其实这也是面试中被问倒的问题:(贴在这里纪念一下，注：只是简单的罗列，详细原理及分析，请参阅《CLR Via c#》第三版相关章节)1、利用线程池发起异步操作

using System;
using System.Threading;
 
namespace Asynchronous
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("主线程:准备发起一系列异步操作...");
            ThreadPool.QueueUserWorkItem(ComputeBoundOp, 5);
            ThreadPool.QueueUserWorkItem(ComputeBoundOp, 7);
            Console.WriteLine("主线程：干其它事情...");
            Thread.Sleep(1000);
            Console.WriteLine("按回车退出...");
            Console.ReadLine();
        }
 
        private static void ComputeBoundOp(object o)
        {
            Console.WriteLine("异步操作回调:state={0}", o);
            Thread.Sleep(1000);
        }
    }
}

结果：

或2、利用Threading.Tasks中的Task

using System;
using System.Threading;
using System.Threading.Tasks;
 
namespace Asynchronous
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("主线程:准备发起一系列异步操作...");
            Task t = new Task(ComputeBoundOp,5);
            t.Start();
            Console.WriteLine("主线程：干其它事情...");
            Thread.Sleep(1000);
            Console.WriteLine("按回车退出...");
            Console.ReadLine();
        }
 
        private static void ComputeBoundOp(object o)
        {
            Console.WriteLine("异步操作回调:state={0}", o);
            Thread.Sleep(1000);
        }
    }
}

3、利用System.Threading.Timer

using System;
using System.Threading;
 
 
namespace Asynchronous
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("主线程:准备发起一系列异步操作...");
            Timer t = new Timer(ComputeBoundOp, 5, 50, 0);
            Console.WriteLine("主线程：干其它事情...");
            Thread.Sleep(1000);
            Console.WriteLine("按回车退出...");
            Console.ReadLine();
        }
 
        private static void ComputeBoundOp(object o)
        {
            Console.WriteLine("异步操作回调:state={0}", o);
            Thread.Sleep(1000);
        }
    }
}

4、利用APM(Asynchronous Programming Model)中的beginXXX方法

using System;
using System.Threading;
 
namespace Asynchronous
{
    class Program
    {
        delegate void MyDelegate(object o);
 
        static void Main(string[] args)
        {
            Console.WriteLine("主线程:准备发起一系列异步操作...");
            MyDelegate mydelegate = ComputeBoundOp;
            mydelegate.BeginInvoke(null,ComputeBoundOpCallBack,5);            
            Console.WriteLine("主线程：干其它事情...");
            Thread.Sleep(5000);
            Console.WriteLine("按回车退出...");
            Console.ReadLine();
        }
 
        private static void ComputeBoundOp(object o)
        {           
            Thread.Sleep(1000);//模拟异步操作在做一些耗时的操作
        }
 
        private static void ComputeBoundOpCallBack(IAsyncResult ar)
        {
            Console.WriteLine("异步操作的回调：{0}" , ar.AsyncState);
             
        }
    }
}