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} implementation that handles conversion 021 * to and from <strong>java.lang.Class</strong> 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 <em>default value</em> or throw a 028 * <code>ConversionException</code> if a conversion error occurs. 029 * 030 * @since 1.4 031 */ 032public final class ClassConverter extends AbstractConverter { 033 034 /** 035 * Construct a <strong>java.lang.Class</strong> <em>Converter</em> that throws 036 * a <code>ConversionException</code> if an error occurs. 037 */ 038 public ClassConverter() { 039 } 040 041 /** 042 * Construct a <strong>java.lang.Class</strong> <em>Converter</em> that returns 043 * a default value if an error occurs. 044 * 045 * @param defaultValue The default value to be returned 046 * if the value to be converted is missing or an error 047 * occurs converting the value. 048 */ 049 public ClassConverter(final Object defaultValue) { 050 super(defaultValue); 051 } 052 053 /** 054 * <p>Convert a java.lang.Class or object into a String.</p> 055 * 056 * @param value The input value to be converted 057 * @return the converted String value. 058 * @since 1.8.0 059 */ 060 @Override 061 protected String convertToString(final Object value) { 062 return value instanceof Class ? ((Class<?>)value).getName() : value.toString(); 063 } 064 065 /** 066 * <p>Convert the input object into a java.lang.Class.</p> 067 * 068 * @param <T> Target type of the conversion. 069 * @param type Data type to which this value should be converted. 070 * @param value The input value to be converted. 071 * @return The converted value. 072 * @throws Throwable if an error occurs converting to the specified type 073 * @since 1.8.0 074 */ 075 @Override 076 protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable { 077 if (Class.class.equals(type)) { 078 ClassLoader classLoader = Thread.currentThread() 079 .getContextClassLoader(); 080 if (classLoader != null) { 081 try { 082 return type.cast(classLoader.loadClass(value.toString())); 083 } catch (final ClassNotFoundException ex) { 084 // Don't fail, carry on and try this class's class loader 085 // (see issue# BEANUTILS-263) 086 } 087 } 088 089 // Try this class's class loader 090 classLoader = ClassConverter.class.getClassLoader(); 091 return type.cast(classLoader.loadClass(value.toString())); 092 } 093 094 throw conversionException(type, value); 095 } 096 097 /** 098 * Return the default type this <code>Converter</code> handles. 099 * 100 * @return The default type this <code>Converter</code> handles. 101 * @since 1.8.0 102 */ 103 @Override 104 protected Class<?> getDefaultType() { 105 return Class.class; 106 } 107 108}