How to set transaction isolation level for the given transaction only.

In database server, it has a default isolation level,  and if we want to use

a different one, we can easily do:

begin;

set transaction isolation level xx; 

commit; 

We can see that the isolation level is set at the transaction level.  However when I

check the API,  looks I can only set it at *connection* level via Connection.setTransactionIsolation(x);  If I want to rollback the original, I have

to remember to reset it after this transaction which would be boring in practice. 

What would be the best practice for this?