学步园

上次说了，如何通过post来取得网页内容。可是有一个问题出现了。当时用的方法是同步操作，如果我其中的一个IP或是在进行转化的过程中，出现了问题，
哪么这个程序就会停下来，当然了，有的朋友可能会说，用try...catch也可以啊。因为我是循环取值，所以在catch里加一个continue就
行了。可是以前没有搞过异步操作，所以想用这个机会搞一下。就看了一下。
这一看不要紧，搞得我一头雾水。上网上去问，大家给出的方法都是用多线程来搞定。这个在下一个帖子中我会发上来。这里主要说一下用BeginGetResponse，EndGetResponse来完成异步操作。
先说一下，我的要求：
一，从数据库中取出所有的IP
二，利用httpwebrequest的post方法在网上取得它的相应地址。当然了，是用post还是用get主要是看网上的网站是用什么方法来传值。
三，将所得到的值写入数据库

下面我把我的代码放上来，前台没有什么东西，运行的结果是直接写入数据库，
数据库名为DBCT_Dev
省份表S_Province，其中ProvinceName为省分名。ProvinceCode为省分相对的Code
市级表S_City,其中CityName为市名。ZipCode为市相对应的Code。
这二个表是在网上找到的，有很多中国省市关联表，大家可以去下一个。
用户IP表UserCode，其中Code为其IP所对应的省市Code，IP为用户的IP地址。

好了，下面是代码

下面的是周公在CSDN上一个帖子上给出的代码是用BeginGetRequestStream，GetResponseStream来完成的

1. using System;
2. using System.Net;
3. using System.IO;
4. using System.Text;
5. using System.Threading;
7. class HttpWebRequestBeginGetRequest
8. {
9.     public static ManualResetEvent allDone = new ManualResetEvent(false);
10.     public static void Main()
11.     {
12.         
14.             // Create a new HttpWebRequest object.
15.             HttpWebRequest request=(HttpWebRequest) WebRequest.Create("http://www.contoso.com/example.aspx");    
16.     
17.             // Set the ContentType property. 
18.             request.ContentType="application/x-www-form-urlencoded";
19.             // Set the Method property to 'POST' to post data to the URI.
20.             request.Method = "POST";
21.             // Start the asynchronous operation.    
22.             request.BeginGetRequestStream(new AsyncCallback(ReadCallback), request);    
23.             
24.             // Keep the main thread from continuing while the asynchronous
25.             // operation completes. A real world application
26.             // could do something useful such as updating its user interface. 
27.             allDone.WaitOne();
29.             // Get the response.
30.             HttpWebResponse response = (HttpWebResponse)request.GetResponse();
31.             Stream streamResponse = response.GetResponseStream();
32.             StreamReader streamRead = new StreamReader(streamResponse);
33.             string responseString = streamRead.ReadToEnd();
34.             Console.WriteLine(responseString);
35.             // Close the stream object.
36.             streamResponse.Close();
37.             streamRead.Close();
38.     
39.             // Release the HttpWebResponse.
40.             response.Close();
41.         }
42.     
43.     private static void ReadCallback(IAsyncResult asynchronousResult)
44.     {    
45.             HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
46.             // End the operation.
47.             Stream postStream = request.EndGetRequestStream(asynchronousResult);
48.             Console.WriteLine("Please enter the input data to be posted:");
49.             string postData = Console.ReadLine ();
50.             
51.             // Convert the string into a byte array.
52.             byte[] byteArray = Encoding.UTF8.GetBytes(postData);
53.             // Write to the request stream.
54.             postStream.Write(byteArray, 0, postData.Length);
55.             postStream.Close ();
56.             allDone.Set();    
57.     }
59. }
60. ----------------------------------------------------------------------------------------------------------

61. C# HttpWebRequest异步

    人气:44  分类: C#编程 来源:互联网

    ----------------------------Un Test------------------------- using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Net; using System.Threading; using System.IO; namespace WebReqHtml {     internal class WebReqState     {         public byte[] Buffer;         public MemoryStream ms;         public const int BufferSize = 1024;         public Stream OrginalStream;         public HttpWebResponse WebResponse;              public WebReqState()         {             Buffer = new byte[1024];             ms = new MemoryStream();         }     }     public delegate  void  ReadDataComplectedEventHandler(byte[] data);     class HtmlFromWebReq     {         private Uri url;         public event ReadDataComplectedEventHandler OnReadDataComplected;         public HtmlFromWebReq(string absoluteUrl)         {             url = new Uri(absoluteUrl);         }         protected void readDataCallback(IAsyncResult ar)         {             WebReqState rs = ar.AsyncState as WebReqState;             int read = rs.OrginalStream.EndRead(ar);             if (read > 0)             {                 rs.ms.Write(rs.Buffer, 0, read);                 rs.OrginalStream.BeginRead(rs.Buffer, 0, WebReqState.BufferSize, new AsyncCallback(readDataCallback), rs);             }             else             {                 rs.OrginalStream.Close();                 rs.WebResponse.Close();                 if (OnReadDataComplected != null)                 {                     OnReadDataComplected(rs.ms.ToArray());                 }             }         }         protected void responseCallback(IAsyncResult ar)         {             HttpWebRequest req = ar.AsyncState as HttpWebRequest;             if (req == null)                 return;             HttpWebResponse response = req.EndGetResponse(ar) as HttpWebResponse;             if (response.StatusCode!= HttpStatusCode.OK)             {                 response.Close();                 return;             }             WebReqState st=new WebReqState();             st.WebResponse = response;             Stream repsonseStream = response.GetResponseStream();             st.OrginalStream = repsonseStream;             repsonseStream.BeginRead(st.Buffer, 0, WebReqState.BufferSize, new AsyncCallback(readDataCallback), st);         }         public void BeginCreateHtml()         {             HttpWebRequest req = HttpWebRequest.Create(url.AbsoluteUri) as HttpWebRequest;             req.BeginGetResponse( new AsyncCallback(responseCallback), req);                      }               } }