C#中HttpWebRequest的用法详解

本文实例讲述了C#中HttpWebRequest的用法。分享给大家供大家参考。具体如下：

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;        }   }}

希望本文所述对大家的C#程序设计有所帮助。

原文地址：http://www.jb51.net/article/57156.htm