c#_delegate_异步调用_BeginInvoke

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading;



//异步调用

//IAsyncResult BeginInvoke(argument,AsyncCallback callback,object asynState)

//argument - 如果没有参数，callback就是第一个参数

//BeginInvoke返回值是IAsyncResult

//AsyncState - 传递给异步调用的那个状态对象

//AsyncWaitHandle - 在异步操作完成前，一直使用WaitHandle阻断调用线程

//CompleteSynchronously - 指示一步操作是否同步完成

//IsCompleted - 指示异步操作已经完成



namespace Starter

{

    public delegate void DeleageteClass();



    class Program

    {

        static void Main(string[] args)

        {

            DeleageteClass del = MethodA;



            DelegateStateBag state = new DelegateStateBag();



            IAsyncResult ar = del.BeginInvoke(Callback,state);



            if (ar.IsCompleted == true)

            {

                Console.WriteLine("MethodA completed");

            }

            else

            {

                Console.WriteLine("MethodA not completed");

            }

            

            ar.AsyncWaitHandle.WaitOne();



            //do something else

            

            //Sleep - 不然会产生竞争，同时启动Callback和main，Sleep是消除竞争的根本办法

            Thread.Sleep(100);



            lock (state)

            {

                Console.WriteLine("Back in main");

                Console.WriteLine(state.message);

            }



            Console.ReadLine();

        }



        public static void Callback(IAsyncResult ar)

        {

            DelegateStateBag state = (DelegateStateBag)ar.AsyncState ;

            lock(state)

            {

                Console.WriteLine("Call back running");

                ((DelegateStateBag)ar.AsyncState).message = 

                    "State object modify in callack";

            }



        }





        public static void MethodA()

        {

            Console.WriteLine("MethodA running....");

            Thread.Sleep(200);

        }

    }



    class DelegateStateBag

    {

       public string message;

    }

}