001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     * 
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     * 
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */ 
017    package org.apache.commons.betwixt.expression;
018    
019    import java.lang.reflect.Array;
020    import java.util.Collection;
021    
022    import org.apache.commons.logging.Log;
023    import org.apache.commons.logging.LogFactory;
024    
025    /**
026     * Abstracts common features for strongly typed <code>Updater</code>'s.
027     * Strongly type <code>Updater</code>'s perform conversions based on this
028     * the expected type before the bean update is invoked.
029     * @since 0.7
030     * @author <a href='http://commons.apache.org'>Apache Commons Team</a>, <a href='http://www.apache.org'>Apache Software Foundation</a>
031     */
032    public abstract class TypedUpdater implements Updater {
033    
034        /** Logger */
035        private static final Log log = LogFactory.getLog( TypedUpdater.class );
036    
037        
038        /** The type of the first parameter of the method */
039        private Class valueType;
040    
041        /** 
042         * Updates the current bean context with the given String value 
043         * @param context the Context to be updated
044         * @param newValue the update to this new value 
045         */
046        public void update(Context context, Object newValue) {
047                Object bean = context.getBean();
048                if ( bean != null ) {
049                    if ( newValue instanceof String ) {
050                        // try to convert into primitive types
051                        if ( log.isTraceEnabled() ) {
052                            log.trace("Converting primitive to " + valueType);
053                        }
054                        newValue = context.getObjectStringConverter()
055                            .stringToObject( (String) newValue, valueType, context );
056                    }
057                    if ( newValue != null ) {
058                        // check that it is of the correct type
059        /*                
060                        if ( ! valueType.isAssignableFrom( newValue.getClass() ) ) {
061                            log.warn( 
062                                "Cannot call setter method: " + method.getName() + " on bean: " + bean
063                                + " with type: " + bean.getClass().getName() 
064                                + " as parameter should be of type: " + valueType.getName() 
065                                + " but is: " + newValue.getClass().getName() 
066                            );
067                            return;
068                        }
069        */                
070                    }
071                    // special case for collection objects into arrays                    
072                    if (newValue instanceof Collection && valueType.isArray()) {
073                        Collection valuesAsCollection = (Collection) newValue;
074                        Class componentType = valueType.getComponentType();
075                        if (componentType != null) {
076                            Object[] valuesAsArray = 
077                                (Object[]) Array.newInstance(componentType, valuesAsCollection.size());
078                            newValue = valuesAsCollection.toArray(valuesAsArray);
079                        }
080                    }
081                    
082                    ;
083                    try {
084                        executeUpdate( context, bean, newValue );
085                        
086                    } catch (Exception e) {
087                        String valueTypeName = (newValue != null) ? newValue.getClass().getName() : "null";
088                        log.warn( 
089                            "Cannot evaluate: " + this.toString() + " on bean: " + bean 
090                            + " of type: " + bean.getClass().getName() + " with value: " + newValue 
091                            + " of type: " + valueTypeName 
092                        );
093                        handleException(context, e);
094                    }
095                }
096            }
097    
098        
099        
100        /**
101         * Gets the type expected.
102         * The value passed into {@link #update}
103         * will be converted on the basis of this type
104         * before being passed to {@link #executeUpdate}.
105         * @return <code>Class</code> giving expected type, not null
106         */
107        public Class getValueType() {
108            return valueType;
109        }
110        
111        /**
112         * Sets the type expected.
113         * The value passed into {@link #update}
114         * will be converted on the basis of this type
115         * before being passed to {@link #executeUpdate}.
116         * @param valueType <code>Class</code> giving expected type, not null
117         */
118        public void setValueType(Class valueType) {
119            this.valueType = valueType;
120        }
121        
122        /**
123         * Updates the bean with the given value.
124         * @param bean 
125         * @param value value after type conversion
126         */
127        protected abstract void executeUpdate(Context context, Object bean, Object value) throws Exception;
128    
129        /** 
130         * Strategy method to allow derivations to handle exceptions differently.
131         * @param context the Context being updated when this exception occured
132         * @param e the Exception that occured during the update
133         */
134        protected void handleException(Context context, Exception e) {
135            log.info( "Caught exception: " + e, e );
136        }
137        
138    }