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} 021 * implementation that converts an incoming 022 * object into a <code>java.lang.String</code> object. 023 * <p> 024 * Note that ConvertUtils really is designed to do string->object conversions, 025 * and offers very little support for object->string conversions. The 026 * ConvertUtils/ConvertUtilsBean methods only select a converter to apply 027 * based upon the target type being converted to, and generally assume that 028 * the input is a string (by calling its toString method if needed). 029 * <p> 030 * This class is therefore just a dummy converter that converts its input 031 * into a string by calling the input object's toString method and returning 032 * that value. 033 * <p> 034 * It is possible to replace this converter with something that has a big 035 * if/else statement that selects behaviour based on the real type of the 036 * object being converted (or possibly has a map of converters, and looks 037 * them up based on the class of the input object). However this is not part 038 * of the existing ConvertUtils framework. 039 * 040 * 041 * @version $Id$ 042 * @since 1.3 043 */ 044public final class StringConverter extends AbstractConverter { 045 046 047 /** 048 * Construct a <b>java.lang.String</b> <i>Converter</i> that throws 049 * a <code>ConversionException</code> if an error occurs. 050 */ 051 public StringConverter() { 052 super(); 053 } 054 055 /** 056 * Construct a <b>java.lang.String</b> <i>Converter</i> that returns 057 * a default value if an error occurs. 058 * 059 * @param defaultValue The default value to be returned 060 * if the value to be converted is missing or an error 061 * occurs converting the value. 062 */ 063 public StringConverter(final Object defaultValue) { 064 super(defaultValue); 065 } 066 067 /** 068 * Return the default type this <code>Converter</code> handles. 069 * 070 * @return The default type this <code>Converter</code> handles. 071 * @since 1.8.0 072 */ 073 @Override 074 protected Class<?> getDefaultType() { 075 return String.class; 076 } 077 078 /** 079 * Convert the specified input object into an output object of the 080 * specified type. 081 * 082 * @param <T> Target type of the conversion. 083 * @param type Data type to which this value should be converted. 084 * @param value The input value to be converted. 085 * @return The converted value. 086 * @throws Throwable if an error occurs converting to the specified type 087 * @since 1.8.0 088 */ 089 @Override 090 protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable { 091 // We have to support Object, too, because this class is sometimes 092 // used for a standard to Object conversion 093 if (String.class.equals(type) || Object.class.equals(type)) { 094 return type.cast(value.toString()); 095 } 096 throw conversionException(type, value); 097 } 098 099 100}