1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.beanutils.converters; 18 19 /** 20 * {@link org.apache.commons.beanutils.Converter} implementaion that handles conversion 21 * to and from <b>java.lang.Class</b> objects. 22 * <p> 23 * The class will be loaded from the thread context class 24 * loader (if it exists); otherwise the class loader that loaded this class 25 * will be used. 26 * <p> 27 * Can be configured to either return a <i>default value</i> or throw a 28 * <code>ConversionException</code> if a conversion error occurs. 29 * 30 * @version $Id$ 31 * @since 1.4 32 */ 33 public final class ClassConverter extends AbstractConverter { 34 35 /** 36 * Construct a <b>java.lang.Class</b> <i>Converter</i> that throws 37 * a <code>ConversionException</code> if an error occurs. 38 */ 39 public ClassConverter() { 40 super(); 41 } 42 43 /** 44 * Construct a <b>java.lang.Class</b> <i>Converter</i> that returns 45 * a default value if an error occurs. 46 * 47 * @param defaultValue The default value to be returned 48 * if the value to be converted is missing or an error 49 * occurs converting the value. 50 */ 51 public ClassConverter(final Object defaultValue) { 52 super(defaultValue); 53 } 54 55 /** 56 * Return the default type this <code>Converter</code> handles. 57 * 58 * @return The default type this <code>Converter</code> handles. 59 * @since 1.8.0 60 */ 61 @Override 62 protected Class<?> getDefaultType() { 63 return Class.class; 64 } 65 66 /** 67 * <p>Convert a java.lang.Class or object into a String.</p> 68 * 69 * @param value The input value to be converted 70 * @return the converted String value. 71 * @since 1.8.0 72 */ 73 @Override 74 protected String convertToString(final Object value) { 75 return (value instanceof Class) ? ((Class<?>)value).getName() : value.toString(); 76 } 77 78 /** 79 * <p>Convert the input object into a java.lang.Class.</p> 80 * 81 * @param <T> Target type of the conversion. 82 * @param type Data type to which this value should be converted. 83 * @param value The input value to be converted. 84 * @return The converted value. 85 * @throws Throwable if an error occurs converting to the specified type 86 * @since 1.8.0 87 */ 88 @Override 89 protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable { 90 if (Class.class.equals(type)) { 91 ClassLoader classLoader = Thread.currentThread() 92 .getContextClassLoader(); 93 if (classLoader != null) { 94 try { 95 return type.cast(classLoader.loadClass(value.toString())); 96 } catch (final ClassNotFoundException ex) { 97 // Don't fail, carry on and try this class's class loader 98 // (see issue# BEANUTILS-263) 99 } 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 }