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 */ 017package 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 * @version $Id$ 031 * @since 1.4 032 */ 033public final class ClassConverter extends AbstractConverter { 034 035 /** 036 * Construct a <b>java.lang.Class</b> <i>Converter</i> that throws 037 * a <code>ConversionException</code> if an error occurs. 038 */ 039 public ClassConverter() { 040 super(); 041 } 042 043 /** 044 * Construct a <b>java.lang.Class</b> <i>Converter</i> that returns 045 * a default value if an error occurs. 046 * 047 * @param defaultValue The default value to be returned 048 * if the value to be converted is missing or an error 049 * occurs converting the value. 050 */ 051 public ClassConverter(final Object defaultValue) { 052 super(defaultValue); 053 } 054 055 /** 056 * Return the default type this <code>Converter</code> handles. 057 * 058 * @return The default type this <code>Converter</code> handles. 059 * @since 1.8.0 060 */ 061 @Override 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 @Override 074 protected String convertToString(final Object value) { 075 return (value instanceof Class) ? ((Class<?>)value).getName() : value.toString(); 076 } 077 078 /** 079 * <p>Convert the input object into a java.lang.Class.</p> 080 * 081 * @param <T> Target type of the conversion. 082 * @param type Data type to which this value should be converted. 083 * @param value The input value to be converted. 084 * @return The converted value. 085 * @throws Throwable if an error occurs converting to the specified type 086 * @since 1.8.0 087 */ 088 @Override 089 protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable { 090 if (Class.class.equals(type)) { 091 ClassLoader classLoader = Thread.currentThread() 092 .getContextClassLoader(); 093 if (classLoader != null) { 094 try { 095 return type.cast(classLoader.loadClass(value.toString())); 096 } catch (final ClassNotFoundException ex) { 097 // Don't fail, carry on and try this class's class loader 098 // (see issue# BEANUTILS-263) 099 } 100 } 101 102 // Try this class's class loader 103 classLoader = ClassConverter.class.getClassLoader(); 104 return type.cast(classLoader.loadClass(value.toString())); 105 } 106 107 throw conversionException(type, value); 108 } 109 110}