C#异步下载文件--基于http请求

1.废话不多说，直接上代码：
 1 using System;
 2 using System.IO;
 3 using System.Net;
 4 
 5 namespace AsyncProgram
 6 {
 7     class Program
 8     {
 9         static void Main(string[] args)
10         {
11             do
12             {
13                 Console.WriteLine("请输入要下载的文件地址,输入quit退出！");
14                 string url = Console.ReadLine();
15 
16                 if (url == "quit") break;
17 
18                 if (!url.StartsWith("http://"))
19                 {
20                     Console.WriteLine("只能支持http://开头的下载地址！");
21                     continue;
22                 }
23 
24                 string []strs = url.Split(new char[] { '/'},StringSplitOptions.RemoveEmptyEntries);
25                 string fileName = strs[strs.Length-1];
26 
27                 WebRequest webRequest = WebRequest.Create(url);
28 
29                 webRequest.BeginGetResponse(DownloadFinished, new Mystate { FileName = fileName, WebRequestObject = webRequest });
30 
31                 Console.WriteLine($"已在后台自动下载文件：{fileName}
");
32 
33             } while (true);
34 
35             Console.WriteLine("正在下载文件...");
36 
37             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...");
38 
39             Console.ReadKey();
40 
41         }
42 
43         static void DownloadFinished(IAsyncResult ar)
44         {
45             try
46             {
47                 Mystate state = ar.AsyncState as Mystate;
48                 WebResponse response = state.WebRequestObject.EndGetResponse(ar);
49 
50                 Stream inStream = response.GetResponseStream();
51                 byte[] buffer = new byte[1024*1024];
52                 Stream outStream = System.IO.File.Create(System.AppDomain.CurrentDomain.BaseDirectory + state.FileName);
53                 try
54                 {
55                     int l;
56                     do
57                     {
58                         l = inStream.Read(buffer, 0, buffer.Length);
59                         if (l > 0) outStream.Write(buffer, 0, l);
60                     } while (l > 0);
61                 }
62                 finally
63                 {
64                     if (outStream != null) outStream.Close();
65                     if (inStream != null) inStream.Close();
66                 }
67 
68             }
69             catch (Exception ex)
70             {
71                 Console.WriteLine(ex.Message);
72             }
73         }
74     }
75 
76     public class Mystate
77     {
78         public string FileName { get; set; }
79         public WebRequest WebRequestObject { get; set; }
80     }
81 }