如何创建在C＃中的异步方法？ [英] How do you create an asynchronous method in C#?

问题描述

每一个博客文章我读过告诉您如何消耗在C＃中的异步方法，但对于一些奇怪的原因从来没有解释如何构建自己的异步方法消耗。所以我有这个code现在消耗我的方法：

Every blog post I've read tells you how to consume an asynchronous method in C#, but for some odd reason never explain how to build your own asynchronous methods to consume. So I have this code right now that consumes my method:

private async void button1_Click(object sender, EventArgs e)
{
    var now = await CountToAsync(1000);
    label1.Text = now.ToString();
}

和我写的这个方法就是 CountToAsync ：

And I wrote this method that is CountToAsync:

private Task<DateTime> CountToAsync(int num = 1000)
{
    return Task.Factory.StartNew(() =>
    {
        for (int i = 0; i < num; i++)
        {
            Console.WriteLine("#{0}", i);
        }
    }).ContinueWith(x => DateTime.Now);
}

是这样的，使用 Task.Factory ，最好的方法写一个异步方法，或者我应该写这个法子？

Is this, the use of Task.Factory, the best way to write an asynchronous method, or should I write this another way?

推荐答案

我不建议 StartNew 除非你需要复杂的那个级别。

I don't recommend StartNew unless you need that level of complexity.

如果您的异步方法是依赖于其他异步方法，最简单的方法是使用异步关键字：

If your async method is dependent on other async methods, the easiest approach is to use the async keyword:

private static async Task<DateTime> CountToAsync(int num = 10)
{
  for (int i = 0; i < num; i++)
  {
    await Task.Delay(TimeSpan.FromSeconds(1));
  }

  return DateTime.Now;
}

如果您的异步方法是做CPU的工作，你应该使用 Task.Run ：

If your async method is doing CPU work, you should use Task.Run:

private static async Task<DateTime> CountToAsync(int num = 10)
{
  await Task.Run(() => ...);
  return DateTime.Now;
}

您可能会发现我的<一个href=\"http://blog.stephencleary.com/2012/02/async-and-await.html\"><$c$c>async/<$c$c>await介绍有帮助的。

You may find my async/await intro helpful.

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