Question

我有一个WPF MVVM应用程序。在其中一个ViewModel中，我有以下内容：

this.GoCommand = new RelayCommand(() =>
{
    var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

    Task.Factory.StartNew(() =>
        {
            for (int i = 0; i < 100; ++i)
            {
                this.Progress = i + 1;
                Thread.Sleep(30);
            }
        }).ContinueWith(task =>
            {
                // should act like RunWorkerCompleted
                this.DoSecondTask();
            },
            scheduler
        );
});

private void DoSecondTask()
{ 
    Task.Factory.StartNew(() =>
        {
            for (int i = 0; i < 100; ++i)
            {
                // repeated task for simplicity
                this.Progress = i + 1;
                Thread.Sleep(30);
            }
        }).ContinueWith(task =>
            {
                this.Status = "Done.";
            }
        );
}

当我点击绑定到GoCommand的按钮时，我看到进度条从1-100移动。但是，当ContinueWith执行DoSecondTask时，该任务在UI线程中运行。如何更改DoSecondTask函数以在新线程（或UI线程之外）中运行第二个for循环？

Answer 1

我在this回答中找到了解决方案。有趣的是，没有工作：

private void DoSecondTask()
{ 
    Task.Factory.StartNew(_ =>
        {
            for (int i = 0; i < 100; ++i)
            {
                // repeated task for simplicity
                this.Progress = i + 1;
                Thread.Sleep(30);
            }
        }, TaskScheduler.Default).ContinueWith(task =>
            {
                this.Status = "Done.";
            }
        );
}

但确实：

private void DoSecondTask()
{ 
    Task.Factory.StartNew(() =>
        {
            for (int i = 0; i < 100; ++i)
            {
                // repeated task for simplicity
                this.Progress = i + 1;
                Thread.Sleep(30);
            }
        }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default).ContinueWith(task =>
            {
                this.Status = "Done.";
            }
        );
}

使用Tasks实现BackgroundWorker的RunWorkerCompleted

1 个答案: