001    // Copyright 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.record;
016    
017    import java.util.Collection;
018    import java.util.Iterator;
019    
020    import org.apache.hivemind.ApplicationRuntimeException;
021    import org.apache.hivemind.ErrorLog;
022    import org.apache.hivemind.util.Defense;
023    import org.apache.hivemind.util.PropertyUtils;
024    import org.apache.tapestry.IComponent;
025    import org.apache.tapestry.IPage;
026    import org.apache.tapestry.IRequestCycle;
027    import org.apache.tapestry.engine.IPageRecorder;
028    import org.apache.tapestry.event.ObservedChangeEvent;
029    import org.apache.tapestry.spec.IPropertySpecification;
030    
031    /**
032     * @author Howard M. Lewis Ship
033     * @since 4.0
034     */
035    public class PageRecorderImpl implements IPageRecorder
036    {
037        private String _pageName;
038    
039        private IRequestCycle _requestCycle;
040    
041        private PropertyPersistenceStrategySource _strategySource;
042    
043        private boolean _locked = false;
044    
045        private ErrorLog _log;
046    
047        public PageRecorderImpl(String pageName, IRequestCycle requestCycle,
048                PropertyPersistenceStrategySource strategySource, ErrorLog log)
049        {
050            Defense.notNull(pageName, "pageName");
051            Defense.notNull(requestCycle, "requestCycle");
052            Defense.notNull(strategySource, "strategySource");
053            Defense.notNull(log, "log");
054    
055            _pageName = pageName;
056            _requestCycle = requestCycle;
057            _strategySource = strategySource;
058            _log = log;
059        }
060    
061        public void commit()
062        {
063            _locked = true;
064        }
065    
066        public Collection getChanges()
067        {
068            return _strategySource.getAllStoredChanges(_pageName);
069        }
070    
071        public void rollback(IPage page)
072        {
073            Collection changes = getChanges();
074    
075            Iterator i = changes.iterator();
076    
077            while (i.hasNext())
078            {
079                PropertyChange change = (PropertyChange) i.next();
080    
081                applyChange(page, change);
082            }
083        }
084    
085        private void applyChange(IPage page, PropertyChange change)
086        {
087            String idPath = change.getComponentPath();
088    
089            IComponent component = (idPath == null) ? page : page.getNestedComponent(idPath);
090    
091            PropertyUtils.write(component, change.getPropertyName(), change.getNewValue());
092        }
093    
094        public void observeChange(ObservedChangeEvent event)
095        {
096            IComponent component = event.getComponent();
097            String propertyName = event.getPropertyName();
098    
099            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 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 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    }