How to call a stored procedure using hibernate?

I am having some problems with hibernate and MySQL. I've been reading but I am getting even more confused, so I imagine you could help me understand what I should do next.

I have a MySQL database in which I added this Stored Procedure (thanks to the Stack Overflow people)

CREATE PROCEDURE BookBed (
OUT oReservaOK boolean,
pPaciente varchar(255),
pHospital bigint(20))
BEGIN
 DECLARE NumLeitosDisponiveis INT;
 DECLARE dt TIMESTAMP;

SET dt = (Select now());
SET NumLeitosDisponiveis = (SELECT AVAILABLEBEDCOUNT FROM HOSPITAL WHERE ID = pHospital); 

IF((SELECT NumLeitosDisponiveis) > 0) THEN 
BEGIN
    START TRANSACTION;

    INSERT INTO RESERVATION(PERSON, HOSPITAL, DATE)
        VALUES (pPaciente, pHospital, dt);

    UPDATE HOSPITAL
        SET AVAILABLEBEDCOUNT = AVAILABLEBEDCOUNT - 1 
    WHERE ID = pHospital;

    SET oReservaOk = true;

    commit;
END;
ELSE 
    SET oReservaOk = false;     
END IF;
END

I've read somewhere that calling functions and procedures using hibernate would be very similar. Then I found (coincidently also in StackOverflow), the code to execute a function using from my java application using Hibernate:

session.doWork(new Work() {
        @Override
          public void execute(Connection connection) throws SQLException {
            CallableStatement call = connection.prepareCall("{ ? = call " + functionName + "(?,?,?)  }");
            call.registerOutParameter( 1, Types.BOOLEAN ); // or whatever it is
            call.setString(2, param1);
            call.setLong(3, param2);
            call.registerOutParameter( 4, Types.BOOLEAN ); // or whatever it is
            call.execute();
            DatabaseManager.this.set开发者_如何学编程Result(call.getBoolean(1)); // propagate this back to enclosing class
          }
        });

I tried to use it but I get different kinds of errors (it depends how I setup the parameters). At the current point in time, I am getting a "No value specified for parameter 3" error because I registered an output parameter. I've searched for more information but I am getting confused because the websites have different approaches and many links to the documentation are broken (links to JBoss web site).

I've read I have to return a cursor as the first out parameter. I am searching the way to do it in MySQL. (But I've read this is an indication that your design is bad) What should I do? I am completely lost... How can I solve it? Should I change the procedure to return my value in some other way?

Thanks, Oscar

There is a mismatch between the signature of your stored procedure and the way you call it. You have to call it as "call BookBed(?, ?, ?)". Also note that it takes only 3 parameters, not 4.