掌握TreeView用法

DAL层代码：

using System.Collections.Generic;
using System.Data;
using DataTreeModel;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace DataTreeDAL
{
    class TreesNodeDAL
    {
        //根据Parentid返回表中所有的的实体对象
        public IEnumerable<ItemsNode> GetEveryOneByParent(int id)
        { 
        DataTable dt=sqlHelper.GetDatatable("select * from ItemsNode where parentId =@id",
            new SqlParameter("id",id));
        List<ItemsNode> list = new List<ItemsNode>();
            foreach (DataRow row in dt.Rows)
            {
                list.Add(CreateItemsNose(row));//添加对象
            }
            return list;
        }
        //更新表中的记录
        public int UpdateRecord(ItemsNode item)
        {
         return sqlHelper.ExecuteNonQuery("update ItemsNode set name=@name,content=@content where id=@id", new SqlParameter("name", item.name), new SqlParameter("content", item.content),new
             SqlParameter("id",item.Id));
        }

        public int InsertRecord(ItemsNode item)
        {
            return sqlHelper.ExecuteNonQuery("Insert into ItemsNode (name,content,parentId) values(@name,@content,@parentId)", new SqlParameter("name", item.name), new SqlParameter("content", item.content), new
            SqlParameter("parentId", item.parentId));
        }

        public void DeleteNode(int ParentId)
        {
            //获得以该节点为父节点的所有子节点
            IEnumerable<ItemsNode> childens = GetEveryOneByParent(ParentId);
            foreach (ItemsNode child in childens)
            {
                DeleteNode((int)child.Id);
            }
           Delete(ParentId);
        }
      
        //实例化对象
        private static ItemsNode CreateItemsNose(DataRow row)
        {
            ItemsNode item = new ItemsNode();
            item.Id = row.IsNull("Id")?null:(int?)row["Id"];
            item.name = (string)row["name"];
            item.parentId = row.IsNull("parentId") ? null : (int?)row["parentId"];
            item.content = (string)row["content"];
            return item;
        }
        //删除操作
        public  int Delete(int id)
        {
            return sqlHelper.ExecuteNonQuery("delete from ItemsNode where id=@id",
            new SqlParameter("id", id));
        }
    }
}

BLL层代码：

using System;
using System.Collections.Generic;
using System.Text;
using DataTreeDAL;
using DataTreeModel;

namespace DataTreeBLL
{
    class TreeNodeBLL
    {
        //获得所有对象
        public IEnumerable<ItemsNode> GetEveryOneByParent(int id)
        {
            return new TreesNodeDAL().GetEveryOneByParent(id);
        }
        //更新
        public int UpdateRecord(ItemsNode item)
        {
            return new TreesNodeDAL().UpdateRecord( item);
        }

        //增加
        public int InsertRecord(ItemsNode item)
        {
            return new TreesNodeDAL().InsertRecord(item);
        }

        public void DeleteAllNode(int ParentId)
        {
            new TreesNodeDAL().DeleteNode(ParentId);
        }
    }
}

UI层代码：

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using DataTreeBLL;
using DataTreeModel;

namespace DataTree
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //获取所有的父节点对象
          IEnumerable<ItemsNode> items= new TreeNodeBLL().GetEveryOneByParent(0);
          
            foreach(ItemsNode item in items)
            {  
                //创建一个节点实例
                TreeNode Fnode = new TreeNode();
                Fnode.Text = item.name;
                Fnode.Tag = item;
                treeView1.Nodes.Add(Fnode);
                GetChildNode(Fnode,(int)item.Id); 
            }
            treeView1.ExpandAll();
        }
        //遍历子节点
        protected void GetChildNode(TreeNode Pnode,int id)
        {
            //获取所有以此节点最为的父节点对象
            IEnumerable<ItemsNode> items = new TreeNodeBLL().GetEveryOneByParent(id);
            foreach (ItemsNode item in items)
            {
                TreeNode Fnode = new TreeNode();
                Fnode.Text = item.name;
                Fnode.Tag = item;//把节点的Tag指向对象
                Pnode.Nodes.Add(Fnode);
                GetChildNode(Fnode, (int)item.Id);
            }
        }

        private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            ItemsNode item = (ItemsNode)e.Node.Tag;
            tb_content.Text = item.content;
        }

        private void bt_modify_Click(object sender, EventArgs e)
        {
            ItemsNode item = (ItemsNode)treeView1.SelectedNode.Tag;
            Frmodify form = new Frmodify();
            form.FName = item.name;
            form.Content = item.content;
            if (form.ShowDialog()== DialogResult.OK)//递交修改指令
            {
                item.name = form.FName;
                item.content = form.Content;
                new TreeNodeBLL().UpdateRecord(item);
                treeView1.SelectedNode.Text = item.name;
                tb_content.Text = item.content; 
            }
        }

        private void bt_Insert_1_Click(object sender, EventArgs e)
        {
            Frmodify form = new Frmodify();
            if (form.ShowDialog() == DialogResult.OK)
            {
                ItemsNode item = new ItemsNode();
                item.name=form.FName;
                item.content=form.Content;
                item.parentId = 0;//一级节点
                new TreeNodeBLL().InsertRecord(item);
                TreeNode Node = new TreeNode();
                Node.Text=item.name;
                Node.Tag=item;
                treeView1.Nodes.Add(Node);
            }
        }

        private void bt_Insert2_Click(object sender, EventArgs e)
        {
            TreeNode CurrentNode = treeView1.SelectedNode;
            Frmodify form = new Frmodify();
            if (form.ShowDialog() == DialogResult.OK)
            {
                ItemsNode item = (ItemsNode)CurrentNode.Tag;
                item.name = form.FName;
                item.content = form.Content;
                item.parentId=item.Id;
                new TreeNodeBLL().InsertRecord(item);
                //显示到界面
                TreeNode Node = new TreeNode();
                Node.Text = item.name;
                Node.Tag = item;
                CurrentNode.Nodes.Add(Node);
            }
        }

        private void bt_Delete_Click(object sender, EventArgs e)
        {
            TreeNode Node = treeView1.SelectedNode;
            Node.Remove();
            ItemsNode item = (ItemsNode)Node.Tag;
            new TreeNodeBLL().DeleteAllNode((int)item.Id);
        }
    }
}

SQLhelper 类

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DataTreeDAL
{
    class sqlHelper
    {
        protected static readonly string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
        //返回一个结果集
        public static DataTable GetDatatable(string sql,params SqlParameter[] Paramers)
        {
            using (SqlConnection con = new SqlConnection(conStr))//创建一个连接
            {
                con.Open();//打开连接通道
                using (SqlCommand cmd =con.CreateCommand())//创建一个命令对象
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(Paramers);
                    SqlDataAdapter da = new SqlDataAdapter(cmd);
                    DataTable dt = new DataTable();
                    da.Fill(dt);
                    return dt;
                }
            }
        }
       
        public static int ExecuteNonQuery(string sql, params SqlParameter[] Paramers)
        {
            using (SqlConnection con = new SqlConnection(conStr))//创建一个连接
            {
                con.Open();//打开连接通道
                using (SqlCommand cmd = con.CreateCommand())//创建一个命令对象
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(Paramers);
                    return cmd.ExecuteNonQuery();
                }
            }
        }
    }
}