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
022/**
023 * The CopyStreamListener class can accept CopyStreamEvents to keep track of the progress of a stream copying operation. However, it is currently not used that
024 * way within NetComponents for performance reasons. Rather the bytesTransferred(long, int) method is called directly rather than passing an event to
025 * bytesTransferred(CopyStreamEvent), saving the creation of a CopyStreamEvent instance. Also, the only place where CopyStreamListener is currently used within
026 * NetComponents is in the static methods of the uninstantiable org.apache.commons.io.Util class, which would preclude the use of addCopyStreamListener and
027 * removeCopyStreamListener methods. However, future additions may use the JavaBean event model, which is why the hooks have been included from the beginning.
028 *
029 *
030 * @see CopyStreamEvent
031 * @see CopyStreamAdapter
032 * @see Util
033 */
034public interface CopyStreamListener extends EventListener {
035    /**
036     * 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
037     * bytes transferred so far and the number of bytes transferred in the last write.
038     *
039     * @param event The CopyStreamEvent fired by the copying of a block of bytes.
040     */
041    void bytesTransferred(CopyStreamEvent event);
042
043    /**
044     * 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
045     * after a block of bytes to inform the listener of the transfer.
046     *
047     * @param totalBytesTransferred The total number of bytes transferred so far by the copy operation.
048     * @param bytesTransferred      The number of bytes copied by the most recent write.
049     * @param streamSize            The number of bytes in the stream being copied. This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is
050     *                              unknown.
051     */
052    void bytesTransferred(long totalBytesTransferred, int bytesTransferred, long streamSize);
053}