DropDownList无限级分类(灵活控制显示形式)

来源：互联网发布：炉石代练软件编辑：程序博客网时间：2024/06/05 23:52

前台,aspx页面，只需要一个dropdownlist,textbox,button控件

数据库我选用的是access数据库，字段设置如图：

连接数据库省略自己写吧

后台页面代码aspx.cs（不能再仔细了）：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Default2 : System.Web.UI.Page
{
    cx c = new cx();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            BindDropdownList();//页面加载
        }

    }
    protected void BindDropdownList()//绑定dropdownlist实现商品类型无限级分类
    {
        DataTable dt = new DataTable();
        try
        {
            string sql = "select * from TB_Class1";
            dt = c.getdataSet(sql, "s").Tables[0];
            CreateLevelDropDown(this.DropDownList1, dt);
        }
        catch (Exception) { }

    }
    /// <summary>
    /// 创建分级下拉框
    /// </summary>
    /// <param name="ddlst"></param>
    /// <param name="dt"></param>
    private void CreateLevelDropDown(DropDownList ddlst, DataTable dt)
    {
        System.Collections.ArrayList allItems = new ArrayList();
        DataRow[] rows = dt.Select("[parent_id]=" + 0);
        foreach (DataRow row in rows)
            CreateLevelDropDownAssistant(dt, ref   allItems, row, string.Empty);

        ListItem[] items = new ListItem[allItems.Count];
        allItems.CopyTo(items);
        ddlst.Items.AddRange(items);
    }
    private void CreateLevelDropDownAssistant(DataTable dt, ref   ArrayList items, DataRow parentRow, string curHeader)
    {
        ListItem newItem = new ListItem(curHeader + parentRow["class_name"].ToString(), parentRow["class_id"].ToString());
        items.Add(newItem);
        parentRow.Delete();

        DataRow[] rows = dt.Select("[parent_id]='" + newItem.Value + "'");
        for (int i = 0; i < rows.Length - 1; i++)
            CreateLevelDropDownAssistant(dt, ref   items, rows[i], curHeader.Replace("┣", "┃").Replace("┗", "┣") + "┣");

        if (rows.Length > 0)
            CreateLevelDropDownAssistant(dt, ref   items, rows[rows.Length - 1], curHeader.Replace("┣", "┃").Replace("┗", "┣") + "┗");
    }

    protected void Button1_Click(object sender, EventArgs e)//添加分类
    {
        int id = Convert.ToInt32(this.DropDownList1.SelectedValue);
        string sql = "";

        if (id == 1)//表示是根目录
        {
            sql = "insert into TB_Class1 (parent_id,class_name) values ('" + id + "','" + this.TextBox1.Text + "')";
            c.ExeSql(sql);
            Response.Write("<script>alert('跟栏目添加成功！')</script>");
        }
        else//在根栏目下添加子栏目
        {
            sql = "insert into TB_Class1 (parent_id,class_name) values ('" + id + "','" + this.TextBox1.Text + "')";
            c.ExeSql(sql);
            Response.Write("<script>alert('子栏目添加成功！')</script>");
        }
        this.DropDownList1.Items.Clear();//清空dropdownlist
        BindDropdownList();//重新加载，添加数据完全显示

    }

}
显示效果，如图：

显示另一效果：

这种效果前台显示一样，数据库设计如下：

后台代码如下：

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
using System.Data.OleDb;

public partial class _Default : System.Web.UI.Page
{
    cx c = new cx();
    protected void Page_Load(object sender, EventArgs e)
    {
        if(!Page.IsPostBack)
        {
            BindDrpClass();
        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        int id = Convert.ToInt32(this.DropDownList1.SelectedValue);
        string sql = "";

        if (id == 0)//表示是根目录
        {
            sql = "insert into TB_Class2 (parent_id,class_name) values ('" + id + "','" + this.TextBox1.Text + "')";
            c.ExeSql(sql);
            Response.Write("<script>alert('跟栏目添加成功！')</script>");
        }
        else//在根栏目下添加子栏目
        {
            sql = "insert into TB_Class2 (parent_id,class_name) values ('" + id + "','" + this.TextBox1.Text + "')";
            c.ExeSql(sql);
            Response.Write("<script>alert('子栏目添加成功！')</script>");
        }
        this.DropDownList1.Items.Clear();//清空dropdownlist
        BindDrpClass();//重新加载，添加数据完全显示
    }
    private void BindDrpClass()
    {

        string sql = "select * from TB_Class2";
        DataTable dt = c.getdataSet(sql, "s").Tables[0];
        this.DropDownList1.Items.Add(new ListItem("添加根栏目", "0"));

DataRow[] drs = dt.Select("parent_id= " + 0);

     foreach (DataRow dr in drs)
     {
     string classid = dr["class_id"].ToString();
     string classname = dr["class_name"].ToString();
     //顶级分类显示形式
     classname = "╋" + classname;

     this.DropDownList1.Items.Add(new ListItem(classname, classid));
    int sonparentid = int.Parse(classid);
     string blank = "├";
     //递归子分类方法
     BindNode(sonparentid, dt, blank);
     }
     this.DropDownList1.DataBind();
     }
     //绑定子分类
     private void BindNode(int parentid, DataTable dt, string blank)
     {
         DataRow[] drs = dt.Select("parent_id= " + parentid);

         foreach (DataRow dr in drs)
         {
         string classid = dr["class_id"].ToString();
         string classname = dr["class_name"].ToString();

classname = blank + classname;
this.DropDownList1.Items.Add(new ListItem(classname, classid));

int sonparentid = int.Parse(classid);
string blank2 = blank + "─";

         BindNode(sonparentid, dt, blank2);
         }
     }

}
其实这两种方法相同，显示效果不一样而已，大家尽情交流！！！