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[ASP.net教程]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