How to invoke PostgreSQL function using spring jdbctemplate instead of direct insert query in Java?

I am new to PostgreSQL. I need to call postgresql function from spring jdbctemplate for storing Employee table details. Below is my code in which I am using insert query to store the Employee details. I need to replace insert query with the Postgresql function-"UpdateEmployee".

@Autowired
JdbcTemplate postgressqljdbctemplate;


@Override
public void update(Employee employee) {
String SQL = "insert into employee(Id, name, age, salary) values (?,?,?,?)";
postgressqljdbctemplate.update(SQL, new Object[] { employee.getId(), employee.getName(),
employee.getAge(), employee.getSalary()});
}