c# – StorageFile.OpenAsync中的UnauthorizedAccessException
作者:互联网
我使用以下代码下载/保存图像并稍后打开它,但在以后的OpenAsync中,它会抛出UnauthorizedAccessException,似乎文件没有关闭,但实际上IRandomAccessStream / DataWriter已被处理掉了.
HttpClient httpClient = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "http://www.silverlightshow.net/Storage/Users/nikolayraychev/Perspective_Transforms_4.gif");
HttpResponseMessage response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
//Write Image File
StorageFile imageFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("test.gif", CreationCollisionOption.ReplaceExisting);
using (IRandomAccessStream fs = await imageFile.OpenAsync(FileAccessMode.ReadWrite))
{
using (DataWriter writer = new DataWriter(fs.GetOutputStreamAt(0)))
{
writer.WriteBytes(await response.Content.ReadAsByteArrayAsync());
await writer.StoreAsync();
writer.DetachStream();
await fs.FlushAsync();
}
}
StorageFile imageFile1 = await ApplicationData.Current.LocalFolder.GetFileAsync("test.gif");
//Exception is throwed here
using (IRandomAccessStream stream = await imageFile1.OpenAsync(FileAccessMode.Read))
{
BitmapImage img = new BitmapImage();
img.SetSource(stream);
}
解决方法:
我遇到了同样的问题,在完成之前必须明确地处理流和文件对象.
var file = await ApplicationData.Current.LocalFolder.CreateFileAsync(filename, Windows.Storage.CreationCollisionOption.ReplaceExisting);
using (var fs = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
var outStream = fs.GetOutputStreamAt(0);
var dataWriter = new Windows.Storage.Streams.DataWriter(outStream);
dataWriter.WriteString("Hello from Test!");
await dataWriter.StoreAsync();
dataWriter.DetachStream();
await outStream.FlushAsync();
outStream.Dispose(); //
fs.Dispose();
}
标签:c,io,windows-runtime,file-access 来源: https://codeday.me/bug/20190530/1182730.html