    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}