Jsp Code to traverse through a folder and print.

i have a requirement in jsp, where i need to iterate through a given folder. then return the file name. the file name should be in the form below.
<li>
Folder
<ul>
<li>
Sub folder 1.1
<ul>
<li>sub folder 1.1.1</li>
<li>sub folder 1.1.2</li>
</ul>
</li>
<li>
Sub folder 1.2
</li>
</ul>
</li>