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 */
017package org.apache.commons.net.io;
018
019import java.util.EventListener;
020
021/**
022 * Accepts {@link CopyStreamEvent}s to track the progress of a stream copying operation. However, it is currently not used that way within Net for performance
023 * reasons. Rather, the bytesTransferred(long, int) method is called directly rather than passing an event to bytesTransferred(CopyStreamEvent), saving the
024 * creation of a CopyStreamEvent instance. Also, the only place where CopyStreamListener is currently used within Net is in the static methods of the
025 * uninstantiable org.apache.commons.io.Util class, which would preclude the use of addCopyStreamListener and removeCopyStreamListener methods. However, future
026 * additions may use the JavaBean event model, which is why the hooks have been included from the beginning.
027 *
028 * @see CopyStreamEvent
029 * @see CopyStreamAdapter
030 * @see Util
031 */
032public interface CopyStreamListener extends EventListener {
033
034    /**
035     * Accepts a source event after copying a block of bytes from a stream. The CopyStreamEvent will contain the total number of bytes transferred so far and
036     * the number of bytes transferred in the last write.
037     *
038     * @param event The CopyStreamEvent fired by the copying of a block of bytes.
039     */
040    void bytesTransferred(CopyStreamEvent event);
041
042    /**
043     * 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
044     * after a block of bytes to inform the listener of the transfer.
045     *
046     * @param totalBytesTransferred The total number of bytes transferred so far by the copy operation.
047     * @param bytesTransferred      The number of bytes copied by the most recent write.
048     * @param streamSize            The number of bytes in the stream being copied. This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is
049     *                              unknown.
050     */
051    void bytesTransferred(long totalBytesTransferred, int bytesTransferred, long streamSize);
052}