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1   /*
2    * $Id: ClassUtils.java 471754 2006-11-06 14:55:09Z husted $
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  package org.apache.struts.chain.commands.util;
22  
23  
24  /**
25   * <p>Utility methods to load application classes and create instances.</p>
26   *
27   * @version $Rev: 471754 $ $Date: 2005-11-12 13:01:44 -0500 (Sat, 12 Nov 2005)
28   *          $
29   */
30  public final class ClassUtils {
31      // ---------------------------------------------------------- Static Methods
32  
33      /**
34       * <p>Return the <code>Class</code> object for the specified fully
35       * qualified class name, from this web application's class loader.
36       *
37       * @param className Fully qualified class name
38       * @throws ClassNotFoundException if the specified class cannot be loaded
39       */
40      public static Class getApplicationClass(String className)
41          throws ClassNotFoundException {
42          if (className == null) {
43              throw new NullPointerException(
44                  "getApplicationClass called with null className");
45          }
46  
47          ClassLoader classLoader =
48              Thread.currentThread().getContextClassLoader();
49  
50          if (classLoader == null) {
51              classLoader = ClassUtils.class.getClassLoader();
52          }
53  
54          return (classLoader.loadClass(className));
55      }
56  
57      /**
58       * <p>Return a new instance of the specified fully qualified class name,
59       * after loading the class (if necessary) from this web application's
60       * class loader.</p>
61       *
62       * @param className Fully qualified class name
63       * @throws ClassNotFoundException if the specified class cannot be loaded
64       * @throws IllegalAccessException if this class is not concrete
65       * @throws InstantiationException if this class has no zero-arguments
66       *                                constructor
67       */
68      public static Object getApplicationInstance(String className)
69          throws ClassNotFoundException, IllegalAccessException,
70              InstantiationException {
71          return (getApplicationClass(className).newInstance());
72      }
73  }