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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  
18  package org.apache.commons.proxy.provider;
19  
20  import org.apache.commons.proxy.ObjectProvider;
21  import org.apache.commons.proxy.ProxyUtils;
22  import org.apache.commons.proxy.exception.ObjectProviderException;
23  
24  import java.lang.reflect.InvocationTargetException;
25  import java.lang.reflect.Method;
26  
27  /**
28   * Merely calls <code>clone()</code> (reflectively) on the given {@link Cloneable} object.
29   *
30   * @author James Carman
31   * @since 1.0
32   */
33  public class CloningProvider implements ObjectProvider
34  {
35      private final Cloneable cloneable;
36      private Method cloneMethod;
37  
38      /**
39       * Constructs a provider which returns clone copies of the specified {@link Cloneable}
40       * object.
41       * @param cloneable the object to clone
42       */
43      public CloningProvider( Cloneable cloneable )
44      {
45          this.cloneable = cloneable;
46      }
47  
48      private synchronized Method getCloneMethod()
49      {
50          if( cloneMethod == null )
51          {
52              try
53              {
54                  cloneMethod = cloneable.getClass().getMethod( "clone", ProxyUtils.EMPTY_ARGUMENT_TYPES );
55              }
56              catch( NoSuchMethodException e )
57              {
58                  throw new ObjectProviderException(
59                          "Class " + cloneable.getClass().getName() + " does not have a public clone() method." );
60              }
61          }
62          return cloneMethod;
63      }
64  
65      public Object getObject()
66      {
67          try
68          {
69              return getCloneMethod().invoke( cloneable, ProxyUtils.EMPTY_ARGUMENTS );
70          }
71          catch( IllegalAccessException e )
72          {
73              throw new ObjectProviderException(
74                      "Class " + cloneable.getClass().getName() + " does not have a public clone() method.", e );
75          }
76          catch( InvocationTargetException e )
77          {
78              throw new ObjectProviderException(
79                      "Attempt to clone object of type " + cloneable.getClass().getName() + " threw an exception.", e );
80          }
81      }
82  
83  }