C# 异步回调通过引用变量获取值

C# 异步回调通过引用变量获取值,c#,.net,asynchronous,asynccallback,C#,.net,Asynchronous,Asynccallback,我需要使用异步委托调用函数,当我阅读异步回调教程时,我看到异步回调定义如下: static void CallbackMethod(IAsyncResult result) { // get the delegate that was used to call that // method CacheFlusher flusher = (CacheFlusher) result.AsyncState; // get the return value from that

我需要使用异步委托调用函数,当我阅读异步回调教程时,我看到异步回调定义如下:

static void CallbackMethod(IAsyncResult result)
{
   // get the delegate that was used to call that
   // method
   CacheFlusher flusher = (CacheFlusher) result.AsyncState;

   // get the return value from that method call
   int returnValue = flusher.EndInvoke(result);

   Console.WriteLine("The result was " + returnValue);
}       
请告诉我是否可以从函数中获取返回值作为引用。例如:=我的函数的格式是

void GetName(int id,ref string Name);

在这里,我通过一个引用变量获得函数的输出。如果使用异步委托调用此函数,如何读取回调函数的输出?

不要通过
ref
参数传回返回值。相反,将签名更改为:

string GetName(int id)
或者可能:

string GetName(int id, string defaultName) // Or whatever

请注意,“引用”和“通过引用传递”之间有很大的区别。理解区别很重要。

您需要将参数包装到对象中:

class User
{
    public int Id { get; set; }

    public string Name { get; set; }
}

void GetName(IAsyncResult result)
{
    var user = (User)result.AsyncState
    // ...
}

AsyncCallback callBack = new AsyncCallback(GetName);