C#中HttpWebRequest的用法详解

2020-01-24 02:17:51

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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 //www.VeVB.COm/?hl=zh-CN 中，前面部分 //www.VeVB.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：

复制代码代码如下:

HttpWebRequest req = (HttpWebRequest) HttpWebRequest.Create( "//www.VeVB.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：

复制代码代码如下:

Encoding myEncoding = Encoding.GetEncoding("gb2312");
string address = "//www.VeVB.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 //www.VeVB.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：

复制代码代码如下:

string param = "hl=zh-CN&newwindow=1";
byte[] bs = Encoding.ASCII.GetBytes(param);
HttpWebRequest req = (HttpWebRequest) HttpWebRequest.Create( "//www.VeVB.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 //www.VeVB.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：

复制代码代码如下:

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( "//www.VeVB.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

复制代码代码如下:

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;
        }
   }
}