If I understand your question, here is a possible solution.

- Encapsulate all the input fields  in a Struts Action form  class
- In this class, have a Collection attribute to accept input from you
variable number  of fields. In Struts 1.1, Collections are
automatically manages by Struts.
- To display the collection in the JSP, and capture user input for the
collection, use tag iterate, possibly also tag nested.
- After form submit, in the Struts Action class  you only have to
iterate through the collection to get field values.