asp.net 2.0中TREEVIEW中动态增加结点

来源：互联网发布：淘宝那个小女孩编辑：程序博客网时间：2024/06/06 02:51

在asp.net 2.0中，要动态从数据库中取出内容，动态增加结点，其实不难，比如以SQL SERVER 2000的PUBS数据库为例子，要以树型列表方式，取出作者，做为根结点，然后取出每位作者写过什么书，作为子结点，可以这样

<%@ Page Language="C#"%>

<%@ Import Namespace="System.Data"%>

<%@ Import Namespace="System.Data.SqlClient"%>

<%@ Import Namespace="System.Configuration"%>

<!DOCTYPE htmlPUBLIC"-//W3C//DTD XHTML 1.1//EN""http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<title>Dynamic Population of the TreeView Control</title>

void Node_Populate(object sender,

System.Web.UI.WebControls.TreeNodeEventArgs e)

{

if(e.Node.ChildNodes.Count == 0)

{

switch( e.Node.Depth )

{

case 0:

FillAuthors(e.Node);

break;

case 1:

FillTitlesForAuthors(e.Node);

break;

}

void FillAuthors(TreeNode node)

{

string connString = System.Configuration.ConfigurationSettings.

ConnectionStrings["NorthwindConnnection"].ConnectionString;

SqlConnection connection = new SqlConnection(connString);

SqlCommand command = new SqlCommand("Select * From

authors",connection);

SqlDataAdapter adapter = new SqlDataAdapter(command);

DataSet authors = new DataSet();

adapter.Fill(authors);

if (authors.Tables.Count > 0)

{

foreach (DataRow row in authors.Tables[0].Rows)

{

TreeNode newNode = new

TreeNode(row["au_fname"].ToString() + " " +

row["au_lname"].ToString(),

row["au_id"].ToString());

newNode.PopulateOnDemand = true;

newNode.SelectAction = TreeNodeSelectAction.Expand;

node.ChildNodes.Add(newNode);

}

void FillTitlesForAuthors(TreeNode node)

{

string authorID = node.Value;

string connString = System.Configuration.ConfigurationSettings.

ConnectionStrings["NorthwindConnnection"].ConnectionString;

SqlConnection connection = new SqlConnection(connString);

SqlCommand command = new SqlCommand("Select T.title,

T.title_id From titles T" +

" Inner Join titleauthor TA on

T.title_id = TA.title_id " +

" Where TA.au_id = '" + authorID + "'", connection);

SqlDataAdapter adapter = new SqlDataAdapter(command);

DataSet titlesForAuthors = new DataSet();

adapter.Fill(titlesForAuthors);

if (titlesForAuthors.Tables.Count > 0)

{

foreach (DataRow row in titlesForAuthors.Tables[0].Rows)

{

TreeNode newNode = new TreeNode(

row["title"].ToString(), row["title_id"].ToString());

newNode.PopulateOnDemand = false;

newNode.SelectAction = TreeNodeSelectAction.None;

node.ChildNodes.Add(newNode);

}

</script>

</head>

<body>

<div>

<asp:TreeViewRunat="Server" ExpandImageUrl="Images/closed.gif"

CollapseImageUrl="Images/open.gif"

OnTreeNodePopulate="Node_Populate" ID="tvwauthors">

<Nodes>

<asp:TreeNodeText="Authors" PopulateOnDemand=true

Value="0"/>

</Nodes>

</asp:TreeView>

</div>

</form>

</body>

</html>

其中，注意ontreenodepopulate事件，是在展开树的结点时发生的，这里定义了自定义的NODE_POPULATE,在node_populate中，检查当前结点的深度，如果是0，就是根结点，于是就调用FillAuthors过程，取出所有的作者，如果深度是1，则是叶子结点，调用FillTitlesForAuthors过程。其中，要注意它们中的动态建立树结点的过程，如：
TreeNode newNode = new TreeNode(row["au_fname"].ToString() + " " +

row["au_lname"].ToString(),

row["au_id"].ToString());

newNode.PopulateOnDemand = true;

newNode.SelectAction = TreeNodeSelectAction.Expand;

node.ChildNodes.Add(newNode);
其中， popluateondemand属性表明，该结点会动态扩展。