MVC 生成Html字符串MvcHtmlString CacheHelper用法

 <div class="nav">
        @Html.BuildNav(userInfo.UserID)
        <div class="clear">

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Security.Principal;
using System.Text;
using System.Web.Mvc;

namespace MFK.HTML
{
    public static class HTMLBuildControl
    {
        /// <summary>
        /// 生成一级导航链接
        /// </summary>
        /// <param name="helper"></param>
        /// <param name="userID">用户编号</param>
        /// <returns></returns>
        public static MvcHtmlString BuildNav(this HtmlHelper helper,int userID)
        {
            string key = string.Intern("UserNav_" + Current.UserName);
            if (CacheHelper.IsExist(key))
            {
                return MvcHtmlString.Create(CacheHelper.Get(key).ToString());
            }
            else
            {
                List<ddd> list = BLLModel.GetControllist(userID);
                StringBuilder html = new StringBuilder();
                html.Append("<ul>");
                  for (int i = 0; i < list.Count; i++)
                {
                    html.Append(<li>list.name</li>));
                }
                html.Append("</ul>");
                CacheHelper.Add(key, html.ToString());
                return MvcHtmlString.Create(html.ToString());
            }
            
        }
}
}