SQL Server Stored Procedure into Java using Hibernate -

please, me on below stuff?

i have stored procedure has business logic need convert java using hibernate per customer requirement.

and know stored procedure improve performance customer need, doing this, convert our application product.

in stored procedure has lot of temp tables involved lot of joins actual physical tables(which has more 50000 records), trying have many list have data has in temp table , iterate list, sure affect performance.

could please let me know anyway can achieve steps involved in stored procedure needs convert java.

stored procedure in sql server, later have plan migrate oracle , couldn't use native sql here.