WebRequt与WebResponse实现异步请求!

 1 using System;
 2 using System.Net;
 3 using System.Threading;
 4 using System.Text;
 5 using System.IO;
 6 namespace ConsoleApplication1 {
 7 
 8     public class RequestState {
 9         const int BufferSize=1024;
10         public StringBuilder RequestData;
11         public byte[] BufferRead;
12         public WebRequest Request;
13         public Stream ResponseStream;
14         public Decoder StreamDecode=Encoding.UTF8.GetDecoder();
15 
16         public RequestState() {
17             this.BufferRead=new byte[BufferSize];
18             RequestData=new StringBuilder(String.Empty);
19             Request=null;
20             ResponseStream=null;
21         }
22 
23     }
24 
25     class ClientGetAsync {
26         public static ManualResetEvent allDone=new ManualResetEvent(false);
27         const int BUFFER_SIZE=1024;
28         
29         [STAThread]
30         static void Main(string[] args) {
31             //只能是网址,不能是文件啊????
32 //            string strURI="http://nmgsk.onlinedown.net/down/mcombocn.exe";
33             string strURI="http://www.163.com";
34             Uri httpSite=new Uri(strURI);
35             WebRequest wreq=WebRequest.Create(httpSite);
36             RequestState rs=new RequestState();
37             rs.Request=wreq;
38             IAsyncResult r=(IAsyncResult)wreq.BeginGetResponse(
39                 new AsyncCallback(RespCallback),rs);
40             allDone.WaitOne();
41             Console.WriteLine(rs.RequestData.ToString());
42         }
43 
44         private static void RespCallback(IAsyncResult ar) {
45             RequestState rs=(RequestState)ar.AsyncState;
46             WebRequest req=rs.Request;
47             WebResponse resp=req.EndGetResponse(ar);
48             Stream ResponseStream=resp.GetResponseStream();
49             rs.ResponseStream=ResponseStream;
50             //读指定大小的字节
51             IAsyncResult iarRead=ResponseStream.BeginRead(rs.BufferRead,0,
52                 BUFFER_SIZE,new AsyncCallback(ReadCallBack),rs);
53         }
54 
55         //异步读取的方式,值得看看,居然是递归调用的形式,头次看到.
56         private static void ReadCallBack(IAsyncResult asyncResult) {
57             RequestState rs=(RequestState)asyncResult.AsyncState;
58             Stream responseStream=rs.ResponseStream;
59             int read=responseStream.EndRead(asyncResult);
60             if (read>0) {
61                 Char[] charBuffer=new char[BUFFER_SIZE];
62                 int len=rs.StreamDecode.GetChars(rs.BufferRead,0,read,charBuffer,0);
63                 string str=new string(charBuffer,0,len);
64                 rs.RequestData.Append(Encoding.ASCII.GetString(rs.BufferRead,0,read));
65                 IAsyncResult ar=responseStream.BeginRead(
66                     rs.BufferRead,0,BUFFER_SIZE,new AsyncCallback(ReadCallBack),rs);
67             }
68             else {
69                 if (rs.RequestData.Length>0) {
70                     string strContent;
71                     strContent=rs.RequestData.ToString();
72                 }
73                 responseStream.Close();
74                 allDone.Set();                        //发出信号,使等待的线程继续
75             }
76             return;
77         }
78     }
79 }
80