[emsy]

You should definitely focus on one technology, until you feel safe to call yourself an experienced Java developer. Of course you can and should look at other technologies but try not to get distracted until you know the fundamentals of professional (web) development. Once you're confident in a certain technology, picking up a similar technology will be relatively quick and easy. Another reason is that web frameworks are quickly outdated, and learning them to have them in your portfolio doesn't make sens in my opinion.

To paraphrase a common saying: Someone who works 10 years and every year with a different technology has 10x 1 year experience, not 10 years experience.