csharp: DataRelation objects to represent a parent/child/Level relationship

 /// <summary>
        ///
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Page_Load(object sender, EventArgs e)
        {

            var sections = new List<Section>
            {
                new Section { Id = 1, Name = "中国", ParentID = 0 },
                new Section { Id = 2, Name = "江西", ParentID = 1 },
                new Section { Id = 3, Name = "江苏", ParentID = 1 },
                new Section { Id = 4, Name = "南京", ParentID = 3 },
                new Section { Id = 5, Name = "南昌", ParentID = 2 },
                new Section { Id = 6, Name = "东湖区", ParentID = 5 },
                new Section { Id = 7, Name = "广东", ParentID = 1 },
                new Section { Id = 8, Name = "深圳", ParentID = 7 },
                new Section { Id = 9, Name = "罗湖区涂聚文", ParentID = 8 }
            };

            //sections = sections.OrderBy(x => x.ParentID).ThenBy(x => x.Name).ToList();
            //var stack = new Stack<Section>();

            //// Grab all the items without parents
            //foreach (var section in sections.Where(x => x.ParentID == default(int)).Reverse())
            //{
            //    stack.Push(section);
            //    sections.RemoveAt(0);
            //}

            var output = new List<Section>();
            //while (stack.Any())
            //{
            //    var currentSection = stack.Pop();

            //    var children = sections.Where(x => x.ParentID == currentSection.Id).Reverse();

            //    foreach (var section in children)
            //    {
            //        stack.Push(section);
            //        sections.Remove(section);
            //    }
            //    output.Add(currentSection);
            //}
            //sections = output;

            List<MySection> mys = MenuHelper.GetMyMenuCollection(sections);

            //ResolveDDL<MySectionMenu>(mys);
            var outputlist = (from mysection in mys orderby mysection.TreeLevel descending select mysection).ToList();
            var outputstringlist = (from mysection in mys orderby mysection.TreeLevel descending select mysection.Name).ToList();

            for (int i = 0; i < outputlist.Count; i++)
            {

                //Response.Write(string.Format("ID:{0} ParentID: {1} TreeLevel: {2} Name:{3}<br/>", mys[i].Id, mys[i].ParentID, mys[i].TreeLevel,mys[i].Name));
                Response.Write(string.Format("ID:{0} ParentID: {1} TreeLevel: {2} Name:{3}<br/>", outputlist[i].Id, outputlist[i].ParentID, outputlist[i].TreeLevel, outputlist[i].Name));
            }

        }

        /// <summary>
        ///
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="mys"></param>
        protected void ResolveDDL<T>(List<T> mys) where T : MyBaseSection, new()
        {

            ResolveDDL<T>(mys, -1, true);
        }
        /// <summary>
        ///
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="mys"></param>
        /// <param name="currentId"></param>
        protected void ResolveDDL<T>(List<T> mys, int currentId) where T : MyBaseSection, new()
        {
            ResolveDDL<T>(mys, currentId, true);
        }

        /// <summary>
        /// 将一个树型结构放在一个下列列表中可供选择
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="currentId"></param>
        /// <param name="mys"></param>
        protected void ResolveDDL<T>(List<T> mys, int currentId, bool addRootNode) where T : MyBaseSection, new()
        {
            if (addRootNode)
            {
                // 所有节点的TreeLevel加一，然后添加根节点
                foreach (T my in mys)
                {
                    my.TreeLevel += 1;
                }
                T root = new T();
                root.Name = "--根节点--";
                root.Id = 0;
                root.TreeLevel = 0;
                mys.Insert(0, root);
            }

            // currentId==-1表示当前节点不存在
            if (currentId != -1)
            {
                // 本节点不可点击（也就是说当前节点不可能是当前节点的父节点）
                // 并且本节点的所有子节点也不可点击，你想如果当前节点跑到子节点的子节点，那么这些子节点就从树上消失了
                bool startChileNode = false;
                int startTreeLevel = 0;
                foreach (T my in mys)
                {
                    if (my.Id == currentId)
                    {
                        startTreeLevel = my.TreeLevel;
                        my.Enabled = false;
                        startChileNode = true;
                    }
                    else
                    {
                        if (startChileNode)
                        {
                            if (my.TreeLevel > startTreeLevel)
                            {
                                my.Enabled = false;
                            }
                            else
                            {
                                startChileNode = false;
                            }
                        }
                    }
                }
            }
        }

    }

    /// <summary>
    /// /
    /// </summary>
    public class Section
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int ParentID { get; set; }
    }
    /// <summary>
    ///
    /// </summary>
    public class MySection
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int ParentID { get; set; }
        public int TreeLevel { get; set; }
    }
    /// <summary>
    ///
    /// </summary>
    public class MySectionMenu : MyBaseSection
    {

    }
    /// <summary>
    ///
    /// </summary>
    public class MyBaseSection
    {
         public int Id
        {
            get;
            set;
        }

        public int ParentId
        {
            get;
            set;
        }

        public string Name
        {
            get;
            set;
        }
                /// <summary>
        /// 本菜单在树形结构中层级（从0开始）
        /// </summary>
        public int TreeLevel
        {
            get;
            set;
        }

        /// <summary>
        /// 是否可用（默认true）
        /// </summary>
        public bool Enabled
        {
            get;
            set;
        }

        /// <summary>
        /// 是否叶子节点（默认false）
        /// </summary>
        public bool IsTreeLeaf
        {
            get;
            set;
        }

    }

    /// <summary>
    ///
    /// </summary>
    public class MenuHelper
    {

        /// <summary>
        ///
        /// </summary>
        /// <param name="oldMenus"></param>
        /// <returns></returns>
        public static List<MySection> GetMyMenuCollection(List<Section> oldMenus)
        {
            List<MySection> newMenus = new List<MySection>();
            ResolveMenuCollection(oldMenus, newMenus, 0, 0);

            return newMenus;
        }
        /// <summary>
        ///
        /// </summary>
        /// <param name="oldMenus"></param>
        /// <param name="newMenus"></param>
        /// <param name="parentId"></param>
        /// <param name="level"></param>
        /// <returns></returns>
        private static int ResolveMenuCollection(List<Section> oldMenus, List<MySection> newMenus, int parentId, int level)
        {
            int count = 0;
            foreach (Section menu in oldMenus)
            {
                if (menu.ParentID == parentId)
                {
                    count++;

                    MySection my = new MySection();
                    newMenus.Add(my);
                    my.TreeLevel = level;
                    my.Id = menu.Id;
                    my.Name = menu.Name;
                    my.ParentID = menu.ParentID;       

                    level++;
                    int childCount = ResolveMenuCollection(oldMenus, newMenus, menu.Id, level);
                    level--;
                }
            }

            return count;
        }
    }

　　

显示结果：

ID:1 ParentID: 0 TreeLevel: 0 Name:中国
ID:2 ParentID: 1 TreeLevel: 1 Name:江西
ID:5 ParentID: 2 TreeLevel: 2 Name:南昌
ID:6 ParentID: 5 TreeLevel: 3 Name:东湖区
ID:3 ParentID: 1 TreeLevel: 1 Name:江苏
ID:4 ParentID: 3 TreeLevel: 2 Name:南京
ID:7 ParentID: 1 TreeLevel: 1 Name:广东
ID:8 ParentID: 7 TreeLevel: 2 Name:深圳
ID:9 ParentID: 8 TreeLevel: 3 Name:涂聚文