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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} implementaion that handles conversion
21   * to and from <b>java.lang.Class</b> objects.
22   * <p>
23   * The class will be loaded from the thread context class
24   * loader (if it exists); otherwise the class loader that loaded this class
25   * will be used.
26   * <p>
27   * Can be configured to either return a <i>default value</i> or throw a
28   * <code>ConversionException</code> if a conversion error occurs.
29   *
30   * @author Tomas Viberg
31   * @version $Revision: 555845 $ $Date: 2007-07-13 03:52:05 +0100 (Fri, 13 Jul 2007) $
32   * @since 1.4
33   */
34  public final class ClassConverter extends AbstractConverter {
35  
36      /***
37       * Construct a <b>java.lang.Class</b> <i>Converter</i> that throws
38       * a <code>ConversionException</code> if an error occurs.
39       */
40      public ClassConverter() {
41          super(Class.class);
42      }
43  
44      /***
45       * Construct a <b>java.lang.Class</b> <i>Converter</i> that returns
46       * a default value if an error occurs.
47       *
48       * @param defaultValue The default value to be returned
49       * if the value to be converted is missing or an error
50       * occurs converting the value.
51       */
52      public ClassConverter(Object defaultValue) {
53          super(Class.class, defaultValue);
54      }
55  
56      /***
57       * <p>Convert a java.lang.Class or object into a String.</p>
58       *
59       * @param value The input value to be converted
60       * @return the converted String value.
61       */
62      protected String convertToString(Object value) {
63          return (value instanceof Class) ? ((Class)value).getName() : value.toString();
64      }
65  
66      /***
67       * <p>Convert the input object into a java.lang.Class.</p>
68       *
69       * @param type Data type to which this value should be converted.
70       * @param value The input value to be converted.
71       * @return The converted value.
72       * @throws Throwable if an error occurs converting to the specified type
73       */
74      protected Object convertToType(Class type, Object value) throws Throwable {
75          ClassLoader classLoader =
76              Thread.currentThread().getContextClassLoader();
77          if (classLoader != null) {
78              try {
79                  return (classLoader.loadClass(value.toString()));
80              } catch (ClassNotFoundException ex) {
81                  // Don't fail, carry on and try this class's class loader
82                  // (see issue# BEANUTILS-263)
83              }
84          }
85  
86          // Try this class's class loader
87          classLoader = ClassConverter.class.getClassLoader();
88          return (classLoader.loadClass(value.toString()));
89      }
90  
91  }