后台代码:
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;
using System.Data.SqlClient;
public partial class control_TreeViewControl : System.Web.UI.UserControl
{
    private int opclass = 1;//默人权限最小为个人
    /// <summary>
    /// 修改opclass的属性
    /// </summary>
    public int Opclass
    {
        get { return opclass; }
        set { opclass = value; }
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        Opclass = Session["OptClass"].ToString();//从session中取得权限
        if (!IsPostBack)
        {
            TreeNode trObj = new TreeNode("首页", "00");
            trObj.NavigateUrl = "../Default.aspx";
            //trObj.Target = "main";
            trObj.PopulateOnDemand = true;//动态填充设置为true
            TreeViewlist.Nodes.Add(trObj);
        }
    }

    private void PopulateFirst(TreeNode node)
    {
        // Query for the product categories. These are the values
        // for the second-level nodes.
        DataSet ResultSet = RunQuery("Select ModuleName,ModuleID From fn_visit_table(" + opclass + ") Where len(ModuleID)=3 and ModuleId like '21_'");//加载一级菜单
        // Create the second-level nodes.
        if (ResultSet.Tables.Count > 0)
        {
            // Iterate through and create a new node for each row in the query results.
            // Notice that the query results are stored in the table of the DataSet.
            foreach (DataRow row in ResultSet.Tables[0].Rows)
            {
                // Create the new node. Notice that the CategoryId is stored in the Value property
                // of the node. This will make querying for items in a specific category easier when
                // the third-level nodes are created.
                TreeNode newNode = new TreeNode();
                newNode.Text = row["ModuleName"].ToString();
                newNode.Value = row["ModuleID"].ToString();
                // Set the PopulateOnDemand property to true so that the child nodes can be
                // dynamically populated.
                newNode.PopulateOnDemand = true;
                // Set additional properties for the node.
                newNode.SelectAction = TreeNodeSelectAction.Expand;
                // Add the new node to the ChildNodes collection of the parent node.
                node.ChildNodes.Add(newNode);
            }
        }
    }
    private void PopulateSecond(TreeNode node)
    {
        // Query for the products of the current category. These are the values
        // for the third-level nodes.
        DataSet ResultSet = RunQuery("Select ModuleName,ModuleID,Remark From fn_visit_table(" + opclass + ")" +
            " Where len(ModuleID)=5 and substring(convert(char(8),ModuleID),1,3)='" + node.Value + "'");//加载二级菜单
        // Create the third-level nodes.
        if (ResultSet.Tables.Count > 0)
        {
            // Iterate through and create a new node for each row in the query results.
            // Notice that the query results are stored in the table of the DataSet.
            foreach (DataRow row in ResultSet.Tables[0].Rows)
            {
                // Create the new node.
                TreeNode newNode = new TreeNode();
                newNode.Text = row["ModuleName"].ToString();
                newNode.Value = row["ModuleID"].ToString();
                newNode.NavigateUrl = row["Remark"].ToString();
                // Set the PopulateOnDemand property to false, because these are leaf nodes and
                // do not need to be populated.
                newNode.PopulateOnDemand = true;
                // Set additional properties for the node.
                newNode.SelectAction = TreeNodeSelectAction.Expand;
                // Add the new node to the ChildNodes collection of the parent node.
                node.ChildNodes.Add(newNode);
            }
        }
    }

    private void PopulateThird(TreeNode node)
    {
        // Query for the products of the current category. These are the values
        // for the third-level nodes.
        DataSet ResultSet = RunQuery("Select ModuleName,ModuleID,Remark From fn_visit_table(" + opclass + ")" +
            " Where len(ModuleID)=8 and substring(convert(char(8),ModuleID),1,5)='" + node.Value + "'");////加载三级菜单
        // Create the third-level nodes.
        if (ResultSet.Tables.Count > 0)
        {
            // Iterate through and create a new node for each row in the query results.
            // Notice that the query results are stored in the table of the DataSet.
            foreach (DataRow row in ResultSet.Tables[0].Rows)
            {
                // Create the new node.
                TreeNode newNode = new TreeNode();
                newNode.Text = row["ModuleName"].ToString();
                newNode.Value = row["ModuleID"].ToString();
                newNode.NavigateUrl = row["Remark"].ToString();
                // Set the PopulateOnDemand property to false, because these are leaf nodes and
                // do not need to be populated.
                newNode.PopulateOnDemand = false;
                // Set additional properties for the node.
                newNode.SelectAction = TreeNodeSelectAction.Expand;//
                // Add the new node to the ChildNodes collection of the parent node.
                node.ChildNodes.Add(newNode);
            }
        }
    }
    private DataSet RunQuery(String QueryString)
    {
        String ConnectionString = ConfigurationManager.ConnectionStrings["MISDBConnectionString"].ToString();
        SqlConnection DBConnection = new SqlConnection(ConnectionString);
        SqlDataAdapter DBAdapter;
        DataSet ResultsDataSet = new DataSet();
        try
        {
            //运行查询和创建DataSet
            DBAdapter = new SqlDataAdapter(QueryString, DBConnection);
            DBAdapter.Fill(ResultsDataSet);
            DBConnection.Close();//关闭连接
        }
        catch
        {
            // 异常处理如果连接没有关闭，则关闭连接.
            if (DBConnection.State == ConnectionState.Open)
            {
                DBConnection.Close();
            }
            throw new Exception();
        }
        return ResultsDataSet;
    }
    protected void tvClass_TreeNodePopulate(object sender, TreeNodeEventArgs e)
    {
        // Call the appropriate method to populate a node at a particular level.
        int myTemp = e.Node.Depth;
        switch (myTemp)
        {
            case 0:
                // 装载第一层节点
                PopulateFirst(e.Node);
                break;
            case 1:
                // 装载第二层节点
                PopulateSecond(e.Node);//PopulateSecond
                break;
            case 2:
                // 装载第三层节点
                PopulateThird(e.Node);
                break;
            default:
                // Do nothing.
                break;
        }
    }
}
前台代码:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="TreeViewControl.ascx.cs" Inherits="control_TreeViewControl" %>
<asp:TreeView ID="TreeViewlist" runat="server" OnTreeNodePopulate="tvClass_TreeNodePopulate" CssClass="menutextindent" SkinID="TreeView">
</asp:TreeView>
效果图: