【原】Dropdownlist多级实现

要求：实现dropdownlist的下拉框中包含所有分类。

数据库如下：

 

 

代码如下：（这里做成用户控件）

ascx文件：

 <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="UC_ddlCategroy.ascx.cs" Inherits="CartDemo.WebUI.UserControl.UC_ddlCategroy" %>
2 
3 <asp:DropDownList ID="ddlCategory" runat="server" BackColor="White" Font-Bold="True" ForeColor="Green" AutoPostBack="true">
4 </asp:DropDownList>

 

cs文件：

 1 public partial class UC_ddlCategroy : System.Web.UI.UserControl
 2     {
 3         /// <summary>
 4         /// 初始化
 5         /// </summary>
 6         /// <param name="sender"></param>
 7         /// <param name="e"></param>
 8         protected void Page_Load(object sender, EventArgs e)
 9         {
10             if (!IsPostBack)
11             {
12                 DataTable datatable = this.GetDataTable();
13                 if (datatable.Rows.Count > 0)
14                 {
15                     this.ddlCategory.Items.Add("全部分类");
16                     foreach (DataRow row in datatable.Rows)
17                     {
18                         if (row["CategoryPid"].ToString().Trim() == "0")
19                         {
20                             this.ddlCategory.Items.Add(new ListItem(row["CategoryName"].ToString(), row["CategoryId"].ToString()));
21                             addSonCategory(string.Empty, Convert.ToInt32(row["CategoryId"]), datatable, 1);
22                         }
23                     }
24                 }
25             }
26         }
27 
28         /// <summary>
29         /// 添加子节点
30         /// </summary>
31         /// <param name="strPading">空格</param>
32         /// <param name="DirId">父路径ID</param>
33         /// <param name="datatable">返回的datatable</param>
34         /// <param name="deep">树形的深度</param>
35         private void addSonCategory(string strPading, int id, DataTable datatable, int deep)
36         {
37             DataRow[] rowlist = datatable.Select("CategoryPid='" + id + "'");
38             foreach (DataRow row in rowlist)
39             {
40                 strPading = string.Empty;
41                 for (int j = 0; j < deep; j++)
42                 {
43                     strPading += "　";         //用全角的空格（智能abc输入法状态下的v11字符）
44                 }
45                 // 添加节点
46                 ListItem li = new ListItem(strPading + "|--" + row["CategoryName"].ToString());
47                 this.ddlCategory.Items.Add(li);
48                 // 递归调用addSonCategory函数，在函数中把deep加1
49                 addSonCategory(strPading, Convert.ToInt32(row["CategoryId"]), datatable, deep + 1);
50             }
51         }
52 
53         /// <summary>
54         /// 从数据库中读取数据返回datatable
55         /// </summary>
56         /// <returns></returns>
57         private DataTable GetDataTable()
58         {
59             SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString);
60             SqlDataAdapter adp = new SqlDataAdapter("SELECT * FROM [T_Category]", conn);
61             DataSet datset = new DataSet();
62             conn.Open();
63             adp.Fill(datset, "T_Category");
64             return datset.Tables[0];
65         }
66 
67         /// <summary>
68         /// SelectedValue属性（暴露给外部使用）
69         /// 只有Get方法，没有Set方法，保证只读
70         /// </summary>
71         public string SelectedValue
72         {
73             get 
74             {
75                 string strSelectedValue = this.ddlCategory.SelectedValue;
76 
77                 if (strSelectedValue.Contains("　") && (strSelectedValue.Contains("|--")))
78                 { // 如果是子类别
79                     int iStartIndex = strSelectedValue.LastIndexOf("|--") + 3;               // 字符串截取的起始位置
80                     strSelectedValue = strSelectedValue.Substring(iStartIndex);
81                 }
82 
83                 return strSelectedValue; 
84             }
85         }
86     }

 

别的aspx页面调用之：

 <%@ Register Src="~/UserControl/UC_ddlCategroy.ascx" TagName="ddlCategory" TagPrefix="uc1" %>

 <uc1:ddlCategory ID="ddlCategory" runat="server"  />

  

显示效果：