Hello

Try to assign the contents of your form parameters to variables...

Code:
<%@ page import="java.util.Map"%>
<%
Map params = request.getParameterMap();
String userName = "";
String fileName = "";
try{
  userName = ((String[])params.get("username"))[0];
}catch(Exception e){}
try{
  fileName = ((String[])params.get("filename"))[0];
...