C#中异步回调函数用法实例

static void Main(string[] args){ Func<string,string> showMessage = ShowMessage; //设置了回调函数Completed,不能有返回值 IAsyncResult result = showMessage.BeginInvoke("测试异步委托",new AsyncCallback(Completed),null); //半段异步是否结束 while(!result.IsCompleted) {  Console.WriteLine("主线程可以进行其它的操作！"); } Console.ReadLine();}static string ShowMessage(string x){ string current = string.Format("当前线程id为{0}",Thread.CurrentThread.ManagedThreadId); Thread.Sleep(3000); return string.Format("{0},输入为{1}", current, x);}static void Completed(IAsyncResult result){ Console.WriteLine("异步完成！"); //获取委托对象，并用EndInvoke方法获取返回结果 AsyncResult _result = (AsyncResult) result; Func<string, string> showMessage = (Func<string, string>) _result.AsyncDelegate; //结束异步操作并输出 Console.WriteLine(showMessage.EndInvoke(_result));}