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 //www.jb51.net/?hl=zh-cn 中，前面部分 //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( "//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 = "//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 //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( "//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 //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( "//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。