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I'm writing a cross-platform app, so thought I'd do the UI in XAML with C++/CX resp. Cocoa, and the core in standard C++. However, I'm having problems accessing documents.

I present a FolderPicker and take the path and stick it in a directory_iterator, but the directory iterator doesn't find any files, and if I call exists() on the path, it says false.

I've googled high and low, but everything on the net tells me that I should just have access to the files once I have the StorageFolder, and nothing refers to Standard C++17 APIs.

What do I have to do to give the standard library access to the files?

I bring up the file picker using:

FolderPicker    ^picker = ref new FolderPicker;
picker->FileTypeFilter->Append( "*" );
IAsyncOperation<StorageFolder ^> ^storageFolderOp = picker->PickSingleFolderAsync();
auto asyncTask = concurrency::create_task(storageFolderOp);
asyncTask.then([this](StorageFolder ^storageFolder)
               {
                   cout << "Picked directory: " << StdStringFromString(storageFolder->Path) << endl;
                   commandsPathField->Text = storageFolder->Path;
               });

Code that takes this string (as a std::string) and tries to list files in that directory:

path    commandsFolderPath(inFolderPath);
if (exists(commandsFolderPath))
{
    directory_iterator    directoryIterator(commandsFolderPath);
    for ( ; directoryIterator != directory_iterator(); ++directoryIterator )
    {
        const directory_entry& currFile = *directoryIterator;
        if (currFile.path().filename().string().compare("data") == 0 || currFile.path().filename().string().find(".") == 0)
        {
            continue;
        }
        load_one_command_folder(currFile.path().string());
    }
}
else
{
    cout << "No directory " << commandsFolderPath.string() << endl;
}

And my manifest:

<Package
  xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
  xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
  IgnorableNamespaces="uap mp rescap">

  <Identity
    Name="69b58249-31af-4bb3-95f4-fd339268a557"
    Publisher="CN=Uli"
    Version="1.0.0.0" />

  <mp:PhoneIdentity PhoneProductId="69b58249-31af-4bb3-95f4-fd339268a557" PhonePublisherId="00000000-0000-0000-0000-000000000000"/>

  <Properties>
<DisplayName>VanguardBotGUI</DisplayName>
<PublisherDisplayName>Uli Kusterer</PublisherDisplayName>
<Logo>Assets\StoreLogo.png</Logo>
  </Properties>
  <Dependencies>
    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.0.0" MaxVersionTested="10.0.0.0" />
  </Dependencies>
  <Resources>
    <Resource Language="x-generate" />
  </Resources>
  <Applications>
    <Application Id="App"
      Executable="$targetnametoken$.exe"
      EntryPoint="vanguardbot_win.App">
      <uap:VisualElements
        DisplayName="vanguardbot_win"
        Square150x150Logo="Assets\Square150x150Logo.png"
        Square44x44Logo="Assets\Square44x44Logo.png"
        Description="vanguardbot_win"
        BackgroundColor="transparent">
        <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png"/>
        <uap:SplashScreen Image="Assets\SplashScreen.png" />
      </uap:VisualElements>
    </Application>
  </Applications>
  <Capabilities>
    <Capability Name="internetClient" />
    <Capability Name="internetClientServer" />
    <rescap:Capability Name="appDiagnostics" />
  </Capabilities>
</Package>

The full code is at https://github.com/uliwitness/vanguardbot in case you want to run it and step through (just make up username/password for the UI, the failure is before that point). Relevant files are windows/MainPage.xaml.cpp (vanguardbot_win::MainPage::FolderPicker_Click), common/vanguardbot.cpp (vanguardbot::connect) and vanguardbot/windows/Package.appxmanifest. The solution is vanguardbot_win.sln at the top level.

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1 回答 1

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不幸的是，从 a 返回的文件夹FolderPicker是一个“代理”位置，这意味着对它的所有访问都是通过执行适当安全检查的进程外组件发生的。WinRT 存储 API 知道如何处理这些代理位置，但标准 CRT / STL 函数不知道（此时）。需要更新这些库以在后台调用较新的 Win32 API，以便正确处理代理位置。

目前，您要么必须使用Windows.StorageAPI，要么直接使用 Win32 API，例如FindFirstFileExFromApp可以处理代理位置的 API。

于 2018-07-22T22:33:55.930 回答