给一个网址传递参数，并接收返回的参数

 public  string SendMsg(string user,string password,string phone,string text)
    {
        try
        {
            //if (!Regex.IsMatch(phone, @"^(13|15)\d{9}$"))
            //    return "手机号码格式错误！";
            string url = "http://www.xunsai.net:8000/";
            string param = "user=" + user+ "&password=" + password + "&phonenumber=" + phone + "&text=" + text + "&charset=gb2312";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "POST";
            request.AllowAutoRedirect = true;
            request.ContentType = "text/html;charset=GB2312;";

            NetworkCredential nc = new NetworkCredential(user, password);
            request.Credentials = nc;

            byte[] data = Encoding.GetEncoding("GB2312").GetBytes(param);
            request.ContentLength = data.Length;
            Stream stream = request.GetRequestStream();
            stream.Write(data, 0, data.Length);
            stream.Close();
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("GB2312"));
            string s = sr.ReadToEnd();
            response.Close();
            return s;
        }
        catch(Exception e)
        {
            return e.Message;
        }
    }

 

 

    protected void Button1_Click(object sender, EventArgs e)
    {
        //把下面 的那些 string.Empty 按备注换掉你需要的即可
    string url = string.Format(
        "http://bms.hichina.com/sms_gateway/sms_api?"
        + "user_id={0}&password={1}&mobile_phone={2}"  
        +"&msg={3}&send_date={4}&subCode={5}"
    , string.Empty //用户id
    , string.Empty //密码
    , string.Empty //电话号码
    , Server.UrlEncode( string.Empty ) //短信消息
    , Server.UrlEncode( string.Empty ) //发送日期
    , string.Empty //企业号
    );
    System.Net.WebClient client = new System.Net.WebClient ();


    string reply = client.DownloadString(url);

    Label1.Text = reply;


    }