public class WebForm2 : Page
{
public StringBuilder outputQ;
public StringBuilder outputXml;
public DocumentNavigator nav = null;
public HtmlInputFile XmlFile;

public System.Web.UI.WebControls.Xml MyXml;

public System.Web.UI.WebControls.TextBox TextBox1;
public System.Web.UI.WebControls.TextBox TextBox2;
public System.Web.UI.WebControls.TextBox TextBox3;
public System.Web.UI.WebControls.Button Query;
public System.Web.UI.WebControls.Label FileLabel;

public void On_KeyUp(object sender, System.EventArgs e)
{
Response.Write(\"Works\");
}

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//
// Evals true first time browser hits the page
//
}
}

public void Query_Click(object sender, System.EventArgs e)
{
HttpPostedFile xmlfile = XmlFile.PostedFile;
XmlDocument doc = new XmlDocument();
MyXml.Document = new XmlDocument();
// TextBox2.Text=\"\";
// TextBox3.Text=\"\";

if (xmlfile.FileName != String.Empty)
{
try
{
FileLabel.Text= xmlfile.FileName;

MyXml.Document.Load(xmlfile.FileName);
outputXml = new StringBuilder();
XmlTextReader reader = new XmlTextReader (xmlfile.FileName);
ShowDocument();
TextBox3.Text = outputXml.ToString();

outputQ = new StringBuilder();
doc.Load(xmlfile.FileName);
DocumentNavigator nav = new DocumentNavigator(doc);
// Perform the query e.g. \"descendant::book/price\"
XPathQuery(nav, TextBox1.Text);
TextBox2.Text = outputQ.ToString();

}
catch (Exception exp) {
//outputQ.Append(\"</xmp><font color=/\"#FF6600/\">\"+ exp.Message+\"</font><xmp>\");
}
finally {}
}
else if (FileLabel.Text != String.Empty)
{
try
{
MyXml.Document.Load(FileLabel.Text);
outputXml = new StringBuilder();
XmlTextReader reader = new XmlTextReader (FileLabel.Text);
ShowDocument();
TextBox3.Text = outputXml.ToString();

ShowDocument();

outputQ = new StringBuilder();
doc.Load(FileLabel.Text);
DocumentNavigator nav = new DocumentNavigator(doc);
// Perform the query e.g. \"descendant::book/price\"
XPathQuery(nav, TextBox1.Text);
TextBox2.Text = outputQ.ToString();

}
catch (Exception exp) {
outputQ.Append(\"</xmp><font color=/\"#FF6600/\">\"+ exp.Message+\"</font><xmp>\");
}
finally {}
}
}

private void XPathQuery(XmlNavigator navigator, String xpathexpr )
{
try
{
// Save context node position
navigator.PushPosition();
navigator.Select (xpathexpr);
FormatXml(navigator);

// Restore context node position
navigator.PopPosition();
}
catch (Exception e)
{
}
}

//***************************** Navigator ************************************
private void FormatXml (XmlNavigator navigator)
{
while (navigator.MoveToNextSelected())
{
switch (navigator.NodeType)
{
case XmlNodeType.ProcessingInstruction:
Format (navigator, \"ProcessingInstruction\");
break;
case XmlNodeType.DocumentType:
Format (navigator, \"DocumentType\");
break;
case XmlNodeType.Document:
Format (navigator, \"Document\");
break;
case XmlNodeType.Comment:
Format (navigator, \"Comment\");
break;
case XmlNodeType.Element:
Format (navigator, \"Element\");
break;
case XmlNodeType.Text:
Format (navigator, \"Text\");
break;
case XmlNodeType.Whitespace:
Format (navigator, \"Whitespace\");
break;
}
}
outputQ.Append(\"/r/n\");
}

// Format the output
private void Format (XmlNavigator navigator, String NodeType)
{
String value = String.Empty;
String name = String.Empty;

if (navigator.HasChildren)
{
name = navigator.Name;
navigator.MoveToFirstChild();
if (navigator.HasValue)
{
value = navigator.Value;
}
}
else
{
if (navigator.HasValue)
{
value = navigator.Value;
name = navigator.Name;
}
}
outputQ.Append(NodeType + \"<\" + name + \">\" + value);
outputQ.Append(\"/r/n\");
}

// ********************************** XmlReader *****************************
public void ShowDocument ()
{
outputXml = new StringBuilder();
XmlTextReader reader = new XmlTextReader (FileLabel.Text);

while (reader.Read())
{
switch (reader.NodeType)
{
case XmlNodeType.ProcessingInstruction:
Format (reader, \"ProcessingInstruction\");
break;
case XmlNodeType.DocumentType:
Format (reader, \"DocumentType\");
break;
case XmlNodeType.Comment:
Format (reader, \"Comment\");
break;
case XmlNodeType.Element:
Format (reader, \"Element\");
break;
case XmlNodeType.Text:
Format (reader, \"Text\");
break;
case XmlNodeType.Whitespace:
break;
}
}
TextBox3.Text = outputXml.ToString();
}

protected void Format(XmlReader reader, String NodeType)
{
// Format the output
for (int i=0; i < reader.Depth; i++)
{
outputXml.Append(\'/t\');
}

outputXml.Append(reader.Prefix + NodeType + \"<\" + reader.Name + \">\" + reader.Value);

// Display the attributes values for the current node
if (reader.HasAttributes)
{
outputXml.Append(\" Attributes:\");

for (int j=0; j < reader.AttributeCount; j++)
{
outputXml.Append(reader[j]);
}
}
outputXml.Append(\"/r/n\");
}

/// ************************* DOM *********************************
protected void ShowDocument(XmlNode node)
{
if (node != null)
Format (node);

if (node.HasChildNodes)
{
node = node.FirstChild;
while (node != null)
{
ShowDocument(node);
node = node.NextSibling;
}
}
}

// Format the output
private void Format (XmlNode node)
{
if (!node.HasChildNodes)
{
outputXml.Append(\"/t\" + \"<\" + node.Value + \">\");
}

else
{
outputXml.Append(\"<\" + node.Name + \">\");
if (XmlNodeType.Element == node.NodeType)
{
XmlNamedNodeMap map = node.Attributes;
foreach (XmlNode attrnode in map)
outputXml.Append(\" \" + attrnode.Name + \"<\" + attrnode.Value + \"> \");
}
outputXml.Append(\"/r/n\");
}
}
}

下面就是webform2.aspx了
webform2.aspx
---
<%@ Import Namespace=\"System\" %>
<%@ Import Namespace=\"System.IO\" %>
<%@ Assembly Name=\"System.Xml\" %>
<%@ Import Namespace=\"System.Xml\" %>
<%@ Page Language=\"C#\" Inherits=\"WebForm2\" Src=\"WebForm2.cs\" Debug=\"true\" %>

<HTML><HEAD>

<script runat=\"server\" language=\"C#\">
// Put page script here
public void On_KeyUp(object sender, System.EventArgs e)
{
Response.Write(\"Works\");
}

</script>

<!--<link REL=\"STYLESHEET\" HREF=\"default.css\" TYPE=\"text/css\">-->
<TITLE>test</TITLE>
</HEAD>

<BODY >

<form method=\"post\" action=\"WebForm2.aspx\" runat=\"server\" enctype=\"multipart/form-data\">

<div align=\"left\">
<table>
<tr>
<td>XML Document:</td>
<td><input type=file id=\"XmlFile\" runat=server> FileName:</td>
<td><asp:label id=\"FileLabel\" runat=\"server\"></asp:label></td>
</tr>

<tr>
<td>XPath Expression</td>
<td><asp:textbox id=TextBox1 runat=\"server\" Height=\"20\" Width=\"300\" text=\".//text()\" OnKey_Up=\"On_KeyUp\"></asp:textbox></td>
<td><asp:button type=submit OnClick=\"Query_Click\" runat=\"server\" Height=\"20\" Width=\"91\" text=\"Query\"></asp:button></td>
</tr>
</table>

</br>
<table>
<tr><td>Output from Query</td><td>XML Data</td><tr>
<tr><td>Query Display: <asp:dropdownlist runat=\"server\">
<asp:listitem>Descriptive</asp:listitem>
<asp:listitem>XML</asp:listitem>
</asp:dropdownlist>
</td><tr>
<tr>
<td width=\"50%\" valign=\"top\" align=\"left\"><asp:textbox id=TextBox2 runat=\"server\" Height=\"400\" Width=\"350\" TextMode=\"MultiLine\" Rows=\"10\"></asp:textbox></td>
<td width=\"50%\" valign=\"top\" align=\"left\"><asp:xml id=\"MyXml\" transformsource=\"test.xsl\" runat=server/></asp:xml></td>
</tr>
</table>
</div>

<td><asp:textbox id=TextBox3 runat=\"server\" Height=\"1\" Width=\"5\" TextMode=\"MultiLine\" Rows=\"110\"></asp:textbox></td>

</form>

</BODY>
</HTML>