List<T>转为Json格式

public class Shop

   {
        public string Name { get; set; }

        public string ShopID { get; set; }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        List<Shop> lst = new List<Shop>() {
        new Shop(){Name="北京",ShopID="33"},
        new Shop(){Name="上海",ShopID="823"}
        };

        WriteString(lst);
    }


 public static void WriteString(List<Shop_Item> lst_shop)
        {
            StringBuilder Json = new StringBuilder();
            Json.Append("[");
            if (lst_shop.Count > 0)
            {
                for (int i = 0; i < lst_shop.Count; i++)
                {
                    Json.Append("{");
                    Json.AppendFormat("\"Name\":\"{0}\",", lst_shop[i].Name);
                    Json.AppendFormat("\"ShopID\":\"{0}\"", lst_shop[i].ShopID);
                    Json.Append("}");
                    if (i < lst_shop.Count - 1)
                    {
                        Json.Append(",");
                    }
                }
            }
            Json.Append("]");

            HttpContext.Current.Response.ContentType = "text/plain";
            HttpContext.Current.Response.Write(Json.ToString());
            //HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.End(); ;
        }