异步的两种写法: async 与 BeginInvoke

现在要实现异步只要用关键字async/await就可以轻松实现,在此之前需要用到委托/回调等一堆东西。

对一下是对比写法：

  class Program
    {
        delegate string SendMessage(string msg);
        static void Main(string[] args)
        {
            SendMessage sm = new SendMessage(DoAction);
            sm.BeginInvoke("asyn asyn asyn ... ...", new AsyncCallback(CallBack), null);

            DoAsync("async keywod.. ...");

            Console.WriteLine("do do do .... ...");

            Console.ReadLine();
        }
         
        static void CallBack(IAsyncResult result)
        {
            SendMessage sm = (SendMessage)((System.Runtime.Remoting.Messaging.AsyncResult)result).AsyncDelegate;           
            Console.WriteLine(sm.EndInvoke(result));
        }

        static string DoAction(string msg)
        {          
            Thread.Sleep(3000);            
            return msg;
        } 

        static  Task<string> DoTask(string msg)
        {
            return Task.Run(() =>
            {
                Thread.Sleep(1000);
                return msg;
            });           
        }

        static async void DoAsync(string msg)
        {
            Console.WriteLine(await DoTask(msg));
        }