I am not clear but just thinking about following ...
The Reader and writer streams will convert back and forth of UTF format. First write your file into a ByteArrayOutputStream then store it in DB and after reading the data from DB again construct it with Reader.
If you use a standard XML parser and JDBC, isn't encoding taken care of automatically?
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus