private void btnLogin_Click(object sender, EventArgs e)
        {
            Jid jid = new Jid(txtJid.Text);   //用户名@服务器名
            conn.Username = jid.User;          
            conn.Server = jid.Server;
            conn.Password = txtPassword.Text;
            conn.Port = 5222;
            conn.UseCompression = false;                    
            conn.KeepAlive = true;
            conn.AutoRoster = true;             
            conn.AutoPresence = true;           
            conn.UseStartTLS = true;           
            conn.AutoResolveConnectServer = false;
            conn.ConnectServer = "localhost";
            this.DialogResult = DialogResult.OK;
            this.Close();
        }