droplist下拉层级选择

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 1  public partial class WebForm1 : System.Web.UI.Page
 2     {
 3         protected void Page_Load(object sender, EventArgs e)
 4         {
 5             if (!IsPostBack)
 6             {
 7                 BindDrpClass();
 8             }
 9         }
10         private void BindDrpClass()
11         {
12             //获得所有数据列表
13             Maticsoft.BLL.L_Men sm = new Maticsoft.BLL.L_Men();
14             DataSet ds;
15             ds = sm.GetList("");
16             DataTable dt = ds.Tables[0];
17             ddl.Items.Clear();
18             ddl.Items.Add(new ListItem("选择类别", "0"));
19             DataRow[] drs = dt.Select("MenParentID= " + 0);//得到父ID
20 
21             foreach (DataRow dr in drs)
22             {
23                 string classid = dr["MenID"].ToString();
24                 string classname = dr["MenName"].ToString();
25                 //顶级分类显示形式
26                 classname = "" + classname;
27 
28                 ddl.Items.Add(new ListItem(classname, classid));
29                 int sonparentid = int.Parse(classid);
30                 string blank = "　|---";
31                 //递归子分类方法
32                 BindNode(sonparentid, dt, blank);
33             }
34             ddl.DataBind();
35         }
36         private void BindNode(int parentid, DataTable dt, string blank)
37         {
38             DataRow[] drs = dt.Select("MenParentID= " + parentid);
39 
40             foreach (DataRow dr in drs)
41             {
42                 string classid = dr["MenID"].ToString();
43                 string classname = dr["MenName"].ToString();
44 
45                 classname = blank + classname;
46                 ddl.Items.Add(new ListItem(classname, classid));
47 
48                 int sonparentid = int.Parse(classid);
49                 string blank2 = blank + "-";
50                 BindNode(sonparentid, dt, blank2);
51             }
52         }
53 
54         protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
55         {
56             Response.Write("选择值是:"+ddl.SelectedValue);
57         }
58 
59         protected void Button1_Click(object sender, EventArgs e)
60         {
61 
62         }
63       
64     }