我尝试使用FileSavePicker在UWP中覆盖当前文件。我参考了这个链接:https://msdn.microsoft.com/zh-cn/windows/uwp/files/quickstart-reading-and-writing-files。但是当我使用一个较短的文件来覆盖一个较长的文件时,会出现一个问题:旧文件(较长)的额外部分没有被删除,就像这样:
但是在保存操作之后,我得到了以下结果:
旧文件:
abcdefg
我想保存的文件:
hij
但是在保存操作之后,我得到了以下结果:
hijdefg
这是我的代码:
private async void Save_Click(object sender, RoutedEventArgs e)
{
XmlDocument Line = SaveToXml();
//Save it
FileSavePicker fileSaving = new FileSavePicker();
fileSaving.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
fileSaving.SuggestedFileName = "NewLine";
fileSaving.FileTypeChoices.Add("Simple Line Files", new List<string>() { ".Line" });
StorageFile file = await fileSaving.PickSaveFileAsync();
if (file != null)
{
CachedFileManager.DeferUpdates(file);
var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
//var stream = await file.OpenStreamForWriteAsync();
using (var outputStream = stream.GetOutputStreamAt(0))
{
using (var dataWriter = new Windows.Storage.Streams.DataWriter(outputStream))
{
string xmlDoc = Line.OuterXml;
Debug.WriteLine(Line.OuterXml);
dataWriter.WriteString(xmlDoc);
await dataWriter.StoreAsync();
await outputStream.FlushAsync();
}
}
stream.Dispose();
}
}
谢谢你帮助我!