C＃.NET 2.0中带有静态方法的异步调用 [英] Asynchronous call with a static method in C# .NET 2.0

问题描述

我有一个.NET 2.0应用程序。在此应用程序中，我需要将数据传递回我的服务器。服务器公开了一个基于REST的URL，我可以将数据发布到该URL。当我将数据传递回服务器时，有时需要异步进行，而其他时候则需要阻塞调用。在异步调用的情况下，我需要知道调用何时完成。到目前为止，我都知道该怎么做。

I have a .NET 2.0 application. In this application, I need to pass data back to my server. The server exposes a REST-based URL that I can POST data to. When I pass data back to my server, I need to sometimes do so asynchronously, and other times I need a blocking call. In the scenario of the asynchronous call, I need to know when the call is completed. Everything up to this point I understand how to do.

我遇到麻烦的地方是，我正在研究的方法必须是静态的。它是我继承的代码，我不想重做所有这些代码。当前，我有两种静态方法：

Where I get into trouble is, the method that I am working on MUST be static. It's code I've inherited, and I'd rather not have to redo all of this code. Currently, I have two static methods:

public static string SendData (...) {
}

public static string SendDataAsync(...) {

}

返回的字符串是服务器的响应代码。静态部分让我很健康。我的屏蔽版本没有问题。但是，在异步调用的竞赛中，我不确定该怎么办。

The string returned is a response code from the server. The static part is giving me fits. It doesn't cause a problem in my blocking version. However, in the contest of the asynchronous call, I'm not sure what to do.

有人可以提供任何见解吗？

Does anyone have any insights they can provide?

推荐答案

这是C＃5（IIRC）之前的通用异步模式。

This is the general async pattern before C# 5 (IIRC).

public static string SendData (...) {
}

public static IAsyncResult BeginSendData(..., AsyncCallback cb) {
   var f = new Func<..., string>(SendData);
   return f.BeginInvoke(..., cb, f);
}

public static string EndSendData(IAsyncResult ar) {
   return ((Func<..., string>) ar.AsyncState).EndInvoke(ar); 
}

用法：

BeginSendData(..., ar => 
   {
     var result = EndSendData(ar);
     // do something with result
   });

完整的控制台示例：

public static string SendData(int i)
{
    // sample payload
    Thread.Sleep(i);
    return i.ToString();
}

public static IAsyncResult BeginSendData(int i, AsyncCallback cb)
{
    var f = new Func<int, string>(SendData);
    return f.BeginInvoke(i, cb, f);
}

public static string EndSendData(IAsyncResult ar)
{
    return ((Func<int, string>)ar.AsyncState).EndInvoke(ar);
}

static void Main(string[] args)
{
    BeginSendData(2000, ar => 
        {
            var result = EndSendData(ar);
            Console.WriteLine("Done: {0}", result);
        });

    Console.WriteLine("Waiting");
    Console.ReadLine();
}

上面将显示：

Waiting
Done: 2000

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