lambda建树方法

           List<E_Department> totalItems = (List<E_Department>)B_Department.Instance.Get_DepartmentList(slr);
           Action<E_Department> SetChildren = null;
           //封装一个方法(递归)不断读取树的分支
           SetChildren = Parent =>
           {
               Parent.Children = totalItems.FindAll(childItem => childItem.ParentGuid == Parent.Guid);
               Parent.Children.ForEach(SetChildren);
           };
           //初始化树列表
           List<E_Department> treeItems = totalItems.FindAll(parentItem => parentItem.ParentGuid == "");
           treeItems.ForEach(SetChildren);
           return treeItems;