1. what's the difference between hibernate.properties and hibernate.cfg.xml? I should use one or the other or I can use both? I find that some info appear in both files; but not all. Seem when I do cfg.buildSessionFactory() call, hibernate.properties is used; while when I do cfg.config().buildSessionFactory(), it looks for hibernate.cfg.xml. What's the best practice in using these two files?

2. In my hibernate.properties, I have hibernate.dbcp properies (from samples) defined. However, when I ran, I got the error:
(connection.DBCPConnectionProvider 115 ) could not instantiate DBCP connection pool
java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:394)
at java.lang.Byte.parseByte(Byte.java:122)
at java.lang.Byte.parseByte(Byte.java:79)
at net.sf.hibernate.connection.DBCPConnectionProvider.configure(DBCPConnectionProvider.java:77)
at net.sf.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:83)
at net.sf.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:64)
at net.sf.hibernate.cfg.Configuration.buildSettings(Configuration.java:1091)
at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:737)
at com.gm.brownbear.hibernate.ejb.HibernateDemoManyToMany.run(HibernateDemoManyToMany.java:59)
at com.gm.brownbear.hibernate.ejb.HibernateDemoManyToMany.main(HibernateDemoManyToMany.java:30)
HibernateException Could not instantiate DBCP connection pool

3. So, I comment out the dbcp stuff right now. Run the sample code again. I got another error.

Configuration cfg = null;
SessionFactory sf = null;
Session session = null;
try {
cfg = new Configuration()
.addClass(com.gm.brownbear.hibernate.java.Person.class)
.addClass(com.gm.brownbear.hibernate.java.Flight.class)
.addClass(com.gm.brownbear.hibernate.java.Reservation.class);

// create a session object to the database
sf = cfg.buildSessionFactory();
session = sf.openSession();

It stops right here. sf.openSession() return null.

java.lang.NullPointerException
at com.gm.brownbear.hibernate.ejb.HibernateDemoManyToMany.run(HibernateDemoManyToMany.java:158)
at com.gm.brownbear.hibernate.ejb.HibernateDemoManyToMany.main(HibernateDemoManyToMany.java:30)
Exception in thread "main"

Can someone provides me with help? I checked the forum I did not see any thing similar. So, I guess it must something I did not do correctly. I use the hibernte-2.1.1.

1) Choose one or the other. They are both options you can choose to use to configure the system. (BTW: Don't use both).
2) You have a typo of some form in the DBCP configuration.
3) its not configured correctly.

I suggest you get one (or more) of the examples and have a look at how they are setup. Run them and look at the code etc.

If you read the source code (net.sf.hibernate.connection.DBCPConnectionProvider), you can find that 8 properties are required to define; otherwise, you will get NumberFormatException.

Here are they:

hibernate.dbcp.maxActive
hibernate.dbcp.maxIdle
hibernate.dbcp.maxWait
hibernate.dbcp.whenExhaustedAction
hibernate.dbcp.ps.poolPreparedStatements
hibernate.dbcp.ps.maxActive
hibernate.dbcp.ps.maxIdle
hibernate.dbcp.ps.maxWait
hibernate.dbcp.ps.whenExhaustedAction

Thank you David and Jackey. The connection pool configuration is now working.

However, I still have the problem to go through the sessionFactory.openSession(). I use the sample auction program provided with the hibernate download (v. 2.1.1) When I ran the main, the factory.openSession gives me the following error again:

Setting up some test data
java.lang.NoClassDefFoundError: javax/transaction/Synchronization
at net.sf.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:312)
at net.sf.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:325)
at net.sf.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:333)
at org.hibernate.auction.Main.createTestAuctions(Main.java:283)
at org.hibernate.auction.Main.main(Main.java:365)
Exception in thread "main" 

Based on this error trace, can someone point it out to me where I failed to configure correctly? I did not change anything for the auction sample code, by the way. Should I make some changes in order to run the sample code? Thank you in advance.

Qin

you dont have jta.jar in your classpath

Thank you, Gloeglm. It works now.

Now, I have new problems:

I have these code:
Person qin = new Person();
qin.setPersonId(new Integer(8888));
qin.setFirstName("Qin");
qin.setLastName("Ding");

Flight flight = new Flight();
flight.setFlightId(new Integer(1111));
flight.setName("American");
flight.setDepartureUtc(new java.util.Date());
flight.setArrivalUtc(new java.util.Date());

Reservation reservation = new Reservation();
reservation.setReservationId(1234);
reservation.setRegistrationUtc(new java.util.Date());
reservation.setCommentary("Non-smoking");
java.util.Set reservations = new java.util.HashSet();
reservations.add(reservation);
reservation.setPerson(qin);
reservation.setFlight(flight);

qin.setReservations(reservations);
flight.setReservations(reservations);

session.save(flight);
session.save(qin);
session.save(reservation);
session.flush();
session.connection().commit();

I got this msg in the log:
.....
(impl.SessionImpl 2258) executing flush
(persister.EntityPersister 454 ) Inserting entity: [com.gm.brownbear.hibernate.java.Flight#1111]
(impl.BatcherImpl 192 ) about to open: 0 open PreparedStatements, 0 open ResultSets
(hibernate.SQL 223 ) insert into SYSTEM.FLIGHTS (NAME, DEPARTURE_UTC, ARRIVAL_UTC, FLIGHT_ID) values (?, ?, ?, ?)
Hibernate: insert into SYSTEM.FLIGHTS (NAME, DEPARTURE_UTC, ARRIVAL_UTC, FLIGHT_ID) values (?, ?, ?, ?)
(impl.BatcherImpl 227 ) preparing statement
(persister.EntityPersister 389 ) Dehydrating entity: [com.gm.brownbear.hibernate.java.Flight#1111]

It stops here. No data saved in database. I don't see the exception thrown. What went wrong this time?

Qin

Show the real code (where is tx begining ?)
I recommend you to do