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
024 * of the progress of a stream copying operation.  However, it is currently
025 * not used that way within NetComponents for performance reasons.  Rather
026 * the bytesTransferred(long, int) method is called directly rather than
027 * passing an event to bytesTransferred(CopyStreamEvent), saving the creation
028 * of a CopyStreamEvent instance.  Also, the only place where
029 * CopyStreamListener is currently used within NetComponents is in the
030 * static methods of the uninstantiable org.apache.commons.io.Util class, which
031 * would preclude the use of addCopyStreamListener and
032 * removeCopyStreamListener methods.  However, future additions may use the
033 * JavaBean event model, which is why the hooks have been included from the
034 * beginning.
035 *
036 *
037 * @see CopyStreamEvent
038 * @see CopyStreamAdapter
039 * @see Util
040 */
041public interface CopyStreamListener extends EventListener
042{
043    /**
044     * This method is invoked by a CopyStreamEvent source after copying
045     * a block of bytes from a stream.  The CopyStreamEvent will contain
046     * the total number of bytes transferred so far and the number of bytes
047     * transferred in the last write.
048     * @param event The CopyStreamEvent fired by the copying of a block of
049     *              bytes.
050     */
051    void bytesTransferred(CopyStreamEvent event);
052
053
054    /**
055     * This method is not part of the JavaBeans model and is used by the
056     * static methods in the org.apache.commons.io.Util class for efficiency.
057     * It is invoked after a block of bytes to inform the listener of the
058     * transfer.
059     * @param totalBytesTransferred  The total number of bytes transferred
060     *         so far by the copy operation.
061     * @param bytesTransferred  The number of bytes copied by the most recent
062     *          write.
063     * @param streamSize The number of bytes in the stream being copied.
064     *        This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if
065     *        the size is unknown.
066     */
067    void bytesTransferred(long totalBytesTransferred,
068                                 int bytesTransferred,
069                                 long streamSize);
070}