C#异步下载文件--基于http请求

1.废话不多说，直接上代码：

 using System;
 using System.IO;
 using System.Net;

 namespace AsyncProgram
 {
     class Program
     {
         static void Main(string[] args)
         {
             do
             {
                 Console.WriteLine("请输入要下载的文件地址,输入quit退出！");
                 string url = Console.ReadLine();

                 if (url == "quit") break;

                 if (!url.StartsWith("http://"))
                 {
                     Console.WriteLine("只能支持http://开头的下载地址！");
                     continue;
                 }

                 string []strs = url.Split(new char[] { '/'},StringSplitOptions.RemoveEmptyEntries);
                 string fileName = strs[strs.Length-];

                 WebRequest webRequest = WebRequest.Create(url);

                 webRequest.BeginGetResponse(DownloadFinished, new Mystate { FileName = fileName, WebRequestObject = webRequest });

                 Console.WriteLine($"已在后台自动下载文件：{fileName}\r\n");

             } while (true);

             Console.WriteLine("正在下载文件...");

             Console.WriteLine("关闭次窗口前，请确保文件已全部下载完成！按任意键关闭窗口...");

             Console.ReadKey();

         }

         static void DownloadFinished(IAsyncResult ar)
         {
             try
             {
                 Mystate state = ar.AsyncState as Mystate;
                 WebResponse response = state.WebRequestObject.EndGetResponse(ar);

                 Stream inStream = response.GetResponseStream();
                 byte[] buffer = new byte[*];
                 Stream outStream = System.IO.File.Create(System.AppDomain.CurrentDomain.BaseDirectory + state.FileName);
                 try
                 {
                     int l;
                     do
                     {
                         l = inStream.Read(buffer, , buffer.Length);
                         if (l > ) outStream.Write(buffer, , l);
                     } while (l > );
                 }
                 finally
                 {
                     if (outStream != null) outStream.Close();
                     if (inStream != null) inStream.Close();
                 }

             }
             catch (Exception ex)
             {
                 Console.WriteLine(ex.Message);
             }
         }
     }

     public class Mystate
     {
         public string FileName { get; set; }
         public WebRequest WebRequestObject { get; set; }
     }
 }