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 to object conversions, 025 * and offers very little support for object to 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 * @since 1.3 042 */ 043public final class StringConverter extends AbstractConverter { 044 045 /** 046 * Construct a <strong>java.lang.String</strong> <em>Converter</em> that throws 047 * a <code>ConversionException</code> if an error occurs. 048 */ 049 public StringConverter() { 050 } 051 052 /** 053 * Construct a <strong>java.lang.String</strong> <em>Converter</em> that returns 054 * a default value if an error occurs. 055 * 056 * @param defaultValue The default value to be returned 057 * if the value to be converted is missing or an error 058 * occurs converting the value. 059 */ 060 public StringConverter(final Object defaultValue) { 061 super(defaultValue); 062 } 063 064 /** 065 * Convert the specified input object into an output object of the 066 * specified type. 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 // We have to support Object, too, because this class is sometimes 078 // used for a standard to Object conversion 079 if (String.class.equals(type) || Object.class.equals(type)) { 080 return type.cast(value.toString()); 081 } 082 throw conversionException(type, value); 083 } 084 085 /** 086 * Return the default type this <code>Converter</code> handles. 087 * 088 * @return The default type this <code>Converter</code> handles. 089 * @since 1.8.0 090 */ 091 @Override 092 protected Class<?> getDefaultType() { 093 return String.class; 094 } 095 096}