Writing Data into a File on Hololens

问题:

in my Hololens app i want to write data into a file which i can then view over the Device Portal. The Data contains just the time from one airtap on a special object to another airtap. The problem ist that there will be no file created in the Device Portal under /LocalAppData/YourApp/LocalState

Thanks in advance

Jonathan

public void StopTime()

{

    TimeSpan ts = time.Elapsed;
    time.Stop();
    path = Path.Combine(Application.persistentDataPath, "Messdaten.txt");
    using (TextWriter writer = File.CreateText(path))
    {
        writer.Write(ts);
    }
}

回答1:

I usually use a FileStream and a StreamWriter and make sure the FileMode.Create is set.

See also How to write text to a file for more approaches

using (var file = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.Write))
{
    using (var writer = new StreamWriter(file, Encoding.UTF8))
    {
        writer.Write(content);
    }
}

With that I never had any trouble on the HoloLens so far.

You also might want to use something like ts.ToString() in order to format the value to your needs.

---

Alternatively you could also try Unity's Windows.File (only available for UWP) but than you need to have byte[] as input. E.g. from here

long c = ts.Ticks;
byte[] d = BitConverter.GetBytes(c);

File.WriteAllBytes(path, d);

回答2:

The simplest thing to do is to use File.WriteAllText method https://docs.microsoft.com/en-us/dotnet/api/system.io.file.writealltext?view=netframework-4.7.2

Obviously there are many ways that could work but it is good to stick to the simplest solution.