动态生成树结构TreeView控件的使用(源码)

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 Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
if(e.Node.ChildNodes.Count==0)
{
switch(e.Node.Depth)
{
case 0:
PopulateCategories(e.Node);
break;
case 1:
PopulateProducts(e.Node);
break;
}
}
}
public void PopulateCategories(TreeNode node)
{
SqlCommand sqlQuery = new SqlCommand("select categoryname,categoryid from categories");
DataSet resultset;
resultset = RunQuery(sqlQuery);
if(resultset.Tables.Count>0)
{
foreach(DataRow row in resultset.Tables[0].Rows)
{
TreeNode NewNode = new TreeNode(row["Categoryname"].ToString(),row["categoryid"].ToString());
NewNode.PopulateOnDemand = true;
NewNode.SelectAction = TreeNodeSelectAction.Expand;
node.ChildNodes.Add(NewNode);
}
}
}
public void PopulateProducts(TreeNode node)
{
SqlCommand sqlQuery = new SqlCommand();
sqlQuery.CommandText = "select productname from products"+" where categoryid=@categoryid";
sqlQuery.Parameters.Add("@categoryid",SqlDbType.Int).Value=node.Value;
DataSet ResultSet = RunQuery(sqlQuery);
if(ResultSet.Tables.Count>0)
{
foreach(DataRow row in ResultSet.Tables[0].Rows)
{
TreeNode NewNode = new TreeNode(row["productname"].ToString());
NewNode.PopulateOnDemand = false;
NewNode.SelectAction = TreeNodeSelectAction.None;
node.ChildNodes.Add(NewNode);
}
}
}
public DataSet RunQuery(SqlCommand sqlQuery)
{
string con_str = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
SqlConnection con=new SqlConnection(con_str);
SqlDataAdapter dbadapter=new SqlDataAdapter();
dbadapter.SelectCommand=sqlQuery;
sqlQuery.Connection=con;
DataSet resultdataset=new DataSet();
try
{
dbadapter.Fill(resultdataset);
}
catch
{
Label1.Text="无数据";
}
return resultdataset;
}
}