drop index without accessexclusivelock in transaction (JAVA)

Hello,

Through java jdbc, is it possible that we do the following steps without
accessexclusivelock for index:

setautocommit(false);

drop index1, 2,....;
insert millions records
set index1,2...
commit;

Found this post, but it says only within psql block begin/commit, users
are able to do it.
http://stackoverflow.com/questions/19324637/postgres-transaction-seems-to-take-accessexclusivelock-for-no-reason