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1   /*
2    * Copyright 2001-2005 The Apache Software Foundation
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.net.io;
17  
18  import java.util.Enumeration;
19  import org.apache.commons.net.util.ListenerList;
20  
21  /**
22   * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners
23   * when either of its bytesTransferred() methods are called.  Its purpose
24   * is to facilitate the notification of the progress of a copy operation
25   * performed by one of the static copyStream() methods in
26   * org.apache.commons.io.Util to multiple listeners.  The static
27   * copyStream() methods invoke the
28   * bytesTransfered(long, int) of a CopyStreamListener for performance
29   * reasons and also because multiple listeners cannot be registered given
30   * that the methods are static.
31   * <p>
32   * <p>
33   * @see CopyStreamEvent
34   * @see CopyStreamListener
35   * @see Util
36   * @author <a href="mailto:savarese@apache.org">Daniel F. Savarese</a>
37   * @version $Id: CopyStreamAdapter.java 165675 2005-05-02 20:09:55Z rwinston $
38   */
39  public class CopyStreamAdapter implements CopyStreamListener
40  {
41      private ListenerList internalListeners;
42  
43      /**
44       * Creates a new copyStreamAdapter.
45       */
46      public CopyStreamAdapter()
47      {
48          internalListeners = new ListenerList();
49      }
50  
51      /**
52       * This method is invoked by a CopyStreamEvent source after copying
53       * a block of bytes from a stream.  The CopyStreamEvent will contain
54       * the total number of bytes transferred so far and the number of bytes
55       * transferred in the last write.  The CopyStreamAdapater will relay
56       * the event to all of its registered listeners, listing itself as the
57       * source of the event.
58       * @param event The CopyStreamEvent fired by the copying of a block of
59       *              bytes.
60       */
61      public void bytesTransferred(CopyStreamEvent event)
62      {
63          bytesTransferred(event.getTotalBytesTransferred(),
64                           event.getBytesTransferred(),
65                           event.getStreamSize());
66      }
67  
68      /**
69       * This method is not part of the JavaBeans model and is used by the
70       * static methods in the org.apache.commons.io.Util class for efficiency.
71       * It is invoked after a block of bytes to inform the listener of the
72       * transfer.  The CopyStreamAdapater will create a CopyStreamEvent
73       * from the arguments and relay the event to all of its registered
74       * listeners, listing itself as the source of the event.
75       * @param totalBytesTransferred  The total number of bytes transferred
76       *         so far by the copy operation.
77       * @param bytesTransferred  The number of bytes copied by the most recent
78       *          write.
79       * @param streamSize The number of bytes in the stream being copied.
80       *        This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if
81       *        the size is unknown.
82       */
83      public void bytesTransferred(long totalBytesTransferred,
84                                   int bytesTransferred, long streamSize)
85      {
86          Enumeration listeners;
87          CopyStreamEvent event;
88  
89          listeners = internalListeners.getListeners();
90  
91          event = new CopyStreamEvent(this,
92                                      totalBytesTransferred,
93                                      bytesTransferred,
94                                      streamSize);
95  
96          while (listeners.hasMoreElements())
97          {
98              ((CopyStreamListener) (listeners.nextElement())).
99                  bytesTransferred(event);
100         }
101     }
102 
103     /**
104      * Registers a CopyStreamListener to receive CopyStreamEvents.
105      * Although this method is not declared to be synchronized, it is
106      * implemented in a thread safe manner.
107      * @param listener  The CopyStreamlistener to register.
108      */
109     public void addCopyStreamListener(CopyStreamListener listener)
110     {
111         internalListeners.addListener(listener);
112     }
113 
114     /**
115      * Unregisters a CopyStreamListener.  Although this method is not
116      * synchronized, it is implemented in a thread safe manner.
117      * @param listener  The CopyStreamlistener to unregister.
118      */
119     public void removeCopyStreamListener(CopyStreamListener listener)
120     {
121         internalListeners.removeListener(listener);
122     }
123 }