一个httpwebrequest异步下载的例子

namespace 异步调用方法
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 0; i < 1111; i++)
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.cnblogs.com/qianlifeng/");
                request.BeginGetResponse(new AsyncCallback(OnResponse), request);
                Console.WriteLine("请求" + i + "完成");
            }
            Console.Read();
        }

        static void OnResponse(IAsyncResult ar)
        {
            HttpWebRequest request = (HttpWebRequest)ar.AsyncState;
            HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(ar);
            Stream stream = response.GetResponseStream();
            StreamReader sr = new StreamReader(stream, Encoding.UTF8);
            Console.WriteLine(sr.ReadToEnd());
        }
   }

}