利用TreeView控件動態生成無限級樹 


項目需要，有一個樹形菜單需要動態生成，聯想到TreeView控件，決定用TreeView來實現

首先注意到了TreeView控件有一個屬性TreeNodeSrc
這個屬性可以指定一個固定格式的xml文件
<?xml version="1.0" encoding="utf-8" ?> 
<TREENODES>
    <TREENODE text="aaaaaaaa" CheckBox="true"></TREENODE>
    <TREENODE text="bbbbbbbb" CheckBox="true"></TREENODE>
    <TREENODE text="cccccccccc" EXPANDED="true" CheckBox="true">
        <TREENODE text="ddddddddd" CheckBox="true"></TREENODE>
        <TREENODE text="eeeeeeeee" CheckBox="true"></TREENODE>
    </TREENODE>
    <TREENODE text="fffffffffffff" CheckBox="true"></TREENODE>
</TREENODES>于是就想把數據庫里的文件讀出來寫入一個xml文件中，然后再進行綁定
既然是無限級菜單，肯定要用到遞歸來實現，于是就寫了一個如下的遞歸算法
private void CreateXml(XmlDocument objXMLDoc, XmlElement objRootElem, int belong)
        {
            //Get DataSet 這里的DataSet具體獲取方法我省略掉了
            DataSet ds = new DataSet();
            
            foreach(DataRow dr in ds.Tables[0].Rows)
            {
                //Create ChildNode TreeNode
                XmlElement objXmlElem = objXMLDoc.CreateElement("TREENODE");
                objRootElem.AppendChild(objXmlElem);

                //Create Attributes Text
                XmlAttribute objXmlAttText = objXMLDoc.CreateAttribute("Text");
                objXmlAttText.Value = dr["text"].ToString().Trim();
                objXmlElem.SetAttributeNode(objXmlAttText);

                //Create Attributes CheckBox
                XmlAttribute objXmlAttCB = objXMLDoc.CreateAttribute("CheckBox");
                objXmlAttCB.Value = "True";
                objXmlElem.SetAttributeNode(objXmlAttCB);

                int id = int.Parse(dr["id"].ToString().Trim());
                CreateXml(objXMLDoc, objXmlElem, id);
            }
        }
然后用下面的方法來實現綁定
private void BindXmlTree()
        {
            //Create Xml File
            XmlDocument objXmlDoc = new XmlDocument();

            //Insert Xml Declaration
            XmlDeclaration objXmlDeclare = objXmlDoc.CreateXmlDeclaration("1.0", "UTF-8", "yes");
            objXmlDoc.InsertBefore(objXmlDeclare, objXmlDoc.DocumentElement);

            XmlElement objRootElem = objXmlDoc.CreateElement("TREENODES");
            objXmlDoc.AppendChild(objRootElem);

            CreateXml(objXmlDoc, objRootElem, 0);

            objXmlDoc.Save("E:\\TreeMenu.xml");
            TreeView2.TreeNodeSrc = "TreeMenu.xml";
        }
到最后兩行我就停住了，因為問題出現了
生成的objXmlDoc文件不知道用什么方式才能綁定上TreeNodeSrc
我試了試直接 TreeView2.TreeNodeSrc = objXmlDoc;
可是TreeNodeSrc是String型的數據，沒辦法
有沒有什么方法可以不保存這個objXmlDoc文件而直接綁定呢？

于是就換了個辦法來實現
TreeView有一個節點控件叫TreeNode，直接把數據給TreeNode上


private void CreateTree(int belong, Microsoft.Web.UI.WebControls.TreeNode rootnode)
        {
            DataSet ds = new DataSet();

            foreach(DataRow dr in ds.Tables[0].Rows)
            {
                Microsoft.Web.UI.WebControls.TreeNode treenode = new Microsoft.Web.UI.WebControls.TreeNode();
                treenode.Text = dr["text"].ToString().Trim();
                treenode.CheckBox = true;
                treenode.Expanded = true;
                rootnode.Nodes.Add(treenode);

                int id = int.Parse(dr["id"].ToString().Trim());
                CreateTree(id, treenode);
            }
        }
用的是一樣的遞歸思想，而且我發現這樣做還比較簡單一些，很多TreeNode自帶的屬性很方便修改
如果用Xml還要手動去添加每一個屬性，麻煩
在PageLoad里觸發這個方法
private void Page_Load(object sender, System.EventArgs e)
        {
            Microsoft.Web.UI.WebControls.TreeNode rootnode = new Microsoft.Web.UI.WebControls.TreeNode();
            rootnode.Expanded = true;
            TreeView2.Nodes.Add(rootnode);
            CreateTree(0, rootnode);
        }注意，這里為了實現遞歸，不得不添加一個空的根節點rootnode

這樣就算大致實現了
另，數據庫里的數據格式是這樣的
-----------------------------------------
id                    text                     belong
1                    aaaa                    0
2                    bbbb                   0
3                    cccc                    0
4                    dddd                    1
5                    eeee                    2
6                    ffff                        4



==========================================


private void InitTree(TreeNodeCollection Nds,string parentId) 
{ 
TreeNode tmpNd; 
DataRow[] rows = data.Tables[0].Select("ParentId='" + parentId + "'"); 
foreach(DataRow row in rows) 
{ 
tmpNd = new TreeNode(); 
tmpNd.ID = row["NodeId"].ToString(); 
tmpNd.Text = row["NodeName"].ToString(); 
tmpNd.NavigateUrl = row["Url"].ToString(); 
Nds.Add(tmpNd); 
if (row["NodeId"].ToString()!="2") 
InitTree(tmpNd.Nodes, tmpNd.ID); 
} 

============================================



# re: 利用TreeView控件動態生成無限級樹  回復    
2006-01-27 00:31 by QuickTech 
Private Sub LoadTrv() 
Dim Root As New Microsoft.Web.UI.WebControls.TreeNode 
Root.Text = "ALL：" 
Root.ImageUrl = "../images/trv_root.gif" 
Root.SelectedImageUrl = "../images/trv_root.gif" 
Root.ExpandedImageUrl = "../images/trv_root.gif" 

Dim db As New DB 
Dim con As SqlClient.SqlConnection = New SqlClient.SqlConnection(db.Constr) 
Dim dr As SqlClient.SqlDataReader 
Dim SQL As String = "select Floor_value,Floor_Title from basic_floor order by floor_value" 
Dim cmd As SqlClient.SqlCommand = New SqlClient.SqlCommand(SQL, con) 
con.Open() 
dr = cmd.ExecuteReader 
While dr.Read 
Dim FloorNd As New Microsoft.Web.UI.WebControls.TreeNode 
FloorNd.Text = dr("Floor_value") & ":" & dr("Floor_Title") 
FloorNd.ImageUrl = "../images/TrvST2.bmp" 
FloorNd.SelectedImageUrl = "../images/trvst10.bmp" 
FloorNd.ExpandedImageUrl = "../images/trvst1.bmp" 
Root.Nodes.Add(FloorNd) 
End While 
dr.Close() 
con.Close() 
con.Dispose() 
cmd.Dispose() 
End Sub 

為什么我的代碼不能顯示呢?????????
# re: 利用TreeView控件動態生成無限級樹  回復    
2006-01-27 00:34 by QuickTech 
對不起 
我的根都沒加 
問題解決了