(转)ASP.NET 2.0 从数据库中读取数据生成分层的结构化TreeView

PS: 正在找一些分级显示的东西,后来决定用treeview做,事实上也不知道用其他方法如何实现该功能.当然,目的是为了达到文章分级显示,并对级别进行CUID操作,网上找了很久最终找到了这个.起码是可以实现的,不过似乎还是用到了递归,如果以后有好的会继续更新.

本文中的treeview控件id为trvMain,其他地方一般能看懂,不做过多说明

转自:http://hi.baidu.com/51zt/blog/item/d8bffe19c28a527adbb4bde5.html

原文如下:

这几天帮朋友研究一个电子商务网站,遇到一个物品分类的问题,就是想用TREEVIEW控件来做一个无限分级的分类树,现在终于解决了.

解决方法是这样的,查看TreeView控件的属性,会发现其中有一项是"PopulatNodesFromClient"

意思为:是否尝试从客户端填充节点.

那么看到了解释之后,当然是选择值为:"True".
在给"PopulatNodesFromClient"赋值为"True"之后,在TreeView的属性事件中就有一项为TreeNodePopulate事件,为:正在填充TreeNode时激发某事件,那么在给该事件写方法时,就可以写从数据库中读取相应的子节点内容了.
所以,每当TreeNode增加一个节点时,便激发该事件,以填充其子节点.

可生成一个空方法如下:
protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
//
}

下面举个完整的例子(连接数据库的类就不写了,只写了 Default.aspx 内的代码):

效果参考下图:




代码如下:


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.Data.OleDb;public partial class _Default : System.Web.UI.Page




...{


protected void Page_Load(object sender, EventArgs e)




...{


if (!Page.IsPostBack)




...{


InitRoot(trvMain);


}




}




/**//// <summary>


/// 通过SQL语句参数生成需要的DS


/// </summary>


/// <param name="sqlstr">SQL语句</param>


/// <returns></returns>


private DataSet CreateDataSet(string sqlstr)




...{


try




...{


clsConn myConn = new clsConn();


myConn.Open();


OleDbDataAdapter cd = new OleDbDataAdapter();


cd.SelectCommand = new OleDbCommand(sqlstr, myConn.ChangeType());


cd.SelectCommand.CommandType = CommandType.Text;




DataSet dsTree = new DataSet();


cd.Fill(dsTree, "Table");


myConn.Close();


return dsTree;


}


catch




...{


Console.WriteLine("Exception in Main :");


return null;


}


}






/**//// <summary>


/// 插入根结点


/// </summary>


/// <param name="Nds">TREEVIEW控件ID</param>


private void InitRoot(TreeView Nds)




...{


try




...{


DataView dvTree = new DataView();


TreeNode tmpNd;


//调用生成数据集的DS


DataSet ds = CreateDataSet("select * from TYPE where PID=0");


//把ds的数据填充到dvTree中


dvTree.Table = ds.Tables["Table"];


foreach (DataRowView drvTree in dvTree)




...{


//创建要添加结点


tmpNd = new TreeNode();


tmpNd.Value = drvTree["TID"].ToString();


tmpNd.Text = drvTree["TNAME"].ToString();


//给控件添加根结点


Nds.Nodes.Add(tmpNd);


//设置其自动检查是否有子结点


tmpNd.PopulateOnDemand = true;


tmpNd.SelectAction = TreeNodeSelectAction.Expand;


}


}


catch




...{


//


}


}






/**//// <summary>


/// 添加子结点


/// </summary>


/// <param name="tnd">当前添加的结点</param>


private void AddChild(TreeNode tnd)




...{


try




...{


DataView dvTree = new DataView();


TreeNode tmpNd;


//调用生成数据集的DS


DataSet ds = CreateDataSet("select * from TYPE");


//把ds的数据填充到dvTree中


dvTree.Table = ds.Tables["Table"];


//筛选出当前结点的父结点ID


dvTree.RowFilter = "PID=" + tnd.Value.ToString() + "";


foreach (DataRowView drvTree in dvTree)




...{


//创建要添加结点


tmpNd = new TreeNode();


tmpNd.Value = drvTree["TID"].ToString();


tmpNd.Text = drvTree["TNAME"].ToString();


//添加到当前结点处


tnd.ChildNodes.Add(tmpNd);


//设置其自动搜索是否有子结点


tmpNd.PopulateOnDemand = true;


}


if (tnd.ChildNodes.Count != 0)


tnd.SelectAction = TreeNodeSelectAction.Expand;




}


catch




...{


//


}




}






/**//// <summary>


/// 自动填充结点


/// </summary>


/// <param name="sender"></param>


/// <param name="e"></param>


protected void trvMain_TreeNodePopulate(object sender, TreeNodeEventArgs e)




...{


//给目前结点添加子结点


AddChild(e.Node);


}


protected void btnAddChild_Click(object sender, EventArgs e)




...{


try




...{


clsConn myConn = new clsConn();


myConn.Open();


OleDbDataAdapter cd = new OleDbDataAdapter();


string sqlstr = "insert into TYPE (TNAME,PID) VALUES('" + txtChildName.Text.Trim() + "'," + ddlMain.SelectedValue.ToString() + ")";


cd.SelectCommand = new OleDbCommand(sqlstr, myConn.ChangeType());


cd.SelectCommand.ExecuteNonQuery();


ReSet();


ddlMain.DataBind();


}


catch




...{


//


}


}




/**//// <summary>


/// 刷新TREEVIEW


/// </summary>


private void ReSet()




...{


trvMain.Nodes.Clear();


InitRoot(trvMain);


trvMain.ExpandAll();


}


protected void btnReSet_Click(object sender, EventArgs e)




...{


ReSet();


}


}