C#中HttpWebRequest的用法详解

HttpWebRequest类主要利用HTTP 协议和服务器交互，通常是通过 GET 和 POST 两种方式来对数据进行获取和提交。下面对这两种方式进行一下说明：

GET 方式：
GET 方式通过在网络地址附加参数来完成数据的提交，比如在地址 http://www.jb51.net/?hl=zh-CN 中，前面部分 http://www.jb51.net表示数据提交的网址，后面部分 hl=zh-CN 表示附加的参数，其中 hl 表示一个键(key)， zh-CN 表示这个键对应的值(value)。
程序代码如下：

HttpWebRequest req = (HttpWebRequest) HttpWebRequest.Create( "http://www.jb51.net?hl=zh-CN" );
req.Method = "GET";
using (WebResponse wr = req.GetResponse())
{
//在这里对接收到的页面内容进行处理
}

使用 GET 方式提交中文数据。

GET 方式通过在网络地址中附加参数来完成数据提交，对于中文的编码，常用的有 gb2312 和 utf8 两种。
用 gb2312 方式编码访问的程序代码如下：

Encoding myEncoding = Encoding.GetEncoding("gb2312");
string address = "http://www.jb51.net/?" + HttpUtility.UrlEncode("参数一", myEncoding) + "=" + HttpUtility.UrlEncode("值一", myEncoding);
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(address);
req.Method = "GET";
using (WebResponse wr = req.GetResponse())
{
//在这里对接收到的页面内容进行处理
}

在上面的程序代码中，我们以 GET 方式访问了网址 http://www.jb51.net ，传递了参数“参数一=值一”，由于无法告知对方提交数据的编码类型，所以编码方式要以对方的网站为标准。

POST 方式：

POST 方式通过在页面内容中填写参数的方法来完成数据的提交，参数的格式和 GET 方式一样，是类似于 hl=zh-CN&newwindow=1 这样的结构。
程序代码如下：

string param = "hl=zh-CN&newwindow=1";
byte[] bs = Encoding.ASCII.GetBytes(param);
HttpWebRequest req = (HttpWebRequest) HttpWebRequest.Create( "http://www.jb51.net/" );
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
req.ContentLength = bs.Length;
using (Stream reqStream = req.GetRequestStream())
{
reqStream.Write(bs, 0, bs.Length);
}
using (WebResponse wr = req.GetResponse())
{
//在这里对接收到的页面内容进行处理
}

在上面的代码中，我们访问了 http://www.jb51.net 的网址，分别以 GET 和 POST 方式提交了数据，并接收了返回的页面内容。然而，如果提交的参数中含有中文，那么这样的处理是不够的，需要对其进行编码，让对方网站能够识别。
使用 POST 方式提交中文数据
POST 方式通过在页面内容中填写参数的方法来完成数据的提交，由于提交的参数中可以说明使用的编码方式，所以理论上能获得更大的兼容性。
用 gb2312 方式编码访问的程序代码如下：

Encoding myEncoding = Encoding.GetEncoding("gb2312");
string param = HttpUtility.UrlEncode("参数一", myEncoding) + "=" + HttpUtility.UrlEncode("值一", myEncoding) + "&" + HttpUtility.UrlEncode("参数二", myEncoding) + "=" + HttpUtility.UrlEncode("值二", myEncoding);
byte[] postBytes = Encoding.ASCII.GetBytes(param);
HttpWebRequest req = (HttpWebRequest) HttpWebRequest.Create( "http://www.jb51.net/" );
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded;charset=gb2312";
req.ContentLength = postBytes.Length;
using (Stream reqStream = req.GetRequestStream())
{
reqStream.Write(bs, 0, bs.Length);
}
using (WebResponse wr = req.GetResponse())
{
//在这里对接收到的页面内容进行处理
}

从上面的代码可以看出， POST 中文数据的时候，先使用 UrlEncode 方法将中文字符转换为编码后的 ASCII 码，然后提交到服务器，提交的时候可以说明编码的方式，用来使对方服务器能够正确的解析。
用C#语言写的关于HttpWebRequest 类的使用方法

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;
namespace HttpWeb
{
/// <summary>
///  Http操作类
/// </summary>
public static class httptest
{
/// <summary>
///  获取网址HTML
/// </summary>
/// <param name="URL">网址 </param>
/// <returns> </returns>
public static string GetHtml(string URL)
{
WebRequest wrt;
wrt = WebRequest.Create(URL);
wrt.Credentials = CredentialCache.DefaultCredentials;
WebResponse wrp;
wrp = wrt.GetResponse();
string reader = new StreamReader(wrp.GetResponseStream(), Encoding.GetEncoding("gb2312")).ReadToEnd();
try
{
wrt.GetResponse().Close();
}
catch (WebException ex)
{
throw ex;
}
return reader;
}
/// <summary>
/// 获取网站cookie
/// </summary>
/// <param name="URL">网址 </param>
/// <param name="cookie">cookie </param>
/// <returns> </returns>
public static string GetHtml(string URL, out string cookie)
{
WebRequest wrt;
wrt = WebRequest.Create(URL);
wrt.Credentials = CredentialCache.DefaultCredentials;
WebResponse wrp;
wrp = wrt.GetResponse();
string html = new StreamReader(wrp.GetResponseStream(), Encoding.GetEncoding("gb2312")).ReadToEnd();
try
{
wrt.GetResponse().Close();
}
catch (WebException ex)
{
throw ex;
}
cookie = wrp.Headers.Get("Set-Cookie");
return html;
}
public static string GetHtml(string URL, string postData, string cookie, out string header, string server)
{
return GetHtml(server, URL, postData, cookie, out header);
}
public static string GetHtml(string server, string URL, string postData, string cookie, out string header)
{
byte[] byteRequest = Encoding.GetEncoding("gb2312").GetBytes(postData);
return GetHtml(server, URL, byteRequest, cookie, out header);
}
public static string GetHtml(string server, string URL, byte[] byteRequest, string cookie, out string header)
{
byte[] bytes = GetHtmlByBytes(server, URL, byteRequest, cookie, out header);
Stream getStream = new MemoryStream(bytes);
StreamReader streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
string getString = streamReader.ReadToEnd();
streamReader.Close();
getStream.Close();
return getString;
}
/// <summary>
/// Post模式浏览
/// </summary>
/// <param name="server">服务器地址 </param>
/// <param name="URL">网址 </param>
/// <param name="byteRequest">流 </param>
/// <param name="cookie">cookie </param>
/// <param name="header">句柄 </param>
/// <returns> </returns>
public static byte[] GetHtmlByBytes(string server, string URL, byte[] byteRequest, string cookie, out string header)
{
long contentLength;
HttpWebRequest httpWebRequest;
HttpWebResponse webResponse;
Stream getStream;
httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
CookieContainer co = new CookieContainer();
co.SetCookies(new Uri(server), cookie);
httpWebRequest.CookieContainer = co;
httpWebRequest.ContentType = "application/x-www-form-urlencoded";
httpWebRequest.Accept =
"image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
httpWebRequest.Referer = server;
httpWebRequest.UserAgent =
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
httpWebRequest.Method = "Post";
httpWebRequest.ContentLength = byteRequest.Length;
Stream stream;
stream = httpWebRequest.GetRequestStream();
stream.Write(byteRequest, 0, byteRequest.Length);
stream.Close();
webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
header = webResponse.Headers.ToString();
getStream = webResponse.GetResponseStream();
contentLength = webResponse.ContentLength;
byte[] outBytes = new byte[contentLength];
outBytes = ReadFully(getStream);
getStream.Close();
return outBytes;
}
public static byte[] ReadFully(Stream stream)
{
byte[] buffer = new byte[128];
using (MemoryStream ms = new MemoryStream())
{
while (true)
{
int read = stream.Read(buffer, 0, buffer.Length);
if (read <= 0)
return ms.ToArray();
ms.Write(buffer, 0, read);
}
}
}
/// <summary>
/// Get模式
/// </summary>
/// <param name="URL">网址 </param>
/// <param name="cookie">cookies </param>
/// <param name="header">句柄 </param>
/// <param name="server">服务器 </param>
/// <param name="val">服务器 </param>
/// <returns> </returns>
public static string GetHtml(string URL, string cookie, out string header, string server)
{
return GetHtml(URL, cookie, out header, server, "");
}
/// <summary>
/// Get模式浏览
/// </summary>
/// <param name="URL">Get网址 </param>
/// <param name="cookie">cookie </param>
/// <param name="header">句柄 </param>
/// <param name="server">服务器地址 </param>
/// <param name="val"> </param>
/// <returns> </returns>
public static string GetHtml(string URL, string cookie, out string header, string server, string val)
{
HttpWebRequest httpWebRequest;
HttpWebResponse webResponse;
Stream getStream;
StreamReader streamReader;
string getString = "";
httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
httpWebRequest.Accept = "*/*";
httpWebRequest.Referer = server;
CookieContainer co = new CookieContainer();
co.SetCookies(new Uri(server), cookie);
httpWebRequest.CookieContainer = co;
httpWebRequest.UserAgent =
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
httpWebRequest.Method = "GET";
webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
header = webResponse.Headers.ToString();
getStream = webResponse.GetResponseStream();
streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
getString = streamReader.ReadToEnd();
streamReader.Close();
getStream.Close();
return getString;
}
}
}

转： http://www.jb51.net/article/57156.htm