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 when either of its bytesTransferred() methods are called. Its purpose is to
026 * 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
027 * listeners. The static copyStream() methods invoke the bytesTransfered(long, int) of a CopyStreamListener for performance reasons and also because multiple
028 * listeners cannot be registered given that the methods are static.
029 *
030 *
031 * @see CopyStreamEvent
032 * @see CopyStreamListener
033 * @see Util
034 */
035public class CopyStreamAdapter implements CopyStreamListener {
036    private final ListenerList internalListeners;
037
038    /**
039     * Creates a new copyStreamAdapter.
040     */
041    public CopyStreamAdapter() {
042        internalListeners = new ListenerList();
043    }
044
045    /**
046     * Registers a CopyStreamListener to receive CopyStreamEvents. Although this method is not declared to be synchronized, it is implemented in a thread safe
047     * manner.
048     *
049     * @param listener The CopyStreamlistener to register.
050     */
051    public void addCopyStreamListener(final CopyStreamListener listener) {
052        internalListeners.addListener(listener);
053    }
054
055    /**
056     * 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
057     * 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
058     * listeners, listing itself as the source of the event.
059     *
060     * @param event The CopyStreamEvent fired by the copying of a block of bytes.
061     */
062    @Override
063    public void bytesTransferred(final CopyStreamEvent event) {
064        for (final EventListener listener : internalListeners) {
065            ((CopyStreamListener) listener).bytesTransferred(event);
066        }
067    }
068
069    /**
070     * 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
071     * after a block of bytes to inform the listener of the transfer. The CopyStreamAdapater will create a CopyStreamEvent from the arguments and relay the
072     * event to all of its registered listeners, listing itself as the source of the event.
073     *
074     * @param totalBytesTransferred The total number of bytes transferred so far by the copy operation.
075     * @param bytesTransferred      The number of bytes copied by the most recent write.
076     * @param streamSize            The number of bytes in the stream being copied. This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is
077     *                              unknown.
078     */
079    @Override
080    public void bytesTransferred(final long totalBytesTransferred, final int bytesTransferred, final long streamSize) {
081        for (final EventListener listener : internalListeners) {
082            ((CopyStreamListener) listener).bytesTransferred(totalBytesTransferred, bytesTransferred, streamSize);
083        }
084    }
085
086    /**
087     * Unregisters a CopyStreamListener. Although this method is not synchronized, it is implemented in a thread safe manner.
088     *
089     * @param listener The CopyStreamlistener to unregister.
090     */
091    public void removeCopyStreamListener(final CopyStreamListener listener) {
092        internalListeners.removeListener(listener);
093    }
094}