我使用下面的代码在
WPF页面异步方式中执行耗时的操作以及向UI报告进度
private void btnStart_Click(object sender, RoutedEventArgs e)
{
txt_importStatus.Text = "";
var progress = new Progress<string>(progress_info =>
{
//show import progress on a textfield
txt_importStatus.Text = progress_info + Environment.NewLine + "Please dont close this window while the system processing the excel file contents";
});
// DoProcessing is run on the thread pool.
await Task.Run(() => DoProcessing(progress));
}
public void DoProcessing(IProgress<string> progress)
{
//read an excel file and foreach excel file row
foreach(excelrow row in excelrowlist)
{
//do db entry and update UI the progress like
progress.Report("Processed x number of records. please wait..");
}
}
现在我想添加一个额外的选项,在中间取消这个异步操作.为此我发现我必须添加以下选项
CancellationTokenSource tokenSource = new CancellationTokenSource();
CancellationToken token = tokenSource.Token;
private void btnCacnel_Click(object sender, RoutedEventArgs e)
{
tokenSource.Cancel();
}
但是如何将此tokenSource传递给我的DoProcessing调用以及如何在DoProcessing中处理取消
最佳答案 实际上,您不需要将CancellationTokenSource传递给DoProcessing,而只需要将CancellationToken传递给DoProcessing.
为了处理取消,您可以执行以下操作:
public void DoProcessing(CancellationToken token, IProgress<string> progress)
{
//read an excel file and foreach excel file row
foreach(excelrow row in excelrowlist)
{
if(token.IsCancellationRequested)
break;
//do db entry and update UI the progress like
progress.Report("Processed x number of records. please wait..");
}
}
在这种情况下,您需要在btnStart_Click中创建取消令牌源.如果不清楚,你需要这样做:
CancellationTokenSource tokenSource;
private void btnStart_Click(object sender, RoutedEventArgs e)
{
txt_importStatus.Text = "";
var progress = new Progress<string>(progress_info =>
{
//show import progress on a textfield
txt_importStatus.Text = progress_info + Environment.NewLine + "Please dont close this window while the system processing the excel file contents";
});
// DoProcessing is run on the thread pool.
tokenSource = new CancellationTokenSource();
var token = tokenSource.Token;
await Task.Run(() => DoProcessing(token, progress));
}