2017-5-8 TreeView 实现三级联动 （递归方法）

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using 三级联动.App_code;

namespace treeview
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        List<chinastate> list = new chinastatedata().select();
        private void button1_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < 10;i++ )
            {
                //TreeNode tn = new TreeNode();
                //tn.Name =i.ToString();
                //tn.Text = i.ToString();
                //for (int j = 0; j < 10;j++ )
                //{
                //    TreeNode tn1 = new TreeNode();
                //    tn1.Name = j.ToString();
                //    tn1.Text = j.ToString();
                //    for (int k = 0; k < 10;k++ ) 
                //    {
                //        TreeNode tn2 = new TreeNode();
                //        tn2.Name = k.ToString();
                //        tn2.Text = k.ToString();
                //        tn1.Nodes.Add(tn2);
                //    }
                //   tn.Nodes.Add(tn1);
                //}

                //treeView1.Nodes.Add(tn);
                foreach(chinastate c in list)
                {
                    if(c.ParentAreaCode=="0001")
                    {
                        //省级
                    TreeNode tn = new TreeNode();
                    tn.Name = c.AreaCode;
                    tn.Text = c.AreaName;
                    bind(tn);
                        //foreach(chinastate cc in list)
                        //{
                        //    if(cc.ParentAreaCode==c.AreaCode)
                        //    {
                        //        TreeNode tn1=new TreeNode();
                        //        tn1.Name=cc.AreaCode;
                        //        tn1.Text=cc.AreaName;
                        //        tn.Nodes.Add(tn1);
                        //    }
                        //}
                    treeView1.Nodes.Add(tn);
                    }
                }
            }
        }

        //递归方法
        public void bind(TreeNode tn)
        {
            foreach (chinastate c in list)
            {
                if (c.ParentAreaCode == tn.Name)
                {
                    TreeNode tn1 = new TreeNode();
                    tn1.Text = c.AreaName;
                    tn1.Name = c.AreaCode;
                    bind(tn1);
                    tn.Nodes.Add(tn1);
                }
            }
        }
        private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            MessageBox.Show(treeView1.SelectedNode.Text+" | "+treeView1.SelectedNode.Name);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 三级联动.App_code
{
   public  class chinastate
    {
        private string _AreaCode;

        public string AreaCode
        {
            get { return _AreaCode; }
            set { _AreaCode = value; }
        }
        private string _AreaName;

        public string AreaName
        {
            get { return _AreaName; }
            set { _AreaName = value; }
        }
        private string _ParentAreaCode;

        public string ParentAreaCode
        {
            get { return _ParentAreaCode; }
            set { _ParentAreaCode = value; }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 三级联动.App_code
{
    public class chinastatedata
    { 
        SqlConnection conn=null;
        SqlCommand cmd=null;

        public chinastatedata()
     {
         conn = new SqlConnection("server=.;database=data0216;user=sa;pwd=123");
         cmd = conn.CreateCommand();
     }

        public List<chinastate> select(string pcode) 
        {
            List<chinastate> clist = new List<chinastate>();
            cmd.CommandText = "select * from ChinaStates where ParentAreaCode=@a";
            cmd.Parameters.Clear();
            cmd.Parameters.AddWithValue("@a",pcode);
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            while(dr.Read())
            {
                chinastate c = new chinastate();
                c.AreaCode = dr[0].ToString();
                c.AreaName = dr[1].ToString();
                c.ParentAreaCode = dr[2].ToString();
                clist.Add(c);
            }
            conn.Close();

            return clist;
        }

        public List<chinastate> select()
        {
            List<chinastate> clist = new List<chinastate>();
            cmd.CommandText = "select * from ChinaStates";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                chinastate c = new chinastate();
                c.AreaCode = dr[0].ToString();
                c.AreaName = dr[1].ToString();
                c.ParentAreaCode = dr[2].ToString();
                clist.Add(c);

            }
            conn.Close();

            return clist;
        }


    }
    
}