不用异步的示例：

static void Main(string[] args)        {            Watch.Start();            string Url1 = "Http://www.tmall.com";            string Url2 = "http://www.taobao.com";            var result1 = CountCharacters(1, Url1);            var result2 = CountCharacters(2, Url2);            for (int i = 0; i < 3; i++)            {                ExtraOperation(i);            }            Console.WriteLine("{0}的字符个数{1}", Url1, result1);            Console.WriteLine("{0}的字符个数{1}", Url2, result1);            Console.ReadLine();        }        public static int CountCharacters(int id, string Url)        {            var wc = new WebClient();            Console.WriteLine("开始调用：id:{0},{1}", id, Watch.ElapsedMilliseconds);            var result = wc.DownloadString(Url);            Console.WriteLine("调用完成：id:{0},{1}", id, Watch.ElapsedMilliseconds);            return result.Length;        }        public static void ExtraOperation(int id)        {            var s = "";            for (int i = 0; i < 6000; i++)            {                s += i;            }            Console.WriteLine("id={0} 的 ExtraOperation调用完成用时{1}", id, Watch.ElapsedMilliseconds);        }

 

使用异步的示例 

static void Main(string[] args)        {            Watch.Start();            string Url1 = "Http://www.tmall.com";            string Url2 = "http://www.taobao.com";            Task
     
       t1 = CountCharacters(1, Url1);            Task
      
        t2 = CountCharacters(2, Url2);            for (int i = 0; i < 3; i++)            {                ExtraOperation(i);            }            Console.WriteLine("{0}的字符个数{1}", Url1, t1.Result);            Console.WriteLine("{0}的字符个数{1}", Url2, t2.Result);            Console.ReadLine();        }        public static async Task
       
         CountCharacters(int id, string Url)        {            var wc = new WebClient();            Console.WriteLine("开始调用：id:{0},{1}", id, Watch.ElapsedMilliseconds);            var result = await wc.DownloadStringTaskAsync(Url);            Console.WriteLine("调用完成：id:{0},{1}", id, Watch.ElapsedMilliseconds);            return result.Length;        }        public static void ExtraOperation(int id)        {            var s = "";            for (int i = 0; i < 6000; i++)            {                s += i;            }            Console.WriteLine("id={0} 的 ExtraOperation调用完成用时{1}", id, Watch.ElapsedMilliseconds);        }