AES Encryption and saving to an XML file

I am using AES encryption in order to ecrypt sensitive data and save
it to an XML file.
There are some sample for AES encryption at
http://www.java2s.com/Code/Java/Security/Basicsymmetricencryptionexample.htm

The problem is that the encypted String can't be saved to XML because
contain illegal for XML characters.

So my question is how can I encypt using AES but in a way so that the
output encrypted String will be possible for saving to an XML file.

Thanks,
Pave;