C# BackgroundDownloader.CreateDownload方法代码示例

        public static async Task<Episode> DownloadPodcastEpisodeAsync(Episode episode, Action<DownloadOperation> callback, Action errorCallback = null)
        {
            var appFolder = await KnownFolders.MusicLibrary.CreateFolderAsync("PodcastR", CreationCollisionOption.OpenIfExists);
            var podcastFolder = await appFolder.CreateFolderAsync(episode.Podcast.Name, CreationCollisionOption.OpenIfExists);
            try
            {
                var uri = new Uri(episode.WebPath);
                var extension = uri.AbsolutePath.GetExtension();
                var fileName = (episode.Name + extension).RemoveIllegalPathChars().Replace(":", "");
                var episodeFile = await podcastFolder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
                var backgroundDownloader = new BackgroundDownloader();
                var downloadOperation = backgroundDownloader.CreateDownload(uri, episodeFile);
                var progress = new Progress<DownloadOperation>(callback);
                downloads.Add(episode, downloadOperation);
                var cts = new CancellationTokenSource();
                cancellationTokenSources.Add(episode, cts);

                await downloadOperation.StartAsync().AsTask(cts.Token, progress);

                downloads.Remove(episode);
                cancellationTokenSources.Remove(episode);
                episode.IsLocal = true;
                episode.WebPath = episodeFile.Path;
                return episode;
            }
            catch
            {
                if (errorCallback != null)
                    errorCallback();
                return episode;
            }
        }

        /// <summary>
        /// download a file 
        /// </summary>
        /// <param name="fileUrl">fileUrl</param>
        /// <param name="destinationFile">file's destination</param>
        /// <param name="downloadProgress">a action that can show the download progress</param>
        /// <param name="priority">background transfer priority </param>
        /// <param name="requestUnconstrainedDownload"></param>
        /// <returns></returns>
        public static async Task DownLoadSingleFileAsync(string fileUrl, IStorageFile destinationFile, Action<DownloadOperation> downloadProgress =null
        , BackgroundTransferPriority priority = BackgroundTransferPriority.Default, bool requestUnconstrainedDownload = false)
        {
            Uri source;
            if (!Uri.TryCreate(fileUrl, UriKind.Absolute, out source))
            {
                // Logger.Info("File Url:" + fileUrl + "is not valid URIs");
                Debug.WriteLine("File Url:" + fileUrl + "is not valid URIs");
                return;
            }
            BackgroundDownloader downloader = new BackgroundDownloader();
            DownloadOperation download = downloader.CreateDownload(source, destinationFile);
            download.Priority = priority;

            Debug.WriteLine(String.Format(CultureInfo.CurrentCulture, "Downloading {0} to {1} with {2} priority, {3}",
                source.AbsoluteUri, destinationFile.Name, priority, download.Guid));

            if (!requestUnconstrainedDownload)
            {
                // Attach progress and completion handlers.
                await HandleDownloadAsync(download, true, downloadProgress);
                return;

            }
        }

        private async void getInfo()
        {
            StorageFile myDB;
            try
            {
                string address = @"http://artmordent.ru/cheataxi/multiplylines.cr";
                StorageFile tempFile2 = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFileAsync("info", CreationCollisionOption.ReplaceExisting);
                BackgroundDownloader manager2 = new BackgroundDownloader();
                var operation = manager2.CreateDownload(new Uri(address), tempFile2);
                IProgress<DownloadOperation> progressH = new Progress<DownloadOperation>((p) => { });
                await operation.StartAsync().AsTask(progressH);                
                myDB = await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync("info");
                
                // Read the data
                var alldata = await Windows.Storage.FileIO.ReadLinesAsync(myDB);
                string[] datalines = new string[alldata.Count];
                Int32 ko = 0;
                foreach (var line in alldata)
                {
                    datalines[ko] = line.ToString();
                    ko++;
                    infoBlockMain.Text += line.ToString() + "\r\n";
                }
                
                await myDB.DeleteAsync();


            }
            catch (Exception ex)
            {
                MessageDialog dialog = new MessageDialog("Ошибка загрузки информации. Проверьте ваше соединение или попробуйте позже.", "Ошибка загрузки");
            }
        }

        //string imagerySet = MapType.Aerial.ToString();

        public async Task<WriteableBitmap> RequestImage(Geopoint point)
        {
            
            if (geo == null)
            {
                geo = new Geolocator();
            }
            Geoposition pos = await geo.GetGeopositionAsync();
            //Geopoint point = pos.Coordinate.Point;

            myMap.Center = new Location(point.Position.Latitude, point.Position.Longitude);
            myMap.ZoomLevel = 2;
            myMap.Width = 100;
            this.myMap.Height = 100;
            string url = String.Format("http://dev.virtualearth.net/REST/v1/Imagery/Map/{0}/{1},{2}/{3}" +
                                  "?mapSize={4},{5}&key={6}",
                               //imagerySet,
                               this.myMap.Center.Latitude,
                               this.myMap.Center.Longitude,
                               Math.Floor(this.myMap.ZoomLevel),
                               this.myMap.Width,
                               this.myMap.Height,
                               apiKey);


            var backgroundDownloader = new BackgroundDownloader();
            var file = await ApplicationData.Current.TemporaryFolder.CreateFileAsync("tempmapimage.jpg",
                CreationCollisionOption.ReplaceExisting);
            var downloadOperation = backgroundDownloader.CreateDownload(new Uri(url), file);

            await downloadOperation.StartAsync();
            return await BitmapFactory.New(1, 1).FromStream(await file.OpenReadAsync(),
                Windows.Graphics.Imaging.BitmapPixelFormat.Unknown);
        }

		public static async Task<bool> Download(Revista rev, Func<IStorageFile, Task> onSucess, Action<string> callBack, Action<double> progressHandler)
		{
			if(!HaveInternetConnection())
			{
				callBack("Sem conexão à Internet");
				return false; 
			}

			BackgroundDownloader bg = new BackgroundDownloader();

			var folder = await ApplicationData.Current.LocalFolder.CreateFolderAsync(RevistaControllerWrapper.FolderName, CreationCollisionOption.OpenIfExists);
			var file = await folder.CreateFileAsync(RevistaControllerWrapper.GetPdfName(rev), CreationCollisionOption.ReplaceExisting);

			DownloadHelper down = new DownloadHelper(); ;
			try
			{
				var d = bg.CreateDownload(RevistaController.Instance.GetDownloadFile(rev), file);

				await down.HandleDownloadAsync(d, true, onSucess, callBack, progressHandler);
			}
			catch
			{
				return false;
			}
			return true ;
		}

		private async void Button_Click(object sender, RoutedEventArgs e)
		{
			var source = new Uri("http://download.thinkbroadband.com/5MB.zip", UriKind.Absolute);
			var destination = await KnownFolders
				.PicturesLibrary
				.CreateFileAsync("5MB.zip", CreationCollisionOption.GenerateUniqueName);

			var downloader = new BackgroundDownloader();

			// Toast notification para sucesso
			var successToastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText01);
			successToastXml.GetElementsByTagName("text").Item(0).InnerText =
				"Download Concluído.";
			var successToast = new ToastNotification(successToastXml);
			downloader.SuccessToastNotification = successToast;

			// Toast notification para falha
			var failureToastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText01);
			failureToastXml.GetElementsByTagName("text").Item(0).InnerText =
				"Falha no download.";
			var failureToast = new ToastNotification(failureToastXml);
			downloader.FailureToastNotification = failureToast;

			var downloadOperation = downloader.CreateDownload(source, destination);
			downloadOperation.Priority = BackgroundTransferPriority.High;

			var progressCallback = new Progress<DownloadOperation>(DownloadProgress);
			await downloadOperation.StartAsync().AsTask(new CancellationToken(), progressCallback);
			;
		}

        private static async Task<StorageFile> SaveFileFromUriAsync(Uri fileUri, string localFileName, string localPath = "Images", NameCollisionOption collisionOption = NameCollisionOption.ReplaceExisting)
        {
            if (localFileName.StartsWith("/"))
                localFileName = localFileName.Substring(1);

            localFileName = Path.GetFileName(localFileName);
            
            var destinationFolder = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFolderAsync(localPath, CreationCollisionOption.OpenIfExists);

            var outFile = await destinationFolder.CreateFileAsync(localFileName, CreationCollisionOption.OpenIfExists);
            if((await outFile.GetBasicPropertiesAsync()).Size == 0)
            {
                BackgroundDownloader backgroundDownloader = new BackgroundDownloader();
                var download = backgroundDownloader.CreateDownload(fileUri, outFile);
                try
                {
                    download.CostPolicy = BackgroundTransferCostPolicy.Always;
                    var downloadTask = download.StartAsync();
                    await downloadTask;
                }
                catch
                {
                }

            }
            return outFile;
        }

        private async void StartDownload(BackgroundTransferPriority priority,bool requestUnconstrainedDownload,string downloadLink,string destination) {
            // Validating the URI is required since it was received from an untrusted source (user input).
            // The URI is validated by calling Uri.TryCreate() that will return 'false' for strings that are not valid URIs.
            // Note that when enabling the text box users may provide URIs to machines on the intrAnet that require
            // the "Home or Work Networking" capability.
            Uri source;
            if(!Uri.TryCreate(downloadLink,UriKind.Absolute,out source)) {
                Debug.WriteLine("Invalid URI.");
                return;
            }

            if(string.IsNullOrWhiteSpace(destination)) {
                Debug.WriteLine("A local file name is required.");
                return;
            }

            StorageFile destinationFile;
            try {
                destinationFile = await KnownFolders.PicturesLibrary.CreateFileAsync(
                    destination,
                    CreationCollisionOption.GenerateUniqueName);
            }
            catch(FileNotFoundException ex) {
                Debug.WriteLine("Error while creating file: " + ex.Message );
                return;
            }

            BackgroundDownloader downloader = new BackgroundDownloader();
            DownloadOperation download = downloader.CreateDownload(source,destinationFile);

            Debug.WriteLine(String.Format(CultureInfo.CurrentCulture,"Downloading {0} to {1} with {2} priority, {3}",
                source.AbsoluteUri,destinationFile.Name,priority,download.Guid));

            download.Priority = priority;

            if(!requestUnconstrainedDownload) {
                // Attach progress and completion handlers.
                await HandleDownloadAsync(download,true);
                return;
            }

            List<DownloadOperation> requestOperations = new List<DownloadOperation>();
            requestOperations.Add(download);

            // If the app isn't actively being used, at some point the system may slow down or pause long running
            // downloads. The purpose of this behavior is to increase the device's battery life.
            // By requesting unconstrained downloads, the app can request the system to not suspend any of the
            // downloads in the list for power saving reasons.
            // Use this API with caution since it not only may reduce battery life, but it may show a prompt to
            // the user.
            UnconstrainedTransferRequestResult result = await BackgroundDownloader.RequestUnconstrainedDownloadsAsync(requestOperations);

            Debug.WriteLine(String.Format(CultureInfo.CurrentCulture,"Request for unconstrained downloads has been {0}",
                (result.IsUnconstrained ? "granted" : "denied")));

            await HandleDownloadAsync(download,true);
        }

        public async void download(String url, Folder folder)
        {

            var uri = new Uri(url);
            var downloader = new BackgroundDownloader();
            StorageFile file = await folder.CreateFileAsync("100MB.zip",
                CreationCollisionOption.ReplaceExisting);
            DownloadOperation download = downloader.CreateDownload(uri, file);
            download.StartAsync();
        }

 private async void DownloadClick(object sender, RoutedEventArgs e)
 {
     const string fileLocation
      = "http://www.vulcanlab.net/download/Release.rar";
     var uri = new Uri(fileLocation);
     var downloader = new BackgroundDownloader();
     StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("100MB.zip",
         CreationCollisionOption.ReplaceExisting);
     DownloadOperation download = downloader.CreateDownload(uri, file);
     await StartDownloadAsync(download);
 }

        public async Task<StorageFile> DownloadFileAsync(
            string appFolderName,
            string folderName,
            string fileName,
            string fileUrl,
            Action<DownloadOperation> callback,
            Action<Exception> errorCallback = null)
        {
            var appFolder = await KnownFolders.MusicLibrary.CreateFolderAsync(appFolderName, CreationCollisionOption.OpenIfExists);
            var podcastFolder = await appFolder.CreateFolderAsync(folderName, CreationCollisionOption.OpenIfExists);
            var uri = new Uri(fileUrl);
            var extension = uri.AbsolutePath.GetExtension();
            var filename = (fileName + extension).RemoveIllegalPathChars();

            try
            {
                var file = await podcastFolder.CreateFileAsync(filename, CreationCollisionOption.FailIfExists);
                var backgroundDownloader = new BackgroundDownloader();
                var downloadOperation = backgroundDownloader.CreateDownload(uri, file);

                var progress = new Progress<DownloadOperation>(callback);
                downloads.Add(fileUrl, downloadOperation);

                var cts = new CancellationTokenSource();
                cancellationTokenSources.Add(fileUrl, cts);

                await downloadOperation.StartAsync().AsTask(cts.Token, progress);

                downloads.Remove(fileUrl);
                cancellationTokenSources.Remove(fileUrl);
                return file;
            }
            catch (NullReferenceException ex)
            {
                if (errorCallback != null)
                    errorCallback(ex);
                return null;
            }
            catch (Exception)
            {
                try
                {
                    var file = await podcastFolder.GetFileAsync(filename);
                    return file;
                }
                catch (Exception ex)
                {
                    if (errorCallback != null)
                        errorCallback(ex);
                    return null;
                }
            }

        }

        public async Task<string> GetAsync(string request)
        {
            var backgroundDownloader = new BackgroundDownloader();
            var temporaryFile = await ApplicationData.Current.LocalFolder.CreateFileAsync(Utils.TemporaryFile, CreationCollisionOption.OpenIfExists);
            var downloader = backgroundDownloader.CreateDownload(
                new Uri(request),
                temporaryFile);
            await downloader.StartAsync();

            var file = await ApplicationData.Current.LocalFolder.CreateFileAsync(Utils.TemporaryFile, CreationCollisionOption.OpenIfExists);
            return await FileIO.ReadTextAsync(file);
        }

        private async void StartDownload(BackgroundTransferPriority priority,bool requestUnconstrainedDownload,string url,string fileNameField) {
            Uri source;
            if(!Uri.TryCreate(url.Trim(),UriKind.Absolute,out source)) {
                //rootPage.NotifyUser("Invalid URI.",NotifyType.ErrorMessage);
                return;
            }

            string destination = fileNameField.Trim() + ".zip";

            if(string.IsNullOrWhiteSpace(destination)) {
                destination = fileNameField.Trim();
            }

            StorageFile destinationFile;
            try {
                destinationFile = await KnownFolders.VideosLibrary.CreateFileAsync(
                    destination,
                    CreationCollisionOption.GenerateUniqueName);
            }
            catch {
                return;
            }

            BackgroundDownloader downloader = new BackgroundDownloader();
            DownloadOperation download = downloader.CreateDownload(source,destinationFile);

            //Log(String.Format(CultureInfo.CurrentCulture,"Downloading {0} to {1} with {2} priority, {3}",
            //    source.AbsoluteUri,destinationFile.Name,priority,download.Guid));

            download.Priority = priority;

            if(!requestUnconstrainedDownload) {
                // Attach progress and completion handlers.
                await HandleDownloadAsync(download,true);
                return;
            }

            List<DownloadOperation> requestOperations = new List<DownloadOperation>();
            requestOperations.Add(download);

            // If the app isn't actively being used, at some point the system may slow down or pause long running
            // downloads. The purpose of this behavior is to increase the device's battery life.
            // By requesting unconstrained downloads, the app can request the system to not suspend any of the
            // downloads in the list for power saving reasons.
            // Use this API with caution since it not only may reduce battery life, but it may show a prompt to
            // the user.
            UnconstrainedTransferRequestResult result = await BackgroundDownloader.RequestUnconstrainedDownloadsAsync(requestOperations);

            //Log(String.Format(CultureInfo.CurrentCulture,"Request for unconstrained downloads has been {0}",
            //(result.IsUnconstrained ? "granted" : "denied")));

            await HandleDownloadAsync(download,true);
        }

 /// <summary>
 /// 要下载调用这个方法
 /// </summary>
 /// <param name="url">下载的文件网址的来源</param>
 /// <returns></returns>
 public static async Task Start(string filename,string url,DownloadType type,StorageFolder folder=null)
 {
     try
     {
         Uri uri = new Uri(Uri.EscapeUriString(url), UriKind.RelativeOrAbsolute);
         BackgroundDownloader downloader = new BackgroundDownloader();
         if (folder==null)
         {
             folder = await KnownFolders.MusicLibrary.CreateFolderAsync("kgdownload", CreationCollisionOption.OpenIfExists);
             switch (type)
             {
                 case DownloadType.song:
                     folder = await folder.CreateFolderAsync("song", CreationCollisionOption.OpenIfExists);
                     downloader.TransferGroup = BackgroundTransferGroup.CreateGroup("song");
                     break;
                 case DownloadType.mv:
                     folder = await folder.CreateFolderAsync("mv", CreationCollisionOption.OpenIfExists);
                     downloader.TransferGroup = BackgroundTransferGroup.CreateGroup("mv");
                     break;
                 case DownloadType.other:
                     folder = await folder.CreateFolderAsync("other", CreationCollisionOption.OpenIfExists);
                     downloader.TransferGroup = BackgroundTransferGroup.CreateGroup("other");
                     break;
                 default:
                     break;
             }
         }else
         {
             downloader.TransferGroup = BackgroundTransferGroup.CreateGroup("other");
         }
         //string name = uri.ToString().Substring(uri.ToString().LastIndexOf("/"), uri.ToString().Length);
         string name = filename;
         StorageFile file = await folder.CreateFileAsync(name, CreationCollisionOption.GenerateUniqueName);
         downloader.FailureToastNotification = DownloadedToast.Done(filename, DownloadedToast.DownResult.Fa);
         downloader.SuccessToastNotification = DownloadedToast.Done(filename, DownloadedToast.DownResult.Su);
         var download = downloader.CreateDownload(new Uri(url), file);
         TransferModel transfer = new TransferModel();
         transfer.DownloadOperation = download;
         transfer.Source = download.RequestedUri.ToString();
         transfer.Destination = download.ResultFile.Path;
         transfer.BytesReceived = download.Progress.BytesReceived;
         transfer.TotalBytesToReceive = download.Progress.TotalBytesToReceive;
         transfer.Progress = 0;
         transfers.Add(transfer);
         Progress<DownloadOperation> progressCallback = new Progress<DownloadOperation>(DownloadProgress);
         download.StartAsync().AsTask(cancelToken.Token, progressCallback);
     }
     catch
     {
         await new MessageDialog("链接已失效！").ShowAsync();
     }
 }

        // 非同期ダウンロードする
        private async void Button_Click_1(object sender, RoutedEventArgs e)
        {
            // ダウンロードしたファイルの保存先を指定する
            var uri = new Uri("http://download.thinkbroadband.com/100MB.zip");
//            var uri = new Uri("{バックグランドでダウンロードするファイルのURL}");

            var file = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFileAsync("example.zip", 
                Windows.Storage.CreationCollisionOption.ReplaceExisting);

            // バックグランドで非同期ダウンロードする
            var downloader = new Windows.Networking.BackgroundTransfer.BackgroundDownloader();
            DownloadOperation downloadOperation = downloader.CreateDownload(uri, file);
            var progress = new Progress<DownloadOperation>(NotificationProgress);
            await downloadOperation.StartAsync().AsTask(progress);
        }