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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.fileupload2.core;
    18
    19  /**
    20   * Receives progress information. May be used to display a progress bar.
    21   */
    22  @FunctionalInterface
    23  public interface ProgressListener {
    24
    25      /**
    26       * Nop implementation.
    27       */
    28      ProgressListener NOP = (bytesRead, contentLength, items) -> {
    29          // nop
    30      };
    31
    32      /**
    33       * Updates the listeners status information.
    34       *
    35       * @param bytesRead     The total number of bytes, which have been read so far.
    36       * @param contentLength The total number of bytes, which are being read. May be -1, if this number is unknown.
    37       * @param items         The number of the field, which is currently being read. (0 = no item so far, 1 = first item is being read, ...)
    38       */
    39      void update(long bytesRead, long contentLength, int items);
    40
    41  }