【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：

代码

1  <% @ 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：

代码

 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：

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

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

  

显示效果：