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 * <p>
035 * <p>
036 * @see CopyStreamEvent
037 * @see CopyStreamListener
038 * @see Util
039 * @author <a href="mailto:savarese@apache.org">Daniel F. Savarese</a>
040 * @version $Id: CopyStreamAdapter.java 489397 2006-12-21 16:28:51Z rwinston $
041 */
042public class CopyStreamAdapter implements CopyStreamListener
043{
044    private ListenerList internalListeners;
045
046    /**
047     * Creates a new copyStreamAdapter.
048     */
049    public CopyStreamAdapter()
050    {
051        internalListeners = new ListenerList();
052    }
053
054    /**
055     * This method is invoked by a CopyStreamEvent source after copying
056     * a block of bytes from a stream.  The CopyStreamEvent will contain
057     * the total number of bytes transferred so far and the number of bytes
058     * transferred in the last write.  The CopyStreamAdapater will relay
059     * the event to all of its registered listeners, listing itself as the
060     * source of the event.
061     * @param event The CopyStreamEvent fired by the copying of a block of
062     *              bytes.
063     */
064    public void bytesTransferred(CopyStreamEvent event)
065    {
066        bytesTransferred(event.getTotalBytesTransferred(),
067                         event.getBytesTransferred(),
068                         event.getStreamSize());
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    public void bytesTransferred(long totalBytesTransferred,
087                                 int bytesTransferred, long streamSize)
088    {
089        CopyStreamEvent event;
090
091        event = new CopyStreamEvent(this,
092                                    totalBytesTransferred,
093                                    bytesTransferred,
094                                    streamSize);
095
096        for (EventListener listener : internalListeners)
097        {
098            ((CopyStreamListener) (listener)).bytesTransferred(event);
099        }
100    }
101
102    /**
103     * Registers a CopyStreamListener to receive CopyStreamEvents.
104     * Although this method is not declared to be synchronized, it is
105     * implemented in a thread safe manner.
106     * @param listener  The CopyStreamlistener to register.
107     */
108    public void addCopyStreamListener(CopyStreamListener listener)
109    {
110        internalListeners.addListener(listener);
111    }
112
113    /**
114     * Unregisters a CopyStreamListener.  Although this method is not
115     * synchronized, it is implemented in a thread safe manner.
116     * @param listener  The CopyStreamlistener to unregister.
117     */
118    public void removeCopyStreamListener(CopyStreamListener listener)
119    {
120        internalListeners.removeListener(listener);
121    }
122}