    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 *      https://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 org.apache.commons.net.util.ListenerList;
    021
    022/**
    023 * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners when either of its bytesTransferred() methods are called. Its purpose is to
    024 * 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
    025 * listeners. The static copyStream() methods invoke the bytesTransfered(long, int) of a CopyStreamListener for performance reasons and also because multiple
    026 * listeners cannot be registered given that the methods are static.
    027 *
    028 *
    029 * @see CopyStreamEvent
    030 * @see CopyStreamListener
    031 * @see Util
    032 */
    033public class CopyStreamAdapter implements CopyStreamListener {
    034
    035    private final ListenerList<CopyStreamListener> listeners;
    036
    037    /**
    038     * Creates a new copyStreamAdapter.
    039     */
    040    public CopyStreamAdapter() {
    041        listeners = new ListenerList<>();
    042    }
    043
    044    /**
    045     * Adds a CopyStreamListener to receive CopyStreamEvents. Although this method is not declared to be synchronized, it is implemented in a thread safe
    046     * manner.
    047     *
    048     * @param listener The CopyStreamlistener to register.
    049     */
    050    public void addCopyStreamListener(final CopyStreamListener listener) {
    051        listeners.addListener(listener);
    052    }
    053
    054    /**
    055     * 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
    056     * 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
    057     * listeners, listing itself as the source of the event.
    058     *
    059     * @param event The CopyStreamEvent fired by the copying of a block of bytes.
    060     */
    061    @Override
    062    public void bytesTransferred(final CopyStreamEvent event) {
    063        listeners.forEach(listener -> listener.bytesTransferred(event));
    064    }
    065
    066    /**
    067     * 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
    068     * after a block of bytes to inform the listener of the transfer. The CopyStreamAdapater will create a CopyStreamEvent from the arguments and relay the
    069     * event to all of its registered listeners, listing itself as the source of the event.
    070     *
    071     * @param totalBytesTransferred The total number of bytes transferred so far by the copy operation.
    072     * @param bytesTransferred      The number of bytes copied by the most recent write.
    073     * @param streamSize            The number of bytes in the stream being copied. This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is
    074     *                              unknown.
    075     */
    076    @Override
    077    public void bytesTransferred(final long totalBytesTransferred, final int bytesTransferred, final long streamSize) {
    078        listeners.forEach(listener -> listener.bytesTransferred(totalBytesTransferred, bytesTransferred, streamSize));
    079    }
    080
    081    /**
    082     * Removes a CopyStreamListener. Although this method is not synchronized, it is implemented in a thread safe manner.
    083     *
    084     * @param listener The CopyStreamlistener to unregister.
    085     */
    086    public void removeCopyStreamListener(final CopyStreamListener listener) {
    087        listeners.removeListener(listener);
    088    }
    089}