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  • 背水一战 Windows 10 (120) 后台任务: 后台上传任务
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    背水一战 Windows 10 (120) - 后台任务: 后台上传任务



    作者:webabcd


    介绍
    背水一战 Windows 10 之 后台任务

    • 后台上传任务



    示例
    演示 uwp 的后台上传任务
    BackgroundTask/TransferModel.cs

    /*
     * 扩展了 DownloadOperation 和 UploadOperation,用于 MVVM 绑定数据
     */
    
    using System;
    using System.ComponentModel;
    using Windows.Networking.BackgroundTransfer;
    
    namespace Windows10.BackgroundTask
    {
        public class TransferModel : INotifyPropertyChanged
        {
            public DownloadOperation DownloadOperation { get; set; }
            public UploadOperation UploadOperation { get; set; }
    
            public string Source { get; set; }
            public string Destination { get; set; }
    
            private string _progress;
            public string Progress
            {
                get { return _progress; }
                set
                {
                    _progress = value;
                    RaisePropertyChanged("Progress");
                }
            }
    
            public event PropertyChangedEventHandler PropertyChanged;
            protected void RaisePropertyChanged(string name)
            {
                if (PropertyChanged != null)
                {
                    PropertyChanged(this, new PropertyChangedEventArgs(name));
                }
            }
        }
    }

    BackgroundTask/TransferUpload.xaml

    <Page
        x:Class="Windows10.BackgroundTask.TransferUpload"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Windows10.BackgroundTask"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
    
        <Grid Background="Transparent">
            <StackPanel Margin="10 0 10 10">
    
                <ScrollViewer Name="scrollViewer" Height="100" Margin="5">
                    <TextBlock Name="lblMsg" TextWrapping="Wrap" />
                </ScrollViewer>
    
                <Button Name="btnAddUpload" Content="新增一个上传任务(一次请求上传一个文件)" Margin="5" Click="btnAddUpload_Click" />
                <Button Name="btnAddMultiUpload" Content="新增一个上传任务(一次请求上传多个文件)" Margin="5" Click="btnAddMultiUpload_Click" />
                <Button Name="btnCancel" Content="取消所有上传任务" Margin="5" Click="btnCancel_Click" />
    
                <ListView Name="listView" Height="286" Padding="5">
                    <ListView.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Margin="0 5" Background="Blue">
                                <TextBlock Text="{Binding Source}" Margin="5" />
                                <TextBlock Text="{Binding Destination}" Margin="5" />
                                <TextBlock Text="{Binding Progress}" Margin="5" />
                            </StackPanel>
                        </DataTemplate>
                    </ListView.ItemTemplate>
                </ListView>
    
            </StackPanel>
        </Grid>
    </Page>

    BackgroundTask/TransferUpload.xaml.cs

    /*
     * 演示 uwp 的后台上传任务
     * 
     * BackgroundUploader - 后台上传任务管理器
     *     CreateUpload(Uri uri, IStorageFile sourceFile) - 创建一个上传任务,返回 UploadOperation 对象
     *     CreateUploadFromStreamAsync(Uri uri, IInputStream sourceStream) - 以流的方式创建一个上传任务
     *     CreateUploadAsync(Uri uri, IEnumerable<BackgroundTransferContentPart> parts) - 创建一个包含多个上传文件的上传任务
     *     SetRequestHeader(string headerName, string headerValue) - 设置 http 请求头
     *     Method - 用于上传的 http method(默认 post)
     *     static GetCurrentUploadsAsync() - 获取当前 app 的未与组关联的所有上传任务
     *     CostPolicy - 上传的成本策略,BackgroundTransferCostPolicy 枚举
     *         Default - 不允许在高成本(比如 4G)网络上传输
     *         UnrestrictedOnly - 允许在高成本(比如 4G)网络上传输
     *         Always - 无论如何均可传输,即使在漫游时
     *     ServerCredential - 与服务端通信时的凭据
     *     ProxyCredential - 使用代理时的身份凭据
     *     SuccessToastNotification, SuccessTileNotification, FailureToastNotification, FailureTileNotification - 上传任务成功或失败后的 toast 或 tile 通知
     *     static GetCurrentUploadsForTransferGroupAsync(BackgroundTransferGroup group) - 获取指定组的所有上传任务
     *     TransferGroup - 设置或获取分组对象(BackgroundTransferGroup 类型)
     *     BackgroundUploader(BackgroundTransferCompletionGroup completionGroup) - 通过指定的 BackgroundTransferCompletionGroup 对象实例化 BackgroundUploader 对象
     *     CompletionGroup - 获取关联的 BackgroundTransferCompletionGroup 对象
     *     
     * UploadOperation - 上传任务对象
     *     Guid - 获取此上传任务的标识
     *     CostPolicy - 上传的成本策略,BackgroundTransferCostPolicy 枚举
     *     RequestedUri - 上传任务所请求的服务端地址
     *     SourceFile - 需要上传的文件,如果是一次上传多个文件则此属性为 null
     *     Method - 获取用于上传的 http method(get, post 之类的)
     *     GetResponseInformation() - 上传完成后获取到的服务端响应信息,返回 ResponseInformation 对象
     *         ActualUri - 上传服务的真实 URI
     *         Headers - 服务端响应的 HTTP 头
     *         StatusCode - 服务端响应的状态码
     *     StartAsync() - 新增一个上传任务,返回 IAsyncOperationWithProgress<UploadOperation, UploadOperation> 对象
     *     AttachAsync() - 监视已存在的上传任务,返回 IAsyncOperationWithProgress<UploadOperation, UploadOperation> 对象
     *     Progress - 获取上传进度,返回 BackgroundUploadProgress 对象
     *     Priority - 上传的优先级,BackgroundTransferPriority 枚举
     *         Default 或 High
     *     TransferGroup - 获取此上传任务的分组对象(BackgroundTransferGroup 类型)
     *     
     * BackgroundUploadProgress - 后台上传任务的上传进度对象
     *     BytesSent - 已上传的字节数
     *     TotalBytesToSend - 总共需要上传的字节数
     *     BytesReceived - 已下载的字节数
     *     TotalBytesToReceive - 总共需要下载的字节数,未知则为 0 
     *     Status - 上传状态,BackgroundTransferStatus 枚举
     *         Idle, Running, PausedByApplication, PausedCostedNetwork, PausedNoNetwork, Completed, Canceled, Error
     *     HasResponseChanged - 服务端响应了则为 true
     *     HasRestarted - 当上传连接断掉后,系统会重新上传,此种情况则为 true
     *     
     * BackgroundTransferGroup - 后台上传任务的分组对象
     *     static BackgroundTransferGroup CreateGroup(string name) - 创建指定分组标识的 BackgroundTransferGroup 对象
     *     Name - 分组标识(只读)
     *     TransferBehavior - 组内上传任务的执行方式,BackgroundTransferBehavior 枚举
     *         Parallel - 并行
     *         Serialized - 串行
     * 
     * BackgroundTransferCompletionGroup - 分组对象(用于实现“组任务全部完成后触发后台任务”)
     *     Enable() - 启用“组任务全部完成后触发后台任务”的功能
     *     IsEnabled - 是否启用了“组任务全部完成后触发后台任务”的功能(只读)
     *     Trigger - “组任务全部完成后触发后台任务”的触发器
     *     
     * BackgroundTransferContentPart - 当一次上传多个文件时,将每个需要上传的文件构造成一个 BackgroundTransferContentPart 对象
     *     BackgroundTransferContentPart(string name, string fileName) - 通过一个标识和文件名称实例化 BackgroundTransferContentPart 对象
     *     SetFile(IStorageFile value) - 指定需要上传的文件
     *     
     * 
     * 注:关于上传任务的“任务分组,并行或串行执行,组完成后通知”和“任务分组,组完成后触发后台任务”的实现方式与下载任务是一样的,请参见下载任务的相关演示示例(TransferGroup.xaml.cs 和 TransferBackground.xaml.cs)
     */
    
    using System;
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Linq;
    using System.Threading;
    using System.Threading.Tasks;
    using Windows.Data.Xml.Dom;
    using Windows.Networking.BackgroundTransfer;
    using Windows.Storage;
    using Windows.UI.Notifications;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    using Windows.Web;
    
    namespace Windows10.BackgroundTask
    {
        public sealed partial class TransferUpload : Page
        {
            // 上传任务的集合
            private ObservableCollection<TransferModel> _transfers = new ObservableCollection<TransferModel>();
    
            // 所有上传任务的关联的 CancellationTokenSource 对象
            private CancellationTokenSource _cancelToken = new CancellationTokenSource();
    
            public TransferUpload()
            {
                this.InitializeComponent();
    
                Init();
            }
    
            private async void Init()
            {
                listView.ItemsSource = _transfers;
    
                // 加载全部上传任务
                await LoadUploadAsync();
            }
    
            // 加载全部上传任务
            private async Task LoadUploadAsync()
            {
                IReadOnlyList<UploadOperation> uploads = null;
                try
                {
                    // 获取所有后台上传任务
                    uploads = await BackgroundUploader.GetCurrentUploadsAsync();
                }
                catch (Exception ex)
                {
                    WriteLine(ex.ToString());
                    return;
                }
    
                if (uploads.Count > 0)
                {
                    List<Task> tasks = new List<Task>();
                    foreach (UploadOperation upload in uploads)
                    {
                        // 监视指定的后台上传任务
                        tasks.Add(HandleUploadAsync(upload, false));
                    }
    
                    await Task.WhenAll(tasks);
                }
            }
    
            // 新增一个上传任务(一次请求上传一个文件)
            private async void btnAddUpload_Click(object sender, RoutedEventArgs e)
            {
                // 上传服务的地址
                Uri serverUri = new Uri("http://localhost:44914/api/Upload", UriKind.Absolute);
    
                StorageFile sourceFile;
                try
                {
                    // 需要上传的文件
                    sourceFile = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/hololens.jpg", UriKind.Absolute));
                }
                catch (Exception ex)
                {
                    WriteLine(ex.ToString());
                    return;
                }
    
                // 实例化 BackgroundUploader,并设置 http header
                BackgroundUploader backgroundUploader = new BackgroundUploader();
                backgroundUploader.SetRequestHeader("Filename", "hololens.jpg");
    
                // 任务成功后弹出指定的 toast 通知(类似的还有 SuccessTileNotification, FailureToastNotification, FailureTileNotification)
                backgroundUploader.SuccessToastNotification = GetToastNotification();
    
                // 创建一个后台上传任务,此任务包含一个上传文件
                UploadOperation upload = backgroundUploader.CreateUpload(serverUri, sourceFile);
    
                // 以流的方式创建一个后台上传任务
                // await backgroundUploader.CreateUploadFromStreamAsync(Uri uri, IInputStream sourceStream);
    
                // 处理并监视指定的后台上传任务
                await HandleUploadAsync(upload, true);
            }
    
            // 新增一个上传任务(一次请求上传多个文件)
            private async void btnAddMultiUpload_Click(object sender, RoutedEventArgs e)
            {
                // 上传服务的地址
                Uri serverUri = new Uri("http://localhost:44914/api/Upload", UriKind.Absolute);
    
                // 需要上传的文件源集合
                List<StorageFile> sourceFiles = new List<StorageFile>();
                for (int i = 0; i < 3; i++)
                {
                    StorageFile sourceFile = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/hololens.jpg", UriKind.Absolute));
                    sourceFiles.Add(sourceFile);
                }
    
                // 构造需要上传 BackgroundTransferContentPart 集合
                List<BackgroundTransferContentPart> contentParts = new List<BackgroundTransferContentPart>();
                for (int i = 0; i < sourceFiles.Count; i++)
                {
                    BackgroundTransferContentPart contentPart = new BackgroundTransferContentPart("File" + i, sourceFiles[i].Name);
                    contentPart.SetFile(sourceFiles[i]);
                    contentParts.Add(contentPart);
                }
                
                BackgroundUploader backgroundUploader = new BackgroundUploader();
    
                // 任务成功后弹出指定的 toast 通知(类似的还有 SuccessTileNotification, FailureToastNotification, FailureTileNotification)
                backgroundUploader.SuccessToastNotification = GetToastNotification();
    
                // 创建一个后台上传任务,此任务包含多个上传文件
                UploadOperation upload = await backgroundUploader.CreateUploadAsync(serverUri, contentParts);
    
                // 处理并监视指定的后台上传任务
                await HandleUploadAsync(upload, true);
            }
    
            /// <summary>
            /// 处理并监视指定的后台上传任务
            /// </summary>
            /// <param name="upload">后台上传任务</param>
            /// <param name="isNew">是否是新增的任务</param>
            private async Task HandleUploadAsync(UploadOperation upload, bool isNew)
            {
                try
                {
                    // 将 UploadOperation 附加到 TransferModel,以便上传进度可通知
                    TransferModel transfer = new TransferModel();
                    transfer.UploadOperation = upload;
                    transfer.Source = "多个文件";
                    transfer.Destination = upload.RequestedUri.ToString();
                    transfer.Progress = upload.Progress.Status.ToString() + "0 / 0";
    
                    _transfers.Add(transfer);
    
                    WriteLine("Task Count: " + _transfers.Count.ToString());
    
                    // 当上传进度发生变化时的回调函数
                    Progress<UploadOperation> progressCallback = new Progress<UploadOperation>(UploadProgress);
    
                    if (isNew)
                        await upload.StartAsync().AsTask(_cancelToken.Token, progressCallback); // 启动一个后台上传任务
                    else
                        await upload.AttachAsync().AsTask(_cancelToken.Token, progressCallback); // 监视已存在的后台上传任务
    
                    // 上传完成后获取服务端的响应信息
                    ResponseInformation response = upload.GetResponseInformation();
                    WriteLine("Completed: " + response.ActualUri + ", HttpStatusCode: " + response.StatusCode.ToString());
                }
                catch (TaskCanceledException) // 调用 CancellationTokenSource.Cancel() 后会抛出此异常
                {
                    WriteLine("Canceled: " + upload.Guid);
                }
                catch (Exception ex)
                {
                    // 将异常转换为 WebErrorStatus 枚举,如果获取到的是 WebErrorStatus.Unknown 则说明此次异常不是涉及 web 的异常
                    WebErrorStatus error = BackgroundTransferError.GetStatus(ex.HResult);
    
                    WriteLine(ex.ToString());
                }
                finally
                {
                    _transfers.Remove(_transfers.First(p => p.UploadOperation == upload));
                }
            }
    
            // 进度发生变化时,更新 TransferModel 的 Progress
            private void UploadProgress(UploadOperation upload)
            {
                TransferModel transfer = _transfers.First(p => p.UploadOperation == upload);
                transfer.Progress = upload.Progress.Status.ToString() + ": " + upload.Progress.BytesSent.ToString("#,0") + " / " + upload.Progress.TotalBytesToSend.ToString("#,0");
            }
    
            // 取消全部后台上传任务
            private void btnCancel_Click(object sender, RoutedEventArgs e)
            {
                _cancelToken.Cancel();
                _cancelToken.Dispose();
    
                _cancelToken = new CancellationTokenSource();
            }
    
            // 向 lblMsg 中追加一行文本
            private void WriteLine(string message)
            {
                lblMsg.Text += message;
                lblMsg.Text += Environment.NewLine;
    
                scrollViewer.ChangeView(0, scrollViewer.ScrollableHeight, 1f);
            }
    
            // 构造指定的 toast 通知
            private ToastNotification GetToastNotification()
            {
                string toastXml = $@"
                    <toast activationType='foreground'>
                        <visual>
                            <binding template='ToastGeneric'>
                                <text>toast - title</text>
                                <text>上传任务成功完成</text>
                            </binding>
                        </visual>
                    </toast>";
                
                XmlDocument toastDoc = new XmlDocument();
                toastDoc.LoadXml(toastXml);
    
                return new ToastNotification(toastDoc);
            }
        }
    }



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    [源码下载]

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  • 原文:https://www.cnblogs.com/webabcd/p/9211766.html
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