content: /*
   * Copyright (C) 2016 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.google.android.exoplayer2.upstream;
  
  /**
   * A listener of data transfer events.
   *
   * <p>A transfer usually progresses through multiple steps:
   *
   * <ol>
   *   <li>Initializing the underlying resource (e.g. opening a HTTP connection). {@link
   *       #onTransferInitializing(DataSource, DataSpec, boolean)} is called before the initialization
   *       starts.
   *   <li>Starting the transfer after successfully initializing the resource. {@link
   *       #onTransferStart(DataSource, DataSpec, boolean)} is called. Note that this only happens if
   *       the initialization was successful.
   *   <li>Transferring data. {@link #onBytesTransferred(DataSource, DataSpec, boolean, int)} is
   *       called frequently during the transfer to indicate progress.
   *   <li>Closing the transfer and the underlying resource. {@link #onTransferEnd(DataSource,
   *       DataSpec, boolean)} is called. Note that each {@link #onTransferStart(DataSource, DataSpec,
   *       boolean)} will have exactly one corresponding call to {@link #onTransferEnd(DataSource,
   *       DataSpec, boolean)}.
   * </ol>
   */
  public interface TransferListener {
  
    /**
     * Called when a transfer is being initialized.
     *
     * @param source The source performing the transfer.
     * @param dataSpec Describes the data for which the transfer is initialized.
     * @param isNetwork Whether the data is transferred through a network.
     */
    void onTransferInitializing(DataSource source, DataSpec dataSpec, boolean isNetwork);
  
    /**
     * Called when a transfer starts.
     *
     * @param source The source performing the transfer.
     * @param dataSpec Describes the data being transferred.
     * @param isNetwork Whether the data is transferred through a network.
     */
    void onTransferStart(DataSource source, DataSpec dataSpec, boolean isNetwork);
  
    /**
     * Called incrementally during a transfer.
     *
     * @param source The source performing the transfer.
     * @param dataSpec Describes the data being transferred.
     * @param isNetwork Whether the data is transferred through a network.
     * @param bytesTransferred The number of bytes transferred since the previous call to this method.
     */
    void onBytesTransferred(
        DataSource source, DataSpec dataSpec, boolean isNetwork, int bytesTransferred);
  
    /**
     * Called when a transfer ends.
     *
     * @param source The source performing the transfer.
     * @param dataSpec Describes the data being transferred.
     * @param isNetwork Whether the data is transferred through a network.
     */
    void onTransferEnd(DataSource source, DataSpec dataSpec, boolean isNetwork);
  }
  