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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  }