Is it possible to encrypt a column and NOT have to change app code?
This is what Always Encrypted was created for, but you'll have to wait for SQL Server 2016 (and for the jTDS drivers to catch up). 

In the meantime, your Java app could call stored procedures, such that the data is encrypted there. That's really not going to change the fact that the decrypted text is being sent over the wire, but it does mean you can isolate query changes from the app...