c# uwp 从网络读取 csv

Question

I am trying to make an app that make use of open data. The data I try to read out is in a CSV format (and is about 40mb big).

I have 2 problems I can't solve.

• First I having difficulties to read the file from the web. I already read on MSDN how to read files asynchrome but it's all about local files. I want to make a list of objects. Each line (except the first line) contains all props for 1 object

• Secondly when I finally managed to read the file, is there a way to save it's data and read it somehow the next time? Because 40mb is pretty big to re-download each time you open the app and it takes a lot of time. I was wondering if it is possible that when I read the the file on the web again, it will only read and at the new lines.

I am a newbie in UWP (c#) applications, so my apologies for the questions.

Thanks in advance.

Answer 1

There are two APIs you can use to download a file. One is HttpClient , described here on MSDN Documentation and in a UWP sample here . This class is usually recommended for smaller files and smaller data, but can easily handler larger files as well. Its disadvantage is, that when the user closes the app, the file will stop downloading.

The alternative is BackgroundDownloader , again here on MSDN and here in UWP samples . This class is usually recommended for downloading larger files and data, as it automatically perfroms the download in the background so the download will continue even when the app is closed.

To store your files, you can use the ApplicationData.Current.LocalFolder . This is a special folder provided to you by the system for storage of application files. You have read/write access to this folder and you can not only store your files here, but even create subfolder structure using UWP StorageFile and StorageFolder APIs. More about this is on MSDN .