectImpl


1   // Copyright 2005 The Apache Software Foundation
2   //
3   // Licensed under the Apache License, Version 2.0 (the "License");
4   // you may not use this file except in compliance with the License.
5   // You may obtain a copy of the License at
6   //
7   //     http://www.apache.org/licenses/LICENSE-2.0
8   //
9   // Unless required by applicable law or agreed to in writing, software
10  // distributed under the License is distributed on an "AS IS" BASIS,
11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  
15  package org.apache.tapestry.services.impl;
16  
17  import org.apache.hivemind.Location;
18  import org.apache.hivemind.internal.Module;
19  import org.apache.hivemind.schema.Translator;
20  
21  /**
22   * An encapsulation of an invocation of
23   * {@link org.apache.hivemind.schema.Translator#translate(org.apache.hivemind.internal.Module, java.lang.Class, java.lang.String, org.apache.hivemind.Location)},
24   * allowing the actual invocation (and all the object creation, etc., that entails) to be deferred,
25   * or even avoided all together.
26   * 
27   * @author Howard M. Lewis Ship
28   * @since 4.0
29   */
30  public class DeferredObjectImpl implements DeferredObject
31  {
32      private final Module _module;
33  
34      private final Translator _objectTranslator;
35  
36      private final String   _objectReference;
37  
38      private final Location _location;
39  
40      private Object   _object;
41  
42      public DeferredObjectImpl(final Translator objectTranslator, final Module module,
43              final String   objectReference, final Location location)
44      {
45          _objectTranslator = objectTranslator;
46          _module = module;
47          _objectReference = objectReference;
48          _location = location;
49      }
50  
51      public synchronized Object   getObject()
52      {
53          if (_object == null)
54              _object = _objectTranslator.translate(
55                      _module,
56                      Object  .class,
57                      _objectReference,
58                      _location);
59  
60          return _object;
61      }
62  
63      public Location getLocation()
64      {
65          return _location;
66      }
67  }
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