如何在浏览器中将数据显示为xml结构

I am trying to display xml in browser.i have created a xml like

$query2 = "SELECT * FROM user where user_id = 7";
$dbresult = mysqli_query($dbcon,$query2) or die('query error...');

$doc = new DomDocument('1.0');
 $doc->formatOutput = true; 

$root = $doc->createElement('root');
$root = $doc->appendChild($root);

while($row = mysqli_fetch_array($dbresult)) {

  $userId = $doc->createElement('UserId');
  $userId = $root->appendChild($userId);
   $value = $doc->createTextNode($row[0]);
  $value = $userId->appendChild($value);

   $psw = $doc->createElement('Password');
  $psw = $root->appendChild($psw);
   $value = $doc->createTextNode($row[2]);
  $value = $psw->appendChild($value);


} 
echo $doc->saveXML();
$doc->save("test.xml"); 

it displaying just data like

7 pwd123

but i want data like

<xml>
   <root>
     <userId>7</userId>
     <password>pwd123</password>
   </root>
</xml>

what to do for that? thanks

use Right Click -> Show source code command

Your script doesn't set the Content-type header and php sends the default content-type header which usually is Content-type: text/html.
The client therefore assumes that the data is an html document and parses and displays it as such.
And if the client/browser doesn't "know" the tags/elements your document contains (and context matters) http://www.w3.org/TR/html401/appendix/notes.html#notes-invalid-docs applies.

If you "tell" the client that the output is an xml document it will/can/should display it accordingly.

if ( headers_sent() ) {
    // can't set the content-type after output has been sent to the client
    die('error');
}
else {
    header('Content-type: text/xml'); // see http://en.wikipedia.org/wiki/XML_and_MIME
    echo $doc->saveXML();   
}

Change your header content-type text/xml

header('Content-type: text/xml');
$doc->saveXML();

For more details refer http://www.w3schools.com/xml/xml_server.asp