.net 无限级分类

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.Text;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 
{

    System.Text.StringBuilder sb = new StringBuilder();
    //默认深度1；
    public int i = 1;

    protected void Page_Load(object sender, EventArgs e)
    {
        if(!this.IsPostBack)
        {
            this.buildTree();
        }
    }

    /// <summary>
    /// 创建树
    /// </summary>
    private void buildTree()
    {

        DataSet ds = ExecuteDataSet("select * from Sort");

        //建立关系
        ds.Relations.Add("SortRelation", ds.Tables[0].Columns["SortId"], ds.Tables[0].Columns["ParentSortId"]);

        //遍历每行并根据数据行关系生成树
        foreach (DataRow dbRow in ds.Tables[0].Rows)
        {
            if (dbRow.IsNull("ParentSortId"))
            {
                string s = CreateNode(dbRow["SortName"].ToString());
                sb.Append(s);
                PopulateSubTree(dbRow,i);
                
            }
        }
        
        this.Response.Write(sb);
    }

   /// <summary>
   /// 遍历子类
   /// </summary>
   /// <param name="dbRow">遍历的Row</param>
   /// <param name="depth">深度（用于显示空格个数）</param>
    private void PopulateSubTree(DataRow dbRow,int depth)
    {
        ++depth;
        foreach (DataRow childRow in dbRow.GetChildRows("SortRelation"))
        {
            string s = "";
            for (int j=1;j<=depth;j++ )
            {
                s = "&nbsp" + s;
            }
            s += "|-" + childRow["SortName"].ToString() + "<br>";
           sb.Append(s);
           PopulateSubTree(childRow,depth);
        }
    }

    /// <summary>
    /// 显示父类名称
    /// </summary>
    /// <param name="sortname">类别名称</param>
    /// <returns></returns>
    private string CreateNode(string sortname)
    {
        string s = "|-"+sortname+"<br>";

        return s;
     }

     #region  返回dataset对象
     /// <summary>
     /// 返回dataset对象
     /// </summary>
     /// <param name="sql">sql语句</param>
     /// <returns></returns>
     public DataSet ExecuteDataSet(string sql)
     {
         SqlConnection con = new SqlConnection("server=.;database=sort;uid=sa;pwd=;");
         DataSet ds = new DataSet();
         SqlDataAdapter sda = new SqlDataAdapter(sql, con);
         sda.Fill(ds);
         return ds;
     }
     #endregion

}