windows-phone-7 - Windows Phone 7：应用程序不会在独立存储中保存从 URL 下载的 PDF 文件

Question

我正在开发一个应用程序来管理 PDF 文件（不是 PDF 查看器），并且我有一个专用页面来下载具有特定 URL 的 PDF 文件。

我的问题是该应用程序不保存下载的文档。

这是我的应用程序代码（在名为 PDFurl.xaml.cs 的页面类中）：

private void Start_Download(object sender, EventArgs e)
    {
        WebClient PDFdownloader = new WebClient();
        DownloadProgress.Visibility = Visibility.Visible;
        PDFdownloader.DownloadProgressChanged += new DownloadProgressChangedEventHandler(PDFdownloader_DownloadProgressChanged);
        PDFdownloader.OpenReadCompleted += new OpenReadCompletedEventHandler(PDFdownloader_OpenReadCompleted);
        PDFdownloader.OpenReadAsync(new Uri(UrlText.Text));
    }

    void PDFdownloader_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        try
        {
            DownloadProgress.Value = e.BytesReceived;
            DownloadProgress.Maximum = e.TotalBytesToReceive;
        }
        catch (Exception ex)
        {
            MessageBox.Show("Download failed!");
        }
    }

    void PDFdownloader_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
    {
        DownloadProgress.Visibility = Visibility.Collapsed;
        string[] fileNames = storage.GetFileNames();
        foreach (string fileName in fileNames)
        {
            if (fileName == (SavedFile.Text + ".pdf"))    //Save existing file
            {    
                MessageBoxResult rewrite = MessageBox.Show("Already exists a file with this name. Do you want to overwrite it?", "PDF name already used", MessageBoxButton.OKCancel);
                if (rewrite == MessageBoxResult.OK)
                {
                    storage.DeleteFile(SavedFile.Text + "pdf");
                    Save_File(e);
                }
                else
                {
                    MessageBox.Show("Document not saved!");
                    e.Result.Close();
                    DownloadProgress.Value = 0;
                    DownloadProgress.Visibility = Visibility.Collapsed;
                    return;
                }
            }
            else       //Save new file
            {
                Save_File(e);
            }
        }
    }

    private void Save_File(OpenReadCompletedEventArgs e)
    {
        using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(SavedFile.Text + ".pdf", FileMode.Create, storage))
        {
            byte[] buffer = new byte[1024];
            while (e.Result.Read(buffer, 0, buffer.Length) > 0)
            {
                stream.Write(buffer, 0, buffer.Length);
            }
            MessageBox.Show("File downloaded and saved successfully!");
            foreach (string file in storage.GetFileNames())
            {
                MessageBox.Show("Found " + file);
            }
        }   
    }

我包含了一些消息框来监视每个任务，但是当它显示成功下载的消息时，它并没有真正保存任何东西。