//验证用户是否在Application中存在(是否在线) IDictionaryEnumerator e1 = h.GetEnumerator(); bool flag = false; while (e1.MoveNext()) { if (checkCookie(e1.Value.ToString())) { flag = true; break; } } if (flag) { Response.Write("<script defer language='javascript'>alert('This user is online!');history.go(-1);</script>"); } else { loginLogic login = new loginLogic(this.txt_user_id.Text.Trim(), this.txt_password.Text.Trim());