转载笔记：DropDownList无限级分类(灵活控制显示形式)

主要使用递归实现，数据库结构：

最终样式：

 1protected void Page_Load(object sender, EventArgs e)
 2    {
 3        if (!Page.IsPostBack)
 4        {
 5            BindDrpClass();
 6        }
 7    }
 8    //绑定顶级分类
 9    private void BindDrpClass()
10    {
11        Bll.Class classSystem = new Bll.Class();
12        DataTable dt = classSystem.GetClassList("").Tables[0];
13        ddlClass.Items.Clear();
14        ddlClass.Items.Add(new ListItem("添加根栏目","0"));
15        DataRow[] drs = dt.Select("ParentID= " + 0);
16
17        foreach (DataRow dr in drs)
18        {
19            string classid = dr["ClassID"].ToString();
20            string classname = dr["ClassName"].ToString();
21            //顶级分类显示形式
22            classname = "╋" + classname;
23
24            ddlClass.Items.Add(new ListItem(classname, classid));
25            int sonparentid = int.Parse(classid);
26            string blank = "├";
27            //递归子分类方法
28            BindNode(sonparentid, dt, blank);
29        }
30        ddlClass.DataBind();
31    }
32    //绑定子分类
33    private void BindNode(int parentid, DataTable dt, string blank)
34    {
35        DataRow[] drs = dt.Select("ParentID= " + parentid);
36
37        foreach (DataRow dr in drs)
38        {
39            string classid = dr["ClassID"].ToString();
40            string classname = dr["ClassName"].ToString();
41
42            classname = blank + classname;
43            ddlClass.Items.Add(new ListItem(classname, classid));
44
45            int sonparentid = int.Parse(classid);
46            string blank2 = blank + "─";
47
48            BindNode(sonparentid, dt, blank2);
49        }
50    }

源码下载：

https://files.cnblogs.com/chensubo/RecursionDemo.rar

改造过的函数 

// <asp:DropDownList ID="editparentid"  runat="server" ></asp:DropDownList>

   /// <summary>
    ///  加载页面 
    ///</summary>
    protected void Page_Load(object sender, EventArgs e)
    {

       BindDrpClass(editparentid);}

/// <summary>

/// 创建树
    /// </summary>
    public void BindDrpClass(DropDownList ddlClass)
    {
        DataTable dt = DbHelper.ExecuteDataset(SysConst.DBNAME_XIAOWU, "select * from NT_Clcs_ClientType").Tables[0];
        ddlClass.Items.Clear();
        ddlClass.Items.Add(new ListItem("添加根栏目", "0"));
        DataRow[] drs = dt.Select("ParentID= " + 0);
        foreach (DataRow dr in drs){
            string classid = dr["Cc_ID"].ToString();
            string classname = dr["Cc_Name"].ToString();
            //顶级分类显示形式
            classname = "╋" + classname;

            ddlClass.Items.Add(new ListItem(classname, classid));
            int sonparentid = int.Parse(classid);
            string blank = "├";
            //递归子分类方法
            BindNode(ddlClass, sonparentid, dt, blank);
        }
        editparentid.DataBind();
    }
    /// <summary>
    /// 创建树结点
    /// </summary>
    private void BindNode(DropDownList ddlNode, int parentid, DataTable dt, string blank)
    { 
        DataRow[] drs = dt.Select("ParentID= " + parentid);
        foreach (DataRow dr in drs){
            string classid = dr["Cc_ID"].ToString();
            string classname = dr["Cc_Name"].ToString();
            classname = blank + classname;
            ddlNode.Items.Add(new ListItem(classname, classid));
            int sonparentid = int.Parse(classid);
            string blank2 = blank + "─";
            BindNode(ddlNode,sonparentid, dt, blank2);
        }
    }

 

二次改造做成一个通用的类 调用  如：  new DrpGradingList("select * from dbo.NT_Clcs_ClientType ", "Cc_Name", "Cc_ID", defValue).BindDrpClass(ddl);

    /// <summary>
    /// DropDownList 树形显示
    /// </summary>
    public class DrpGradingList
    {
        private string Sql = "";
        private string Text = "";
        private string Value = "";
        private string defValue = "";
        private string parentId = "ParentID";
        /// <summary>
        ///  DropDownList 树形显示
        /// </summary>
        /// <param name="sql">SQL语句</param>
        /// <param name="text">显示的文本（ 数据库字段）</param>
        /// <param name="value">显示的文本对应的值（ 数据库字段）</param>
        public DrpGradingList(string sql, string text, string value, string defvalue)
        {
            this.Sql = sql;
            this.Text = text;
            this.Value = value;
            this.defValue = defvalue;
        }
        /// <summary>
        ///  DropDownList 树形显示
        /// </summary>
        /// <param name="sql">SQL语句</param>
        /// <param name="text">显示的文本（ 数据库字段）</param>
        /// <param name="value">显示的文本对应的值（ 数据库字段）</param>
        public DrpGradingList(string sql, string text, string value, string defvalue,string pid)
        {
            this.Sql = sql;
            this.Text = text;
            this.Value = value;
            this.defValue = defvalue;
            this.parentId = pid;
        }
        /// <summary>
        /// 创建树
        /// </summary>
        public void BindDrpClass(DropDownList ddlClass)
        {
            DataTable dt = DbHelper.ExecuteDataset(SysConst.DBNAME_XIAOWU, Sql).Tables[0];
            ddlClass.Items.Clear();
            ddlClass.Items.Add(new ListItem("顶级栏目", "0"));
            DataRow[] drs = dt.Select(""+this.parentId+"= " + 0);
            foreach (DataRow dr in drs)
            {
                string classid = dr[this.Value].ToString();
                string classname = dr[this.Text].ToString();
                //顶级分类显示形式
                classname = "╋" + classname;

                ListItem itme = new ListItem();
                itme.Text=classname;
                itme.Value=classid;
                if (itme.Value.Equals(this.defValue))
                    itme.Selected = true;

                ddlClass.Items.Add(itme);
                int sonparentid = int.Parse(classid);
                string blank = "├";
                //递归子分类方法
                BindNode(ddlClass, sonparentid, dt, blank);
            }
            ddlClass.SelectedIndex = ddlClass.Items.IndexOf(ddlClass.Items.FindByValue(this.defValue));
            ddlClass.DataBind();
        }
        /// <summary>
        /// 创建树  ddlClass.Items.Add(new ListItem("顶级栏目", "0"));
        /// </summary>
        public void BindDrpClass(DropDownList ddlClass, bool defItem)
        {
            DataTable dt = DbHelper.ExecuteDataset(SysConst.DBNAME_XIAOWU, Sql).Tables[0];
            ddlClass.Items.Clear();
            if (defItem){
                ddlClass.Items.Add(new ListItem("顶级栏目", "0"));
            }
            DataRow[] drs = dt.Select("" + this.parentId + "= " + 0);
            foreach (DataRow dr in drs)
            {
                string classid = dr[this.Value].ToString();
                string classname = dr[this.Text].ToString();
                //顶级分类显示形式
                classname = "╋" + classname;

                ListItem itme = new ListItem();
                itme.Text = classname;
                itme.Value = classid;
                if (itme.Value.Equals(this.defValue))
                    itme.Selected = true;

                ddlClass.Items.Add(itme);
                int sonparentid = int.Parse(classid);
                string blank = "├";
                //递归子分类方法
                BindNode(ddlClass, sonparentid, dt, blank);
            }
            ddlClass.SelectedIndex = ddlClass.Items.IndexOf(ddlClass.Items.FindByValue(this.defValue));
            ddlClass.DataBind();
        }
        public void BindDrpClass(DropDownList ddlClass, bool defItem,string parentIdefVale)
        {
            if (parentIdefVale.Length == 0) parentIdefVale = "0";
            DataTable dt = DbHelper.ExecuteDataset(SysConst.DBNAME_XIAOWU, Sql).Tables[0];
            ddlClass.Items.Clear();
            if (defItem)
            {
                ddlClass.Items.Add(new ListItem("顶级栏目", "0"));
            }
            DataRow[] drs = dt.Select("" + this.parentId + "= " + parentIdefVale);
            foreach (DataRow dr in drs)
            {
                string classid = dr[this.Value].ToString();
                string classname = dr[this.Text].ToString();
                //顶级分类显示形式
                classname = "╋" + classname;

                ListItem itme = new ListItem();
                itme.Text = classname;
                itme.Value = classid;
                if (itme.Value.Equals(this.defValue))
                    itme.Selected = true;

                ddlClass.Items.Add(itme);
                int sonparentid = int.Parse(classid);
                string blank = "├";
                //递归子分类方法
                BindNode(ddlClass, sonparentid, dt, blank);
            }
            ddlClass.SelectedIndex = ddlClass.Items.IndexOf(ddlClass.Items.FindByValue(this.defValue));
            ddlClass.DataBind();
        }
        /// <summary>
        /// 创建树结点
        /// </summary>
        private void BindNode(DropDownList ddlNode, int parentid, DataTable dt, string blank)
        {
            DataRow[] drs = dt.Select(""+this.parentId+"= " + parentid);
            foreach (DataRow dr in drs)
            {
                string classid = dr[this.Value].ToString();
                string classname = dr[this.Text].ToString();
                classname = blank + classname;

                ListItem itme = new ListItem();
                itme.Text = classname;
                itme.Value = classid;
                if (itme.Value.Equals(this.defValue))
                    itme.Selected = true;
                ddlNode.Items.Add(itme);

                int sonparentid = int.Parse(classid);
                string blank2 = blank + "─";
                BindNode(ddlNode, sonparentid, dt, blank2);
            }
        }
    }

 RadTreeView控件 应用：

 

<telerik:RadTreeView runat="server" ID="RadTreeView2" Skin="Office2007"
             Width="300px" Height="450px" CheckBoxes="True" DataTextField="ParentID" 
                TriStateCheckBoxes="False">
            </telerik:RadTreeView>  

 AddTree("0", this.RadTreeView2.Nodes);

 public void AddTree(string fdm, RadTreeNodeCollection nodes)
    {
        DataTable dt = DbHelper.ExecuteDataset(SysConst.DBNAME_XIAOWU, "select * from NT_Clcs_Village where ParentID=" + fdm + "").Tables[0];

        foreach (DataRow dr in dt.Rows)
        {
            string classid = dr["Cv_ID"].ToString();
            string classname = dr["Cv_Name"].ToString();

            RadTreeNode main = new RadTreeNode();
            main.Text = classname;
            main.Value = classid;
            nodes.Add(main);
            AddTree(classid, main.Nodes);
        }

   } 

 其它：

dropDownList.SelectedIndex=dropDownList.Items.IndexOf(dropDownList.Items.FindByText(entityBase.Bugstatus));

 MVC树形：

使用： @Html.DropDownList("ddlXzqy", ViewData["ddlXzqy"] as IEnumerable<SelectListItem>) 

 /// <summary>
        /// 创建树
        /// </summary>
        public void BindDrpClass(Guid selectId)
        {
            var list = repo.GetXzqyRootsList();
            List<SelectListItem> selitem = new List<SelectListItem>();
            foreach (var item in list)
            {
                //顶级分类显示形式
                if (selectId == item.ID)
                {
                    selitem.Add(new SelectListItem { Text = "╋" + item.Name, Value = item.ID.ToString(), Selected = true });
                    this.ViewData["selected"] = item.ID.ToString();
                }
                else
                {
                    selitem.Add(new SelectListItem { Text = "╋" + item.Name, Value = item.ID.ToString() });
                }

                //递归子分类方法
                string blank = "├";
                BindNode(item.ID, blank, selitem, selectId);
            }
            selitem.Insert(0, new SelectListItem { Text = "==行政区域==", Value = "-1" });
            ViewData["ddlXzqy"] = selitem;
        }
        private void BindNode(Guid parentid, string blank, List<SelectListItem> selitem, Guid selectId)
        {
            var list = repo.GetXzqyChildList(parentid);
            foreach (var item in list)
            {
                if (selectId == item.ID)
                {
                    selitem.Add(new SelectListItem { Text = blank + item.Name, Value = item.ID.ToString(), Selected = true });
                    this.ViewData["selected"] = item.ID.ToString();
                }
                else
                {
                    selitem.Add(new SelectListItem { Text = blank + item.Name, Value = item.ID.ToString() });
                }
                string blank2 = blank + "─";
                BindNode(item.ID, blank2, selitem, selectId);
            }
        }