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Java > Open Source Codes > org > apache > tapestry > record > PageRecorderImpl


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.record;
16
17 import java.util.Collection JavaDoc;
18 import java.util.Iterator JavaDoc;
19
20 import org.apache.hivemind.ApplicationRuntimeException;
21 import org.apache.hivemind.ErrorLog;
22 import org.apache.hivemind.util.Defense;
23 import org.apache.hivemind.util.PropertyUtils;
24 import org.apache.tapestry.IComponent;
25 import org.apache.tapestry.IPage;
26 import org.apache.tapestry.IRequestCycle;
27 import org.apache.tapestry.engine.IPageRecorder;
28 import org.apache.tapestry.event.ObservedChangeEvent;
29 import org.apache.tapestry.spec.IPropertySpecification;
30
31 /**
32  * @author Howard M. Lewis Ship
33  * @since 4.0
34  */
35 public class PageRecorderImpl implements IPageRecorder
36 {
37     private String JavaDoc _pageName;
38
39     private IRequestCycle _requestCycle;
40
41     private PropertyPersistenceStrategySource _strategySource;
42
43     private boolean _locked = false;
44
45     private ErrorLog _log;
46
47     public PageRecorderImpl(String JavaDoc pageName, IRequestCycle requestCycle,
48             PropertyPersistenceStrategySource strategySource, ErrorLog log)
49     {
50         Defense.notNull(pageName, "pageName");
51         Defense.notNull(requestCycle, "requestCycle");
52         Defense.notNull(strategySource, "strategySource");
53         Defense.notNull(log, "log");
54
55         _pageName = pageName;
56         _requestCycle = requestCycle;
57         _strategySource = strategySource;
58         _log = log;
59     }
60
61     public void commit()
62     {
63         _locked = true;
64     }
65
66     public Collection JavaDoc getChanges()
67     {
68         return _strategySource.getAllStoredChanges(_pageName, _requestCycle);
69     }
70
71     public void rollback(IPage page)
72     {
73         Collection JavaDoc changes = getChanges();
74
75         Iterator JavaDoc i = changes.iterator();
76
77         while (i.hasNext())
78         {
79             PropertyChange change = (PropertyChange) i.next();
80
81             applyChange(page, change);
82         }
83     }
84
85     private void applyChange(IPage page, PropertyChange change)
86     {
87         String JavaDoc idPath = change.getComponentPath();
88
89         IComponent component = (idPath == null) ? page : page.getNestedComponent(idPath);
90
91         PropertyUtils.write(component, change.getPropertyName(), change.getNewValue());
92     }
93
94     public void observeChange(ObservedChangeEvent event)
95     {
96         IComponent component = event.getComponent();
97         String JavaDoc propertyName = event.getPropertyName();
98
99         if (_locked)
100         {
101             _log.error(RecordMessages.recorderLocked(propertyName, component), null, null);
102             return;
103         }
104
105         PropertyPersistenceStrategy strategy = findStrategy(component, propertyName);
106
107         if (strategy != null)
108             strategy.store(_pageName, component.getIdPath(), propertyName, event.getNewValue());
109     }
110
111     // package private for testing
112
113     PropertyPersistenceStrategy findStrategy(IComponent component, String JavaDoc propertyName)
114     {
115         // So much for Law of Demeter!
116
117         IPropertySpecification propertySpecification = component.getSpecification()
118                 .getPropertySpecification(propertyName);
119
120         if (propertySpecification == null)
121         {
122             _log.error(
123                     RecordMessages.missingPropertySpecification(propertyName, component),
124                     null,
125                     null);
126             return null;
127         }
128
129         String JavaDoc name = propertySpecification.getPersistence();
130
131         // Should check for nulls, but the architecture of the framework pretty much
132 // ensures that we won't get here unless there is a property
133 // and a persistence value for the property.
134
135         try
136         {
137             return _strategySource.getStrategy(name);
138         }
139         catch (ApplicationRuntimeException ex)
140         {
141             _log.error(ex.getMessage(), propertySpecification.getLocation(), ex);
142
143             return null;
144         }
145     }
146
147 }
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