Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
Converter |
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1 | /* | |
2 | * Copyright 2004 The Apache Software Foundation | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | package org.apache.commons.convert; | |
17 | ||
18 | /** | |
19 | * Converter is the central class that holds a set of registered converters | |
20 | * together and allows conversion to occur. | |
21 | * <p> | |
22 | * This class allows applications to add their own converters. This is achieved | |
23 | * by creating a new instance and using that within the application. Generally, | |
24 | * the instance is stored in a static variable in the application. | |
25 | * <p> | |
26 | * In this way, the application remains independent of other converters used | |
27 | * by other applications or libraries. | |
28 | * | |
29 | * @author Stephen Colebourne | |
30 | * @version $Id: Converter.java 155441 2005-02-26 13:19:22Z dirkv $ | |
31 | * @since 1.0 | |
32 | */ | |
33 | public class Converter { | |
34 | ||
35 | /* The converter registry */ | |
36 | private final ConversionRegistry registry; | |
37 | ||
38 | /** | |
39 | * Constructs a new instance of the Converter useful to create a set | |
40 | * of conversions separate from the default set. | |
41 | * <p> | |
42 | * The created converter has no conversions registered. | |
43 | */ | |
44 | public Converter() { | |
45 | 0 | this(false); |
46 | 0 | } |
47 | ||
48 | /** | |
49 | * Constructs a new instance of the Converter useful to create a set | |
50 | * of conversions separate from the default set. | |
51 | * | |
52 | * @param addDefaults whether to add the default conversions | |
53 | */ | |
54 | public Converter(boolean addDefaults) { | |
55 | 0 | super(); |
56 | 0 | registry = createRegistry(); |
57 | 0 | if (addDefaults) { |
58 | 0 | registry.addDefaultConversions(); |
59 | } | |
60 | 0 | } |
61 | ||
62 | /** | |
63 | * Factory method for subclasses to change the registry implementation. | |
64 | * | |
65 | * @return a new, non-null, registry | |
66 | */ | |
67 | protected ConversionRegistry createRegistry() { | |
68 | 0 | return new ConversionRegistry(); |
69 | } | |
70 | ||
71 | //----------------------------------------------------------------------- | |
72 | /** | |
73 | * Convert the specified input object into an output object | |
74 | * of the another type. | |
75 | * | |
76 | * @param value the input value to be converted | |
77 | * @param fromClass the class to convert from, useful if null passed in | |
78 | * @param toClass the class to convert to | |
79 | * @return the converted value | |
80 | * @throws ConversionException (runtime) if conversion fails | |
81 | */ | |
82 | public Object convert(Object value, Class fromClass, Class toClass) { | |
83 | 0 | return doConversion(value, fromClass, toClass); |
84 | } | |
85 | ||
86 | /** | |
87 | * Convert the specified input object into an output object | |
88 | * of the another type. | |
89 | * | |
90 | * @param value the input value to be converted | |
91 | * @param toClass the class to convert to | |
92 | * @return the converted value | |
93 | * @throws ConversionException (runtime) if conversion fails | |
94 | */ | |
95 | public Object convert(Object value, Class toClass) { | |
96 | 0 | return doConversion(value, null, toClass); |
97 | } | |
98 | ||
99 | /** | |
100 | * Convert the specified input object into a <code>String</code>. | |
101 | * | |
102 | * @param value the input value to be converted | |
103 | * @param fromClass the class to convert from, useful if null passed in | |
104 | * @return the converted value | |
105 | * @throws ConversionException (runtime) if conversion fails | |
106 | */ | |
107 | public String convertToString(Object value, Class fromClass) { | |
108 | 0 | return (String) doConversion(value, fromClass, String.class); |
109 | } | |
110 | ||
111 | /** | |
112 | * Convert the specified input object into a <code>String</code>. | |
113 | * | |
114 | * @param value the input value to be converted | |
115 | * @return the converted value | |
116 | * @throws ConversionException (runtime) if conversion fails | |
117 | */ | |
118 | public String convertToString(Object value) { | |
119 | 0 | return (String) doConversion(value, null, String.class); |
120 | } | |
121 | ||
122 | //----------------------------------------------------------------------- | |
123 | /** | |
124 | * Convert the specified input object into an output object of another type. | |
125 | * <p> | |
126 | * This implementation uses {{@link #doConversion(Conversion, Object)}. | |
127 | * | |
128 | * @param value the input value to be converted | |
129 | * @param fromClass the class to convert from, useful if null passed in | |
130 | * @param toClass the class to convert to | |
131 | * @return the converted value | |
132 | * @throws ConversionException (runtime) if conversion fails | |
133 | */ | |
134 | protected Object doConversion(Object value, Class fromClass, Class toClass) { | |
135 | 0 | Class valueClass = (value == null ? fromClass : value.getClass()); |
136 | 0 | Conversion conv = getRegistry().getConversion(value, valueClass, toClass); |
137 | 0 | if (conv == null) { |
138 | 0 | throw new ConversionException("No Converter found to convert " + valueClass + " to " + toClass); |
139 | } | |
140 | 0 | return doConversion(conv, value); |
141 | } | |
142 | ||
143 | /** | |
144 | * Convert the specified input object into an output object using the conversion. | |
145 | * <p> | |
146 | * This implementation catches exceptions and wraps them in a <code>ConversionException</code>. | |
147 | * | |
148 | * @param conversion the conversion to use | |
149 | * @param value the value to convert | |
150 | * @return the converted value | |
151 | * @throws ConversionException (runtime) if conversion fails | |
152 | */ | |
153 | protected Object doConversion(Conversion conversion, Object value) { | |
154 | try { | |
155 | 0 | return conversion.convert(value, this); |
156 | ||
157 | 0 | } catch (ConversionException ex) { |
158 | 0 | throw ex; |
159 | 0 | } catch (Exception ex) { |
160 | 0 | throw new ConversionException(conversion.toString(), ex); |
161 | } | |
162 | } | |
163 | ||
164 | //----------------------------------------------------------------------- | |
165 | /** | |
166 | * Gets the converter registry used for adding and removing converters. | |
167 | * | |
168 | * @return the converter registry, never null | |
169 | */ | |
170 | public ConversionRegistry getRegistry() { | |
171 | 0 | return registry; |
172 | } | |
173 | ||
174 | //----------------------------------------------------------------------- | |
175 | /** | |
176 | * Returns a string describing this object. | |
177 | * | |
178 | * @return a string describing this object | |
179 | */ | |
180 | public String toString() { | |
181 | 0 | return "Converter"; |
182 | } | |
183 | ||
184 | } |