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 * https://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.net.io;
19
20 import org.apache.commons.net.util.ListenerList;
21
22 /**
23 * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners when either of its bytesTransferred() methods are called. Its purpose is to
24 * facilitate the notification of the progress of a copy operation performed by one of the static copyStream() methods in org.apache.commons.io.Util to multiple
25 * listeners. The static copyStream() methods invoke the bytesTransfered(long, int) of a CopyStreamListener for performance reasons and also because multiple
26 * listeners cannot be registered given that the methods are static.
27 *
28 * @see CopyStreamEvent
29 * @see CopyStreamListener
30 * @see Util
31 */
32 public class CopyStreamAdapter implements CopyStreamListener {
33
34 private final ListenerList<CopyStreamListener> listeners;
35
36 /**
37 * Creates a new CopyStreamListener.
38 */
39 public CopyStreamAdapter() {
40 listeners = new ListenerList<>();
41 }
42
43 /**
44 * Adds a CopyStreamListener to receive CopyStreamEvents. Although this method is not declared to be synchronized, it is implemented in a thread safe
45 * manner.
46 *
47 * @param listener The CopyStreamlistener to register.
48 */
49 public void addCopyStreamListener(final CopyStreamListener listener) {
50 listeners.addListener(listener);
51 }
52
53 /**
54 * This method is invoked by a CopyStreamEvent source after copying a block of bytes from a stream. The CopyStreamEvent will contain the total number of
55 * bytes transferred so far and the number of bytes transferred in the last write. The CopyStreamAdapater will relay the event to all of its registered
56 * listeners, listing itself as the source of the event.
57 *
58 * @param event The CopyStreamEvent fired by the copying of a block of bytes.
59 */
60 @Override
61 public void bytesTransferred(final CopyStreamEvent event) {
62 listeners.forEach(listener -> listener.bytesTransferred(event));
63 }
64
65 /**
66 * This method is not part of the JavaBeans model and is used by the static methods in the org.apache.commons.io.Util class for efficiency. It is invoked
67 * after a block of bytes to inform the listener of the transfer. The CopyStreamAdapater will create a CopyStreamEvent from the arguments and relay the
68 * event to all of its registered listeners, listing itself as the source of the event.
69 *
70 * @param totalBytesTransferred The total number of bytes transferred so far by the copy operation.
71 * @param bytesTransferred The number of bytes copied by the most recent write.
72 * @param streamSize The number of bytes in the stream being copied. This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is
73 * unknown.
74 */
75 @Override
76 public void bytesTransferred(final long totalBytesTransferred, final int bytesTransferred, final long streamSize) {
77 listeners.forEach(listener -> listener.bytesTransferred(totalBytesTransferred, bytesTransferred, streamSize));
78 }
79
80 /**
81 * Removes a CopyStreamListener. Although this method is not synchronized, it is implemented in a thread safe manner.
82 *
83 * @param listener The CopyStreamlistener to unregister.
84 */
85 public void removeCopyStreamListener(final CopyStreamListener listener) {
86 listeners.removeListener(listener);
87 }
88 }