从类型为 人员和组 的字段中取值

从人员和组的字段中取出的值形如  17;#张三;#20;#李四;#33;#王五  ，以下方法将其转换为List<SPPrincipal>

 

        /// <summary>
        /// 从人员和组的集合的字符串表示形式解析出人员和组的集合
         /// </summary>
        /// <param name="web">SPWeb对象</param>
        /// <param name="userString">人员和组的集合的字符串表示形式</param>
        /// <returns>人员和组的集合</returns>
        public static List<SPPrincipal> GetUsers(SPWeb web,string userString)
        { 
            List<SPPrincipal> rtn=new List<SPPrincipal> ();
            if(!string.IsNullOrEmpty (userString ))
            {
                foreach (Match m in Regex.Matches(userString, "(\\d+);#([^;]+)"))
                {
                    int id = int.Parse(m.Groups[1].Value);
               
                    SPUser user=null;
                    foreach (SPUser u in web.SiteUsers)
                    {
                        if (u.ID == id)
                        {
                            user = u;
                            break;
                        }
                    }
                    if (user != null)
                        rtn.Add(user);
                    else
                    {
                        SPGroup group=null;
                        foreach (SPGroup g in web.SiteGroups)
                        {

                            if (g.ID == id)
                            {
                                group = g;
                                break;
                            }
                        }
                        if (group != null)
                            rtn.Add(group);
                    
                    }
                }
            }
        return rtn;
    }