    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.beanutils.converters;
    018
    019    /**
    020     * {@link org.apache.commons.beanutils.Converter} implementaion that handles conversion
    021     * to and from <b>java.lang.Class</b> objects.
    022     * <p>
    023     * The class will be loaded from the thread context class
    024     * loader (if it exists); otherwise the class loader that loaded this class
    025     * will be used.
    026     * <p>
    027     * Can be configured to either return a <i>default value</i> or throw a
    028     * <code>ConversionException</code> if a conversion error occurs.
    029     *
    030     * @author Tomas Viberg
    031     * @version $Revision: 690380 $ $Date: 2008-08-29 21:04:38 +0100 (Fri, 29 Aug 2008) $
    032     * @since 1.4
    033     */
    034    public final class ClassConverter extends AbstractConverter {
    035
    036        /**
    037         * Construct a <b>java.lang.Class</b> <i>Converter</i> that throws
    038         * a <code>ConversionException</code> if an error occurs.
    039         */
    040        public ClassConverter() {
    041            super();
    042        }
    043
    044        /**
    045         * Construct a <b>java.lang.Class</b> <i>Converter</i> that returns
    046         * a default value if an error occurs.
    047         *
    048         * @param defaultValue The default value to be returned
    049         * if the value to be converted is missing or an error
    050         * occurs converting the value.
    051         */
    052        public ClassConverter(Object defaultValue) {
    053            super(defaultValue);
    054        }
    055
    056        /**
    057         * Return the default type this <code>Converter</code> handles.
    058         *
    059         * @return The default type this <code>Converter</code> handles.
    060         * @since 1.8.0
    061         */
    062        protected Class getDefaultType() {
    063            return Class.class;
    064        }
    065
    066        /**
    067         * <p>Convert a java.lang.Class or object into a String.</p>
    068         *
    069         * @param value The input value to be converted
    070         * @return the converted String value.
    071         * @since 1.8.0
    072         */
    073        protected String convertToString(Object value) {
    074            return (value instanceof Class) ? ((Class)value).getName() : value.toString();
    075        }
    076
    077        /**
    078         * <p>Convert the input object into a java.lang.Class.</p>
    079         *
    080         * @param type Data type to which this value should be converted.
    081         * @param value The input value to be converted.
    082         * @return The converted value.
    083         * @throws Throwable if an error occurs converting to the specified type
    084         * @since 1.8.0
    085         */
    086        protected Object convertToType(Class type, Object value) throws Throwable {
    087            ClassLoader classLoader =
    088                Thread.currentThread().getContextClassLoader();
    089            if (classLoader != null) {
    090                try {
    091                    return (classLoader.loadClass(value.toString()));
    092                } catch (ClassNotFoundException ex) {
    093                    // Don't fail, carry on and try this class's class loader
    094                    // (see issue# BEANUTILS-263)
    095                }
    096            }
    097
    098            // Try this class's class loader
    099            classLoader = ClassConverter.class.getClassLoader();
    100            return (classLoader.loadClass(value.toString()));
    101        }
    102
    103    }