XSLT Vs File I/O ReadWrite

I have a result object in java, which i am using to create xml and also to create html file.

I am using JAXB for Marshalling/Unmarshalling for xml, where as I am using File I/O for creating html using java object. What is the best approach to create html file.

1. Use of File I/O operation

or

2. Use of XSLT to transform xml to html.

The result data will be very huge. what will be the best approach in this case.

Thoughts!