Question

我正在尝试读取用OpenFilePicker选择的CSV文件并将其放入FutureAccessList。但是，每当我尝试阅读它时，我都会得到DeniedAccessException。

该功能是一个测试：

private async Task readCSVCustomAsync()
{
    ApplicationDataContainer localSettings = ApplicationData.Current.LocalSettings;
    StorageFile file;
    FileOpenPicker openPicker = new FileOpenPicker();
    openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
    openPicker.FileTypeFilter.Add("*");
    //picking a file with FilePicker
    file = await openPicker.PickSingleFileAsync();
    //Storing file in futureaccesslist
    string faToken = StorageApplicationPermissions.FutureAccessList.Add(file);

    //getting the file from FA list
    var fileOpenTest = await StorageApplicationPermissions.FutureAccessList.GetFileAsync(faToken);

    //trying to read it
    using (var reader = new StreamReader(fileOpenTest.Path)) //Exception here
    using (var csv = new CsvReader(reader))
    {
        //elimination des premieres lignes avant le header
        bool headerOK = false;
        while (csv.Read() && !headerOK)
        {
            string rec = csv.GetField(0) + csv.GetField(1);
            if (!rec.Equals(""))
            {
                csv.ReadHeader();
                headerOK = true;
            }
        }
    }
}

所以在这里，我试图将文件放入FA列表中，并在以后检索它以读取内容（这是我选择的一个csv文件）。

但是，即使我将其放在FutureAccessList中，但在尝试阅读时还是得到了AccessDeniedException，为什么我会收到该异常？

Answer 1

无法读取FutureAccessList中的文件

问题是您无法使用System.IO.StreamReader访问FutureAccessList中带有路径的文件，而path属性仅在Windows Storage API中可用。因此，您需要以流方式打开文件，然后调用此var reader = new StreamReader(stream)。

private async Task readCSVCustomAsync()
{
    ApplicationDataContainer localSettings = ApplicationData.Current.LocalSettings;
    StorageFile file;
    FileOpenPicker openPicker = new FileOpenPicker();
    openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
    openPicker.FileTypeFilter.Add("*");
    //picking a file with FilePicker
    file = await openPicker.PickSingleFileAsync();
    //Storing file in futureaccesslist
    string faToken = StorageApplicationPermissions.FutureAccessList.Add(file);

    //getting the file from FA list
    var fileOpenTest = await StorageApplicationPermissions.FutureAccessList.GetFileAsync(faToken);
     // open file as stream, to avoid using path property
    var stream = await fileOpenTest.OpenStreamForReadAsync();
    //trying to read it
    using (var reader = new StreamReader(stream)) 
    using (var csv = new CsvReader(reader))
    {
        //elimination des premieres lignes avant le header
        bool headerOK = false;
        while (csv.Read() && !headerOK)
        {
            string rec = csv.GetField(0) + csv.GetField(1);
            if (!rec.Equals(""))
            {
                csv.ReadHeader();
                headerOK = true;
            }
        }
    }
}

无法读取FutureAccessList中的文件

1 个答案: