从网络下载文件并保存在手机中：Windows Phone 8.1 (SilverLight) 开发

Question

我需要从服务器下载 ".Doc , .pdf , .xls , .Jpeg, .PNG etc" 等文件并存储到手机内存中而不是隔离。我进行了很多搜索，但找不到 .doc 、 .pdf 的任何内容。我有一个链接Downloading and saving a file Async in Windows Phone 8 但不能工作。因此，如果有人可以做到这一点，请告诉我。 提前致谢。

Answer 1

我已经完成了 FileSavePicker ，这里是代码

    public void DownloadFiles(Uri url)
    {

        var wc = new WebClient();
        wc.OpenReadCompleted +=async (s, e) =>
        {
            Stream st = e.Result;
            buf = ReadFully(st);
            FileSavePicker savePicker = new FileSavePicker();

            savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;

            // Dropdown of file types the user can save the file as
            savePicker.FileTypeChoices.Add("PDF", new List<string>() { ".pdf" });

            // Default file name if the user does not type one in or select a file to replace
            savePicker.SuggestedFileName = "New Document";

            savePicker.PickSaveFileAndContinue();


            StorageFile SF = await KnownFolders.PicturesLibrary.CreateFileAsync
                      ("Guide.pdf", CreationCollisionOption.ReplaceExisting);
            var fs = await SF.OpenAsync(FileAccessMode.ReadWrite);
            StorageStreamTransaction transaction = await SF.OpenTransactedWriteAsync();
            DataWriter dataWriter = new DataWriter(transaction.Stream);
            dataWriter.WriteBytes(buf);
            transaction.Stream.Size = await dataWriter.StoreAsync(); // reset stream size to override the file
            await transaction.CommitAsync();
        };
        wc.OpenReadAsync(url);

    }

  public static byte[] ReadFully(Stream input)
    {
        byte[] buffer = new byte[16 * 1024];
        using (MemoryStream ms = new MemoryStream())
        {
            int read;
            while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
            {
                ms.Write(buffer, 0, read);
            }
            return ms.ToArray();
        }
    }
   private async void ContinueFileOpenPicker(FileSavePickerContinuationEventArgs args)
    {
        StorageFile file = args.File;
        if (file != null)
        {
            // Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync.
            CachedFileManager.DeferUpdates(file);
            // write to file
            await FileIO.WriteBytesAsync(file, buf);
            // Let Windows know that we're finished changing the file so the other app can update the remote version of the file.
            // Completing updates may require Windows to ask for user input.
            FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file);
            if (status == FileUpdateStatus.Complete)
            {
                Debug.WriteLine("File " + file.Name + " was saved.");
            }
            else
            {
                Debug.WriteLine("File " + file.Name + " couldn't be saved.");
            }
        }
        else
        {
            Debug.WriteLine("Operation cancelled.");
        }
        await Windows.System.Launcher.LaunchFileAsync(file);
    }

欲了解更多信息，请使用此网址How to continue your Windows Phone app after calling a file picker

Answer 2

我认为您不能直接下载文件并将其存储到存储卡中，因为出于安全目的，它们的访问权限受到限制。我猜Isolated Storage 可能是一个选项。

Reference