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 https://www.nhooo.com/?hl=zh-CN 中，前面部分 https://www.nhooo.com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( "https://www.nhooo.com?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 = "https://www.nhooo.com/?" + 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 https://www.nhooo.com ，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( "https://www.nhooo.com/" );

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 https://www.nhooo.com 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( "https://www.nhooo.com/" );

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。