001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.io;
019
020import java.util.EventListener;
021
022import org.apache.commons.net.util.ListenerList;
023
024/**
025 * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners
026 * when either of its bytesTransferred() methods are called.  Its purpose
027 * is to facilitate the notification of the progress of a copy operation
028 * performed by one of the static copyStream() methods in
029 * org.apache.commons.io.Util to multiple listeners.  The static
030 * copyStream() methods invoke the
031 * bytesTransfered(long, int) of a CopyStreamListener for performance
032 * reasons and also because multiple listeners cannot be registered given
033 * that the methods are static.
034 *
035 *
036 * @see CopyStreamEvent
037 * @see CopyStreamListener
038 * @see Util
039 */
040public class CopyStreamAdapter implements CopyStreamListener
041{
042    private final ListenerList internalListeners;
043
044    /**
045     * Creates a new copyStreamAdapter.
046     */
047    public CopyStreamAdapter()
048    {
049        internalListeners = new ListenerList();
050    }
051
052    /**
053     * This method is invoked by a CopyStreamEvent source after copying
054     * a block of bytes from a stream.  The CopyStreamEvent will contain
055     * the total number of bytes transferred so far and the number of bytes
056     * transferred in the last write.  The CopyStreamAdapater will relay
057     * the event to all of its registered listeners, listing itself as the
058     * source of the event.
059     * @param event The CopyStreamEvent fired by the copying of a block of
060     *              bytes.
061     */
062    @Override
063    public void bytesTransferred(final CopyStreamEvent event)
064    {
065        for (final EventListener listener : internalListeners)
066        {
067            ((CopyStreamListener) listener).bytesTransferred(event);
068        }
069    }
070
071    /**
072     * This method is not part of the JavaBeans model and is used by the
073     * static methods in the org.apache.commons.io.Util class for efficiency.
074     * It is invoked after a block of bytes to inform the listener of the
075     * transfer.  The CopyStreamAdapater will create a CopyStreamEvent
076     * from the arguments and relay the event to all of its registered
077     * listeners, listing itself as the source of the event.
078     * @param totalBytesTransferred  The total number of bytes transferred
079     *         so far by the copy operation.
080     * @param bytesTransferred  The number of bytes copied by the most recent
081     *          write.
082     * @param streamSize The number of bytes in the stream being copied.
083     *        This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if
084     *        the size is unknown.
085     */
086    @Override
087    public void bytesTransferred(final long totalBytesTransferred,
088                                 final int bytesTransferred, final long streamSize)
089    {
090        for (final EventListener listener : internalListeners)
091        {
092            ((CopyStreamListener) listener).bytesTransferred(
093                    totalBytesTransferred, bytesTransferred, streamSize);
094        }
095    }
096
097    /**
098     * Registers a CopyStreamListener to receive CopyStreamEvents.
099     * Although this method is not declared to be synchronized, it is
100     * implemented in a thread safe manner.
101     * @param listener  The CopyStreamlistener to register.
102     */
103    public void addCopyStreamListener(final CopyStreamListener listener)
104    {
105        internalListeners.addListener(listener);
106    }
107
108    /**
109     * Unregisters a CopyStreamListener.  Although this method is not
110     * synchronized, it is implemented in a thread safe manner.
111     * @param listener  The CopyStreamlistener to unregister.
112     */
113    public void removeCopyStreamListener(final CopyStreamListener listener)
114    {
115        internalListeners.removeListener(listener);
116    }
117}