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