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.bean;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.tapestry.IBeanProvider;
019    import org.apache.tapestry.IComponent;
020    import org.apache.tapestry.services.ExpressionEvaluator;
021    
022    /**
023     * Initializes a helper bean property from an OGNL expression (relative to the bean's
024     * {@link IComponent}).
025     * 
026     * @author Howard Lewis Ship
027     * @since 2.2
028     */
029    
030    public class ExpressionBeanInitializer extends AbstractBeanInitializer
031    {
032        protected String _expression;
033    
034        private final ExpressionEvaluator _evaluator;
035    
036        public ExpressionBeanInitializer(ExpressionEvaluator evaluator)
037        {
038            _evaluator = evaluator;
039        }
040    
041        public void setBeanProperty(IBeanProvider provider, Object bean)
042        {
043            IComponent component = provider.getComponent();
044    
045            try
046            {
047                Object value = _evaluator.read(component, _expression);
048    
049                setBeanProperty(bean, value);
050            }
051            catch (Exception ex)
052            {
053                throw new ApplicationRuntimeException(ex.getMessage(), getLocation(), ex);
054            }
055        }
056    
057        /** @since 3.0 * */
058    
059        public String getExpression()
060        {
061            return _expression;
062        }
063    
064        /** @since 3.0 * */
065    
066        public void setExpression(String expression)
067        {
068            _expression = expression;
069        }
070    
071    }