可通过将 XmlDataSource 控件的 XPath 属性设置为 XPath 筛选表达式，来筛选该控件公开的 XML 数据。如果已指定可扩展样式表语言 (XSL) 样式表来转换 XmlDataSource 控件公开的数据，则在转换后会应用 XPath 筛选表达式。
下面的代码示例演示绑定到 TreeView 控件的 XmlDataSource 控件。XML 数据是使用 XPath 查询筛选的。
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void SelectRegion(object sender, EventArgs e)
{
if (RegionDropDownList.SelectedValue == "(Show All)")
PeopleDataSource.XPath = "/People/Person";
else
{
string selectedValue = "";
switch (RegionDropDownList.SelectedValue)
{
case "CA":
selectedValue = "CA";
break;
case "HI":
selectedValue = "HI";
break;
case "WA":
selectedValue = "WA";
break;
default:
// Invalid value.
break;
}
PeopleDataSource.XPath = "/People/Person[Address/Region='" + selectedValue + "']";
}
PeopleTreeView.DataBind();
}
</script>
<html >
<head runat="server">
<title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
<table border="0" ce
