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;

}