使用HttpWebRequest POST数据到服务器上

HTTP协议中，向服务器传递参数的几个位置是： HTTP Header / GET的字符串 / POST中间的Body
下面的示例代码演示如何简单的POST数据到服务器.

//  发送请求
string  requestBody  =   string .Format( " {0}={1}&{2}={3}&{4}={5}&{6}={7}&{8}={9} "
    , HttpUtility.UrlEncode( " version_id " , Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode(m_VersionNo, Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode( " merchant_id " , Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode(m_MerchantID, Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode( " verifystring " , Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode(hashStr.ToString().ToLower(), Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode( " order_date " , Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode(m_OrderDate, Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode( " order_id " , Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode(m_OrderID, Encoding.GetEncoding( " GB2312 " ))
    , HttpUtility.UrlEncode( " retmode " , Encoding.GetEncoding( " GB2312 " ))
    ,  string .Empty
    );

HttpWebRequest request  =  (HttpWebRequest)HttpWebRequest.Create(m_GatewayURL);
request.Method  =   " POST " ;
request.KeepAlive  =   false ;
request.ContentType  =   " application/x-www-form-urlencoded " ;
byte [] aryBuf  =  Encoding.GetEncoding( " GB2312 " ).GetBytes(requestBody);
request.ContentLength  =  aryBuf.Length;
using (Stream writer  =  request.GetRequestStream())
{
    writer.Write(aryBuf, 0, aryBuf.Length);
    writer.Close();
    writer.Dispose();
}
string  ret  =   string .Empty;
using  (WebResponse response  =  request.GetResponse())
{
    StreamReader reader = new StreamReader( response.GetResponseStream()
        , Encoding.GetEncoding("GB2312")
        );   
    ret = reader.ReadToEnd();
    reader.Close();
    reader.Dispose();
}