using System; 
using System.Configuration; 
using System.Data; 
using System.Linq; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.HtmlControls; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Data.SqlClient; 
 
public partial  class _Default : System.Web.UI.Page    
{ 
         protected  void Page_Load( object sender, EventArgs e) 
        { 
                 if (!IsPostBack) 
                { 
                         //填充第一级节点 
                        DataView dv = drv( "select * from big"); 
                         foreach (DataRowView datav  in dv) 
                        { //循环数据，读取到节点上 
                                TreeNode tn =  new TreeNode(); 
                                tn.Text = datav[ "title"].ToString(); 
                                tn.Value = datav[ "bid"].ToString(); 
                                tn.Expanded =  false;  //当前节点都是折叠起来的 
                                TreeView1.Nodes.Add(tn);  //填充 
                                AddchildNodes(tn);  //调用方法填充二级节点 
                        } 
                } 
        } 
         private DataView drv( string sql) 
        { 
                 string conn =  "Server=.;User id=sa;Pwd=L;Database=test";     //这个是我本地的数据库命令 
                SqlConnection con =  new SqlConnection(conn); 
                SqlDataAdapter sda =  new SqlDataAdapter(sql, con); 
                DataSet ds =  new DataSet(); 
                sda.Fill(ds,  "tree"); 
                 return ds.Tables[ "tree"].DefaultView;     //注意一下这里的返回值 
        } 
         private  void AddchildNodes(TreeNode tn) 
        { //二级节点 
                 int bid = Convert.ToInt32(tn.Value); 
                DataView dv = drv( "select * from class where bid = " + bid + ""); 
                 foreach (DataRowView datav  in dv) 
                { 
                        TreeNode ctn =  new TreeNode(); 
                        ctn.Text = datav[ "title"].ToString(); 
                        ctn.Value = datav[ "cid"].ToString(); 
                        ctn.NavigateUrl =  "http://mixangel.blog.51cto.com/"; 

                        tn.ChildNodes.Add(ctn);    //加载到tn的下级节点 

                } 

        } 

        protected void Button1_Click(object sender, EventArgs e) 

        { 

                //按钮事件，根据check选定与否来显示 

                if (TreeView1.CheckedNodes.Count > 0) 

                { 

                        foreach (TreeNode tn in TreeView1.CheckedNodes) 

                        { 

                                if (tn.ChildNodes.Count > 0) 

                                { 

                                        foreach (TreeNode ctn in tn.ChildNodes) 

                                        { 

                                                Response.Write(ctn.Text + "<br>"); 

                                        } 

                                } 

                                else 

                                { 

                                        Response.Write(tn.Text + "<br>"); 

                                } 

                        } 

                } 

        } 

 

        //下面是TreeView的三个事件，非常简单，就是点击TreeView触发的事件，代码实现后可以看看效果。 

        protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e) 

        { 

                Label1.Text = TreeView1.SelectedNode.Text; 

        } 

        protected void TreeView1_TreeNodeCollapsed(object sender, TreeNodeEventArgs e) 

        { 

                Label1.Text = "你折叠了" + e.Node.Text; 

        } 

        protected void TreeView1_TreeNodeExpanded(object sender, TreeNodeEventArgs e) 

        { 

                Label1.Text = "你展开了" + e.Node.Text; 

        } 

}