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 }