You can check if a connection broke during a query by the looking the error codes or messages of the SQLException for FATAL errors rather than normal SQLExceptions. These codes/messages can be vendor specific, e.g.

<exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter</exception-sorter-class-name>

For

FATAL

errors the connection will be closed.