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 > )
{
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 = ; i < ; 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 = ; 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(, 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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