主要使用递归实现，数据库结构：

最终样式：

 1

protected

 

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：

 

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>) 

/// 
        /// 创建树        /// 
        public void BindDrpClass(Guid selectId)        {            var list = repo.GetXzqyRootsList();            List
     
       selitem = new List
      
       ();            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
       
         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);            }        }