使用post向webservice发送请求，并且返回值

注意，这个方法仅仅适用于:该post页面处于websercive 站点下，或者是与webservice同属于一个主站点，即在iis里属于同一主站点的同级虚拟目录。

 protected void btnSynData_Click(object sender, EventArgs e)
        {
string wsUrl = "http://127.0.0.1:1113/yingxiao/clfbxd.asmx/huixie";
//注意：huixie 是webservice的方法名


  string postData = "我是谁";
    HttpConnectToServer(wsUrl, postData);

}

 /// <summary>
        /// 发送消息到ws服务器
        /// </summary>
        /// <param name="ServerPage"></param>
        /// <param name="strXml"></param>
        /// <returns></returns>
        public string HttpConnectToServer(string ServerPage, string strXml)
        {
            string postData = "strXml=" + strXml;

            byte[] dataArray = Encoding.Default.GetBytes(postData);
            //创建请求
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(ServerPage);
            request.Credentials = CredentialCache.DefaultCredentials;
            request.CookieContainer = new CookieContainer();
            request.Method = "POST";
            request.ContentLength = dataArray.Length;
            request.ContentType = "application/x-www-form-urlencoded";
            //创建输入流
            Stream dataStream = null;
            try
            {
                dataStream = request.GetRequestStream();
            }
            catch (Exception)
            {
                return null;//连接服务器失败
            }

            //发送请求
            dataStream.Write(dataArray, 0, dataArray.Length);
            dataStream.Close();
            //读取返回消息
            string res = string.Empty;
            try
            {
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                res = reader.ReadToEnd();
                reader.Close();
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }

            return res;
        }

参考：http://www.jb51.net/article/34589.htm