向目标URL发起post

using System.IO;
using Systme.Text;
using System.Net;

  protected string GetWebContent(string url)
        {
            Stream outstream = null;
            Stream instream = null;
            StreamReader sr = null;
            HttpWebResponse response = null;
            HttpWebRequest request = null;
            // 要注意的这是这个编码方式，还有内容的Xml内容的编码方式
            Encoding encoding = Encoding.GetEncoding("GBK");
            byte[] data = encoding.GetBytes(url);

            // 准备请求,设置参数
            request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "POST";
            //request.ContentType = "text/plain";
            request.ContentLength = data.Length;

            outstream = request.GetRequestStream();
            outstream.Write(data, 0, data.Length);
            outstream.Flush();
            outstream.Close();
            //发送请求并获取相应回应数据

            response = request.GetResponse() as HttpWebResponse;
            //直到request.GetResponse()程序才开始向目标网页发送Post请求
            instream = response.GetResponseStream();