DirectoryEntry objDE = new DirectoryEntry("LDAP://" + domain, username, password, AuthenticationTypes.Secure);
            string strFilter = "(&(objectCategory=group)(objectClass=group))";
            DirectorySearcher objSearcher = new DirectorySearcher(objDE, strFilter);
            //排序  
            objSearcher.Sort = new SortOption("name", SortDirection.Ascending);
            SearchResultCollection src = objSearcher.FindAll();

            foreach (SearchResult sr in src)
            {
                DirectoryEntry myde = sr.GetDirectoryEntry();
                var strGuid = myde.Guid.ToString();//用户Guid，创建用户时由系统自动生成  
                var strParentGuid = myde.Parent.Guid.ToString();//用户所在组织单元的Guid  
                myde.Properties["name"][0].ToString();//用户名称  
                var node = new TreeViewItem() { Header = myde.Name + "-" + myde.SchemaClassName };
                FillProperty(myde, node);
                this.tvAccount.Items.Add(node);
            }