sharepoint中库读取字段

        /// <summary>
        /// 得到图片新闻的类型
        /// </summary>
        /// <returns></returns>
        public List<string> GetAllTypes()
        {
            List<string> listAll = new List<string>();
            SPSite site = null;
            SPWeb web = null;
            Guid guid = SPContext.Current.Site.ID;
            try
            {
                SPSecurity.RunWithElevatedPrivileges(delegate()
                {
                    site = new SPSite(guid);
                    web = site.OpenWeb();

                    SPList list = web.Lists[ListNameConfiguration.PictureNews];
                    SPListItemCollection listItems = list.Items;
                    SPFieldChoice spf = (SPFieldChoice)list.Fields["类别"];

                    foreach (string sf in spf.Choices)
                    {
                        listAll.Add(sf);
                    }

                });

                return listAll;
            }
            catch (Exception ex)
            {

                return null;
            }
            finally
            {
                if (web != null) { web.Dispose(); }
                if (site != null) { site.Dispose(); }
            }

        }