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 */
017package org.apache.commons.fileupload2.core;
018
019/**
020 * Receives progress information. May be used to display a progress bar.
021 */
022@FunctionalInterface
023public interface ProgressListener {
024
025    /**
026     * Nop implementation.
027     */
028    ProgressListener NOP = (bytesRead, contentLength, items) -> {
029        // nop
030    };
031
032    /**
033     * Updates the listeners status information.
034     *
035     * @param bytesRead     The total number of bytes, which have been read so far.
036     * @param contentLength The total number of bytes, which are being read. May be -1, if this number is unknown.
037     * @param items         The number of the field, which is currently being read. (0 = no item so far, 1 = first item is being read, ...)
038     */
039    void update(long bytesRead, long contentLength, int items);
040
041}