001    // Copyright 2004, 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.services.impl;
016    
017    import java.util.Collections;
018    import java.util.HashMap;
019    import java.util.Map;
020    
021    import org.apache.commons.logging.Log;
022    import org.apache.hivemind.ClassResolver;
023    import org.apache.hivemind.service.ClassFactory;
024    import org.apache.tapestry.enhance.EnhancedClassValidator;
025    import org.apache.tapestry.enhance.EnhancementOperationImpl;
026    import org.apache.tapestry.enhance.EnhancementWorker;
027    import org.apache.tapestry.event.ResetEventListener;
028    import org.apache.tapestry.services.ComponentConstructor;
029    import org.apache.tapestry.services.ComponentConstructorFactory;
030    import org.apache.tapestry.spec.IComponentSpecification;
031    
032    /**
033     * Implementation of the {@link org.apache.tapestry.services.ComponentConstructorFactory} service
034     * interface.
035     * 
036     * @author Howard M. Lewis Ship
037     * @since 4.0
038     */
039    public class ComponentConstructorFactoryImpl implements ComponentConstructorFactory,
040            ResetEventListener
041    {
042        private Log _log;
043        
044        private ClassFactory _classFactory;
045    
046        private ClassResolver _classResolver;
047    
048        private EnhancedClassValidator _validator;
049    
050        private EnhancementWorker _chain;
051    
052        /**
053         * Map of {@link org.apache.tapestry.services.ComponentConstructor}keyed on
054         * {@link org.apache.tapestry.spec.IComponentSpecification}.
055         */
056    
057        private Map _cachedConstructors = Collections.synchronizedMap(new HashMap());
058    
059        public void resetEventDidOccur()
060        {
061            _cachedConstructors.clear();
062        }
063    
064        public ComponentConstructor getComponentConstructor(IComponentSpecification specification,
065                String className)
066        {
067            ComponentConstructor result = (ComponentConstructor) _cachedConstructors.get(specification);
068    
069            if (result == null)
070            {
071                Class baseClass = _classResolver.findClass(className);
072    
073                EnhancementOperationImpl eo = new EnhancementOperationImpl(_classResolver,
074                        specification, baseClass, _classFactory, _log);
075    
076                // Invoking on the chain is the same as invoking on every
077                // object in the chain (because method performEnhancement() is type void).
078    
079                _chain.performEnhancement(eo, specification);
080    
081                result = eo.getConstructor();
082    
083                // TODO: This should be optional to work around that IBM JVM bug.
084                // Also, to some degree, it should be passed into EnhancementOperationImpl,
085                // as it generally only needs to be done if a enhanced class
086                // is fabricated.
087    
088                _validator.validate(baseClass, result.getComponentClass(), specification);
089    
090                _cachedConstructors.put(specification, result);
091            }
092    
093            return result;
094        }
095    
096        public void setClassFactory(ClassFactory classFactory)
097        {
098            _classFactory = classFactory;
099        }
100    
101        public void setClassResolver(ClassResolver classResolver)
102        {
103            _classResolver = classResolver;
104        }
105    
106        public void setValidator(EnhancedClassValidator validator)
107        {
108            _validator = validator;
109        }
110    
111        public void setChain(EnhancementWorker chain)
112        {
113            _chain = chain;
114        }
115    
116        public void setLog(Log log)
117        {
118            _log = log;
119        }
120    }