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}
21 * implementation that converts an incoming
22 * object into a <code>java.lang.String</code> object.
23 * <p>
24 * Note that ConvertUtils really is designed to do string->object conversions,
25 * and offers very little support for object->string conversions. The
26 * ConvertUtils/ConvertUtilsBean methods only select a converter to apply
27 * based upon the target type being converted to, and generally assume that
28 * the input is a string (by calling its toString method if needed).
29 * <p>
30 * This class is therefore just a dummy converter that converts its input
31 * into a string by calling the input object's toString method and returning
32 * that value.
33 * <p>
34 * It is possible to replace this converter with something that has a big
35 * if/else statement that selects behaviour based on the real type of the
36 * object being converted (or possibly has a map of converters, and looks
37 * them up based on the class of the input object). However this is not part
38 * of the existing ConvertUtils framework.
39 *
40 *
41 * @version $Id$
42 * @since 1.3
43 */
44 public final class StringConverter extends AbstractConverter {
45
46
47 /**
48 * Construct a <b>java.lang.String</b> <i>Converter</i> that throws
49 * a <code>ConversionException</code> if an error occurs.
50 */
51 public StringConverter() {
52 super();
53 }
54
55 /**
56 * Construct a <b>java.lang.String</b> <i>Converter</i> that returns
57 * a default value if an error occurs.
58 *
59 * @param defaultValue The default value to be returned
60 * if the value to be converted is missing or an error
61 * occurs converting the value.
62 */
63 public StringConverter(final Object defaultValue) {
64 super(defaultValue);
65 }
66
67 /**
68 * Return the default type this <code>Converter</code> handles.
69 *
70 * @return The default type this <code>Converter</code> handles.
71 * @since 1.8.0
72 */
73 @Override
74 protected Class<?> getDefaultType() {
75 return String.class;
76 }
77
78 /**
79 * Convert the specified input object into an output object of the
80 * specified type.
81 *
82 * @param <T> Target type of the conversion.
83 * @param type Data type to which this value should be converted.
84 * @param value The input value to be converted.
85 * @return The converted value.
86 * @throws Throwable if an error occurs converting to the specified type
87 * @since 1.8.0
88 */
89 @Override
90 protected <T> T convertToType(final Class<T> type, final Object value) throws Throwable {
91 // We have to support Object, too, because this class is sometimes
92 // used for a standard to Object conversion
93 if (String.class.equals(type) || Object.class.equals(type)) {
94 return type.cast(value.toString());
95 }
96 throw conversionException(type, value);
97 }
98
99
100 }