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.enhance;
016    
017    import java.lang.reflect.Constructor;
018    
019    import org.apache.hivemind.ApplicationRuntimeException;
020    import org.apache.hivemind.Location;
021    import org.apache.hivemind.util.Defense;
022    import org.apache.tapestry.services.ComponentConstructor;
023    
024    /**
025     * @author Howard M. Lewis Ship
026     * @since 4.0
027     */
028    public class ComponentConstructorImpl implements ComponentConstructor
029    {
030        private Location _location;
031    
032        private Constructor _constructor;
033    
034        private Object[] _parameters;
035    
036        private String _classFabString;
037    
038        /**
039         * News instance of this class.
040         * 
041         * @param constructor
042         *            the constructor method to invoke
043         * @param parameters
044         *            the parameters to pass to the constructor. These are retained, not copied.
045         * @param classFabString
046         *            a string representing the generated class information, used for exception
047         *            reporting
048         * @param location
049         *            the location, used for exception reporting
050         */
051    
052        public ComponentConstructorImpl(Constructor constructor, Object[] parameters,
053                String classFabString, Location location)
054        {
055            Defense.notNull(constructor, "constructor");
056            _constructor = constructor;
057            _parameters = parameters;
058            _classFabString = classFabString;
059            _location = location;
060        }
061    
062        public Class getComponentClass()
063        {
064            return _constructor.getDeclaringClass();
065        }
066    
067        public Object newInstance()
068        {
069            try
070            {
071                Object result = _constructor.newInstance(_parameters);
072    
073                // Unlikely to generate an error if we can get through it once, so it's
074                // safe to release the big classFabString
075    
076                _classFabString = null;
077    
078                return result;
079            }
080            catch (Throwable ex)
081            {
082                throw new ApplicationRuntimeException(EnhanceMessages.instantiationFailure(
083                        _constructor,
084                        _parameters,
085                        _classFabString,
086                        ex), null, _location, ex);
087            }
088        }
089    
090    }