在C＃中取消任务方法

Question

我的View Model

中有这样的异步方法

public async Task Download()
{
//Do some background thread to do heavywork and recursive task
await Download();
}

然后我称之为我的观点

private async Task LoadData()
{
_vm.Download();
//Do other background task
await _vm.DoElse();
}

并像这样称呼它

Task.Factory.StartNew(async()=> {await LoadData();});

现在我的问题是如何取消Download()？

Answer 1

您应该传递给异步方法CancellationToken。

然后你应该在每次迭代时检查它：

public async Task Download(CancellationToken cancellationToken)
{
    if (cancellationToken.IsCancellationRequested)
    {
        //Do work on cancel
        return;
    }
    //Do some background thread to do heavywork and recursive task
    await Download();
}

要在外面取消它，您应该处理CancellationTokenSource对象之外的某个位置，当您想要取消时，只需致电_cancellationTokenSource.Cancel()

Task.Factory.StartNew(async()=> {await LoadData(_cancellationTokenSource.Token);});

private async Task LoadData(CancellationToken cancellationToken)
{
    await _vm.Download(cancellationToken);
    //Do other background task
    await _vm.DoElse(cancellationToken);
}