求助，关于asp.net menu控件的三级菜单问题

[深海线]

正在学习nopcommerce 的源码，想加一个导航菜单，用asp.net 自带的MENU来做，参照了nopcomerce论坛的方法，但是
一直无法实现三级菜单。只能显示二级菜单。

using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Text;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using NopSolutions.NopCommerce.BusinessLogic.Categories;
using NopSolutions.NopCommerce.BusinessLogic.Products;
using NopSolutions.NopCommerce.BusinessLogic.SEO;
using NopSolutions.NopCommerce.Common.Utils;
using NopSolutions.NopCommerce.Common.Utils;
using NopSolutions.NopCommerce.BusinessLogic.Media;
using NopSolutions.NopCommerce.BusinessLogic.Configuration.Settings;

namespace NopSolutions.NopCommerce.Web.Modules
{
    // public partial class NavMenu : System.Web.UI.UserControl //BaseNopUserControl
    public partial class NavMenu : BaseNopUserControl
    {
        #region Handlers
        protected void Page_Load(object sender, EventArgs e)
        {
            //------------
        }
        #endregion

        #region Overrides
        protected override void CreateChildControls()
        {

            if (!this.ChildControlsCreated)
            {
                CreateMenu();
                base.CreateChildControls();
                ChildControlsCreated = true;
            }
        }

        #endregion

        #region Utilities
        //Menu NavigationMenu = null;
        protected void CreateMenu()
        {

            MenuItem me = new MenuItem();
          
            NavMenu2.Orientation = Orientation.Vertical;

            List<Category> breadCrumb = null;
            Category currentCategory = CategoryManager.GetAllCategories()[0];
            if (currentCategory != null)
                breadCrumb = CategoryManager.GetBreadCrumb(currentCategory.CategoryId);
             
            else
                breadCrumb = new List<Category>();

            CreateChildMenu(breadCrumb, 0, currentCategory, 0);//创建父菜单
            
            

        }

        MenuItem MainMenuItem = null;
        MenuItem SubMenuItem = null;
        MenuItem threeMenuItem = null;

        protected void CreateChildMenu(List<Category> breadCrumb, int rootCategoryID, Category currentCategory, int level)
        {
            int padding = level++;
            string xie = padding.ToString();
          
            foreach (Category category in CategoryManager.GetAllCategoriesByParentCategoryId(rootCategoryID))
            {
                string URL = SEOHelper.GetCategoryUrl(category.CategoryId);
                string CategoryName = Server.HtmlEncode(category.Name);
                string ImgURL = PictureManager.GetPictureUrl(category.PictureId, SettingManager.GetSettingValueInteger
                   ("Media.Category.ThumbnailImageSize", 15), false);
                if (padding > 0)
                {                  
                    //SubMenu
                   SubMenuItem = CreateMenuItem(CategoryName, URL, CategoryName);
                    // Add the submenu items to the ChildItems
                    // 收集根菜单项。
                    MainMenuItem.ChildItems.Add(SubMenuItem);
                    // SecondNode.ChildNodes.Add(SubMenuItem); 
                   
                }
                else
                { //MainMenu
                    MainMenuItem = CreateMenuItem(category.Name, URL, CategoryName, ImgURL);
                    NavMenu2.Items.Add(MainMenuItem);
                    //NavigationMenu.
                    // TV.Nodes.Add(FirestNode);
                }
               
               for (int i = 0; i <= breadCrumb.Count-1; i++)
                    
        
                    CreateChildMenu(breadCrumb, category.CategoryId, currentCategory, level);

               string ll = category.CategoryId.ToString();
      
                    Label2.Text =ll;
              
               
            }
                     //phCategories.Controls.Add(NavigationMenu);
        }

        MenuItem CreateMenuItem(String text, String url, String toolTip, String ImageUrl)
        {
            //创建一个新的MenuItem对象
            MenuItem mainMenuItem = new MenuItem();
            // 设置菜单项属性的对象使用
            // 指定参数
            mainMenuItem.Text = text;
            mainMenuItem.NavigateUrl = url;
            mainMenuItem.ToolTip = toolTip;
            // menuItem.ImageUrl = ImageUrl;
            mainMenuItem.PopOutImageUrl = ImageUrl;
            mainMenuItem.Value = text;
            return mainMenuItem;
            
        }

        MenuItem CreateMenuItem(String text, String url, String toolTip)
        {
            // Create a new MenuItem object.
            MenuItem SubMenuItem = new MenuItem();
            // 设置MenuItem的对象使用的属性
            // the specified parameters.
            SubMenuItem.Text = text;
            SubMenuItem.NavigateUrl = url;
            SubMenuItem.ToolTip = toolTip;
            // menuItem.ImageUrl = ImageUrl;
            SubMenuItem.Value = text;
            return SubMenuItem;
        }
        MenuItem CreateMenuItem(String text, String url)
        {
            // Create a new MenuItem object.
            MenuItem threeMenuItem = new MenuItem();
            // 设置MenuItem的对象使用的属性
            // the specified parameters.
            threeMenuItem.Text = text;
            threeMenuItem.NavigateUrl = url;
           // threeMenuItem.ToolTip = toolTip;
            // menuItem.ImageUrl = ImageUrl;
            threeMenuItem.Value = text;
            return threeMenuItem;
        }
    }
}
        #endregion

[深海线]

给出另一个类的源码，从供分析用。

        /// <summary>
        /// Gets all categories获取所有分类
        /// 获取所有分类
        /// </summary>
        /// <returns>Categories</returns>
        public static List<Category> GetAllCategories()
        {
            bool showHidden = NopContext.Current.IsAdmin;
            return GetAllCategories(showHidden);
        }


        /// <summary>
        /// Gets all categories
        /// 获取所有分类
        /// </summary>
        /// <param name="showHidden">A value indicating whether to show hidden records一个值，指示是否显示隐藏的记录</param>
        /// <returns>Categories</returns>
        public static List<Category> GetAllCategories(bool showHidden)
        {
            var context = ObjectContextHelper.CurrentObjectContext;
            var query = from c in context.Categories
                        orderby c.ParentCategoryId, c.DisplayOrder
                        where (showHidden || c.Published) &&
                        !c.Deleted
                        select c;
            var unsortedCategories = query.ToList();

            //sort categories
            //TODO sort categories on database layer
            var sortedCategories = unsortedCategories.SortCategoriesForTree(0);

            return sortedCategories;
        }
        
        /// <summary>
        /// Gets all categories by parent category identifier
        /// 获取所有类别的父类别标识
        /// </summary>
        /// <param name="parentCategoryId">Parent category identifier</param>
        /// <returns>Category collection</returns>
        public static List<Category> GetAllCategoriesByParentCategoryId(int parentCategoryId)
        {
            bool showHidden = NopContext.Current.IsAdmin;
            return GetAllCategoriesByParentCategoryId(parentCategoryId, showHidden);
        }
        
        /// <summary>
        /// Gets all categories filtered by parent category identifier
        /// 获取由父类所有类别过滤标识符
        /// </summary>
        /// <param name="parentCategoryId">Parent category identifier |父类标识符</param>
        /// <param name="showHidden">A value indicating whether to show hidden records</param>
        /// <returns>Category collection|分类集合</returns>
        public static List<Category> GetAllCategoriesByParentCategoryId(int parentCategoryId,
            bool showHidden)
        {
            var context = ObjectContextHelper.CurrentObjectContext;
            var query = from c in context.Categories
                        orderby c.DisplayOrder
                        where (showHidden || c.Published) && 
                        !c.Deleted && 
                        c.ParentCategoryId == parentCategoryId
                        select c;
            var categories = query.ToList();
            return categories;
        }

[深海线]

我也知道有递归的分法啊，但是在ASP.NET 中的泛型集合，我不知道递归的写法。还请YXF 指教。

[深海线]

自己顶上去，高手帮忙，我的基础差。

[safinyxf]

只要你用递归，就可以实现N级菜单