.net WebClient发送请求实例：

public static Main(string [] ager)
{
     WebClient client = new WebClient();
            client.Headers.Clear();
            client.Headers.Add("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
            client.Encoding = Encoding.UTF8;
            string responseStr = client.UploadString("Http://192.168.1.22/ensms.ashx", "POST", "action=" + action + "&userid=" + userid + "&account=" + account + "&password=" + password + "&mobile=" + mobile + "&content=" + content + "&sendTime=" + sendTime + "&extno=" + extno);
            context.Response.Write(responseStr);
}