001    /*
002     *  Copyright 2003-2004 The Apache Software Foundation
003     *
004     *  Licensed under the Apache License, Version 2.0 (the "License");
005     *  you may not use this file except in compliance with the License.
006     *  You may obtain a copy of the License at
007     *
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     *
010     *  Unless required by applicable law or agreed to in writing, software
011     *  distributed under the License is distributed on an "AS IS" BASIS,
012     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     *  See the License for the specific language governing permissions and
014     *  limitations under the License.
015     */
016    package org.apache.commons.convert1.array;
017    
018    import java.lang.reflect.Array;
019    import java.util.List;
020    import java.util.Iterator;
021    
022    import org.apache.commons.convert1.ConversionException;
023    import org.apache.commons.convert1.Converter;
024    
025    import org.apache.commons.convert1.ConvertRegistry;
026    
027    
028    /**
029     * <p>Standard {@link Converter} implementation that converts an incoming
030     * comma delimited String into a known Java class via another Converter.
031     *
032     * @author Henri Yandell
033     * @version $Id: ArrayConverter.java 155441 2005-02-26 13:19:22Z dirkv $
034     * @since 0.1
035     */
036    public class ArrayConverter implements Converter {
037    
038        private ConvertRegistry registry;
039        private Converter converter;
040    
041        /**
042         * Handles multiple types of sub-type by reusing a 
043         * particular registry for the sub-elements. 
044         */
045        public ArrayConverter(ConvertRegistry registry) {
046            this.registry = registry;
047        }
048    
049        /**
050         * Handles only one type of element converter. 
051         */
052        public ArrayConverter(Converter converter) {
053            this.converter = converter;
054        }
055    
056        /**
057         * Convert the specified input object into an output object of the
058         * specified type.
059         *
060         * @param type Data type to which this value should be converted
061         * @param value The input value to be converted
062         *
063         * @exception ConversionException if conversion cannot be performed
064         *  successfully
065         */
066        public Object convert(Class toClass, Object value) {
067    
068            if (value == null) {
069                return null;   // ignore defaults for the moment
070            }
071    
072            // parse the comma delimitation.
073            //H? can we abstract this somehow?
074            //   An ElementProvider?
075            List elements = StringArrayParser.parseElements(value.toString());
076    
077            // assume that toClass is an array??
078            if( toClass.isArray() ) {
079                toClass = toClass.getComponentType();
080            }
081            Object array = Array.newInstance( toClass, elements.size() );
082    
083            if(registry != null) {
084                converter = this.registry.lookup( String.class, toClass );
085            }
086    
087            Iterator itr = elements.iterator();
088            int idx = 0;
089            while(itr.hasNext()) {
090                Array.set( array, idx, converter.convert( toClass, itr.next() ) );
091                idx++;
092            }
093    
094            return array;
095        }
096    
097    }