Asp.net 2.0 的 TreeView 控件功能虽说强大,但其客户端控制很逊色,本文将讲解 TreeView 的客户端实现原理,并实现两个个性化操作：
(1) 节点的全部打开和关闭;
TreeNode Expand(or Collapse) all
(2) 只打开一个节点(关闭其他兄弟节点)。
just one node expanded(when a client expand one node all other will collaps)
用记事本打开页面源代码，可以找到一下两个脚本引用：
<script src="/WebUI/WebResource.axd?d=RAQeBcDUNuP9iuS8q3tNEw2&t=633300220640000000" type="text/javascript"></script>
<script src="/WebUI/WebResource.axd?d=JuTdJhq3NM8Jq_RhssAkEg2&t=633300220640000000" type="text/javascript"></script>
将"/WebUI/WebResource.axd?d=RAQeBcDUNuP9iuS8q3tNEw2&t=633300220640000000"拷到地址栏尾，下载脚本，并以 .js 命名，另一个同样操作。分析第二个脚本文件，可以看到TreeView的很多客户端函数，其中关键的一个 TreeView_ToggleNode 就是客户端点击时触发的事件。
要想做个性化的操作，就得从 TreeView_ToggleNode 事件下手。我们无法更改.net封装好的脚本，只有“重写”。所谓的重写就是在原来的函数之后添加一个同名函数(因为js对于同名函数只调用最后一个)。
TreeView_ToggleNode 的原函数：
function TreeView_ToggleNode(data, index, node, lineType, children) {
var img = node.childNodes[0];
var newExpandState;
try {
if (children.style.display == "none") {
children.style.display = "block";
newExpandState = "e";
if ((typeof(img) != "undefined") && (img != null)) {
if (lineType == "l") {
img.src = data.images[15];
}
else if (lineType == "t") {
img.src = data.images[12];
}
else if (lineType == "-") {
img.src = data.images[18];
}
else {
img.src = data.images[5];
}
img.alt = data.collapseToolTip.replace(/\{0\}/, TreeView_GetNodeText(node));
}
}
else {
children.style.display = "none";
newExpandState = "c";
if ((typeof(img) != "undefined") && (img != null)) {
if (lineType == "l") {
img.src = data.images[14];
}
else if (lineType == "t") {
img.src = data.images[11];
}
else if (lineType == "-") {
img.src = data.images[17];
}
else {
img.src = data.images[4];
}
img.alt = data.expandToolTip.replace(/\{0\}/, TreeView_GetNodeText(node));
}
}
}
catch(e) {}
data.expandState.value = data.expandState.value.substring(0, index) + newExpandState + data.expandState.value.slice(index + 1);
}
1. 节点的全部打开和关闭:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>LeftMenu_Tree</title>
</head>
<body bgcolor="#DDEDFD">
<form id="form1" runat="server">
<a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', true)">Expand
All</a> <a href="javascript:TreeviewExpandCollapseAll('<%=TreeView1.ClientID%>', false)">
Collapse All</a>
<asp:TreeView ID="TreeView1" SkinID="tvClass" runat="server" ShowLines="true" NodeWrap="false">
</asp:TreeView>
</form>
</body>
</html>
<script language="javascript">
//-----------------------------------------------------------------------------
function $(s){return document.getElementById(s);}
function isNull(_sVal){return (_sVal == "" || _sVal == null || _sVal == "undefined");}
function TreeviewExpandCollapseAll(treeViewId, expandAll)
{
var displayState = (expandAll == true ? "none" : "block");
var treeView = $(treeViewId);
if(treeView)
{
var treeLinks = treeView.getElementsByTagName("a");
var nodeCount = treeLinks.length;
var flag = true;
for(i=0;i<nodeCount;i++)
{
if(treeLinks[i].firstChild.tagName)
{
if(treeLinks[i].firstChild.tagName.toLowerCase() == "img")
{
var node = treeLinks[i];
var level = parseInt(node.id.substr(node.id.length - 1),10);
var childContainer = GetParentByTagName("table", node).nextSibling;
if(!isNull(childContainer))
{
if(flag)
{
if(childContainer.style.display == displayState)
{
TreeView_ToggleNode(eval(treeViewId +"_Data"),level,node,'r',childContainer);
}
flag = false;
}
else
{
if(childContainer.style.display == displayState)
{
TreeView_ToggleNode(eval(treeViewId +"_Data"),level,node,'l',childContainer);
}
}
}
}
}
}//for loop ends
}
}
function GetParentByTagName(parentTagName, childElementObj)
{
var parent = childElementObj.parentNode;
while(parent.tagName.toLowerCase() != parentTagName.toLowerCase())
{
parent = parent.parentNode;
}
return parent;
}
//-----------------------------------------------------------------------------
</script>