我在 Silverlight 3 中的 SaveFileDialog 遇到了奇怪的异常。我真的不知道问题出在哪里。
我在用户控件的 Loaded 事件中创建SaveFileDialog的实例。单击下载按钮并且dialogResult为true后开始异步文件下载。文件下载完成后,调用方法 OpenFile()。这一次可以正常工作,但第二次我得到异常:
异常消息:
"No file was selected"
细节:
{System.InvalidOperationException: No file was selected.
at System.Windows.Controls.SaveFileDialog.OpenFile()
at Spaces.Client.Views.Dialogs.FileDialog.BL_DownloadFileCompleted(Object sender, EventArguments`1 e)
at Spaces.Client.BL.Interface.DownloadFileCompletedEventHandler.Invoke(Object sender, EventArguments`1 e)
at Spaces.Client.BL.WebService.SpacesService._spacesService_DownloadFileCompleted(Object sender, DownloadFileCompletedEventArgs e)
at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
at Spaces.Client.BL.SpacesServiceReference.ServiceClient.OnDownloadFileCompleted(Object state)}
堆:
at System.Windows.Controls.SaveFileDialog.OpenFile()
at Spaces.Client.Views.Dialogs.FileDialog.BL_DownloadFileCompleted(Object sender, EventArguments`1 e)
at Spaces.Client.BL.Interface.DownloadFileCompletedEventHandler.Invoke(Object sender, EventArguments`1 e)
at Spaces.Client.BL.WebService.SpacesService._spacesService_DownloadFileCompleted(Object sender, DownloadFileCompletedEventArgs e)
at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
at Spaces.Client.BL.SpacesServiceReference.ServiceClient.OnDownloadFileCompleted(Object state)
这里的代码片段:
private void _userControlFileDialog_Loaded(object sender, RoutedEventArgs e)
{
_comboBoxVersions.ItemsSource = _file.Versions;
if (_comboBoxVersions.Items.Count > 0)
_comboBoxVersions.SelectedIndex = 0;
String extension = "*." + _file.Extension;
_sfd = new SaveFileDialog();
_sfd.DefaultExt = _file.Extension;
_sfd.Filter = extension + "|" + extension;
}
private void _hyperlinkButtonDownload_Click(object sender, RoutedEventArgs e)
{
string path = ((FileVersion)_comboBoxVersions.SelectedItem).Url;
bool? dialogResult = _sfd.ShowDialog();
if (dialogResult == true)
{
AppContext.BL.DownloadFileCompleted += new Spaces.Client.BL.Interface.DownloadFileCompletedEventHandler(BL_DownloadFileCompleted);
AppContext.BL.DownloadFileAsync(AppContext.AuthenticatedUser, path);
}
}
void BL_DownloadFileCompleted(object sender, Spaces.Client.BL.Interface.EventArguments<byte[]> e)
{
byte [] data = e._result;
using (Stream fileStream = (Stream)_sfd.OpenFile())
{
fileStream.Write(data, 0, data.Length);
fileStream.Flush();
fileStream.Close();
}
}
有人知道出了什么问题吗?
问候安东卡尔奇克