With
tomcat the default file location is /bin directory, its not a good idea to place the work files under the bin directory - because not all servlet containers can read it.
My idea could be create a directory xmlfiles under web-inf and refer its location in web.xml file
<context-param>
<param-name>xmlfileloc</param-name>
<param-value>/web-inf/xmlfiles</param-value>
<description>Default xml file location</description>
</context-param>
Now in ur servlet try to get this parameters with the following code
String xmlfileloc = getServletContext().getInitParameter("xmlfileloc");