public class GwBasePage : System.Web.UI.Page
{
    public GwBasePage()
    {
        //
        //TODO: 在此处添加构造函数逻辑
        //
    }

    /// <summary>
    /// 重写页面加载事件
    /// </summary>
    /// <param name="e"></param>
    protected override void OnLoad(EventArgs e)
    {
        if (CurrentUser == null)
        {
            GoAdminLoginPage();
        }
        base.OnLoad(e);
    }

    /// <summary>
    /// 跳转到登陆页并停止操作
    /// </summary>
    protected void GoAdminLoginPage()
    {
        Response.Write("<script>top.location='Login.aspx';</script>");
        Response.End();
    }

    /// <summary>
    /// 得到当前登陆用户
    /// </summary> 
    public CN_T_Admin CurrentUser
    {
        get
        {
            return Session["GWUser"] as CN_T_Admin;
        }
    }

    /// <summary>
    /// 截取字符串长度
}

需要判断的继承:

public partial class Admin_GW_T_UserLoginIDEdit : GwBasePage