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 */ 017 package org.apache.commons.betwixt.strategy; 018 019 import java.io.Serializable; 020 021 import org.apache.commons.betwixt.Options; 022 import org.apache.commons.betwixt.expression.Context; 023 024 /** 025 * <p>Strategy class for string <-> object conversions. 026 * Implementations of this interface are used by Betwixt to perform 027 * string <-> object conversions. 028 * This performs only the most basic conversions. 029 * Most applications will use a subclass. 030 * </p> 031 * <p>It is strongly recommended that (in order to support round tripping) 032 * that <code>objectToString</code> and <code>stringToObject</code> 033 * are inverse functions. 034 * In other words, given the same flavour, context and type the applying 035 * objectToString to the result of stringToObject should be equal to the 036 * original input. 037 * </p> 038 * @author Robert Burrell Donkin 039 * @since 0.5 040 */ 041 public class ObjectStringConverter implements Serializable { 042 043 /** Standard name for option giving flavour */ 044 public static final String FLAVOUR_OPTION_NAME 045 = "org.apache.commons.betwixt.flavour"; 046 047 /** 048 * Converts an object to a string representation. 049 * This basic implementation returns object.toString() 050 * or an empty string if the given object is null. 051 * 052 * @param object the object to be converted, possibly null 053 * @param type the property class of the object, not null 054 * @param flavour a string allow symantic differences in formatting to be communicated 055 * @param context the context, not null 056 * @deprecated 0.7 use {@link #objectToString(Object, Class, Context)} instead. 057 * The preferred way to support flavours is by setting the 058 * <code>org.apache.commons.betwixt.FLAVOUR</code> option. 059 * This can then be retrieved by calling {@link Context#getOptions()} 060 * @return a String representation, not null 061 */ 062 public String objectToString(Object object, Class type, String flavour, Context context) { 063 if ( object != null ) { 064 return object.toString(); 065 } 066 return ""; 067 } 068 069 /** 070 * Converts a string representation to an object. 071 * It is acceptable for an implementation to return the string if it cannot convert 072 * the string to the given class type. 073 * This basic implementation just returns a string. 074 * 075 * @param value the String to be converted 076 * @param type the property class to be returned (if possible), not null 077 * @param flavour a string allow symantic differences in formatting to be communicated 078 * @param context the context, not null 079 * @deprecated 0.7 use {@link #stringToObject(String, Class, Context)} instead. 080 * The preferred way to support flavours is by setting the 081 * <code>org.apache.commons.betwixt.FLAVOUR</code> option. 082 * This can then be retrieved by calling {@link Context#getOptions()} 083 * @return an Object converted from the String, not null 084 */ 085 public Object stringToObject(String value, Class type, String flavour, Context context) { 086 return value; 087 } 088 089 090 /** 091 * Converts an object to a string representation. 092 * This basic implementation returns object.toString() 093 * or an empty string if the given object is null. 094 * 095 * @since 0.7 096 * @param object the object to be converted, possibly null 097 * @param type the property class of the object, not null 098 * @param context the context, not null 099 * @return a String representation, not null 100 */ 101 public String objectToString(Object object, Class type, Context context) { 102 String flavour = getFlavour(context); 103 return objectToString(object, type, flavour, context); 104 } 105 106 /** 107 * Converts a string representation to an object. 108 * It is acceptable for an implementation to return the string if it cannot convert 109 * the string to the given class type. 110 * This basic implementation just returns a string. 111 * 112 * @since 0.7 113 * @param value the String to be converted 114 * @param type the property class to be returned (if possible), not null 115 * @param context the context, not null 116 * @return an Object converted from the String, not null 117 */ 118 public Object stringToObject(String value, Class type, Context context) { 119 String flavour = getFlavour(context); 120 return stringToObject(value, type, flavour, context); 121 } 122 123 /** 124 * Gets the current flavour from the context. 125 * @param context <code>Context</code>, not null 126 */ 127 private String getFlavour(Context context) { 128 String flavour = null; 129 Options options = context.getOptions(); 130 if (options != null) { 131 flavour = options.getValue(FLAVOUR_OPTION_NAME); 132 } 133 return flavour; 134 } 135 }