Servlet code:



Extra class


1) Is the above code thread-safe?
2) If yes, then is it ok if I put all queries used by my application in DataLoader's static methods and will be executing them from all servlets?

1) That depends on what connections and handler are. I'm guessing that connections is a threadlocal, which would mean that the code is threadsafe (because no non-threadlocal state is maintained).

2) If by query you mean the string that you pass into createQuery, then yes. If you mean the object that's returned from createQuery, then no, as they would all be generated in the classloader thread but available to all threads. As an alternative to statically storing the query strings, you could (or IMO, should) put your queries into your mapping file and use session.getNamedQuery to get them. That will definitely be threadsafe.

tenwit, thanks.

ConnectionHandlers are ThreadLocal.
I meant that I'm going to store all DB related operations (criteria queries, SQL native queries, e.t.c) in one big class DataLoader to separate business logic from DB stuff.
All servlets will be running DataLoader's static methods like getCustomer(), getCustomerData(), getAdvertisement() concurrently.

Is this a good idea?

It's a fairly primitive and brittle way of doing things, but yes, that will work. The normal pattern would be closer to having a separate factory object, frequently called a DAO object, that provides the various load, save methods on a per class basis (you'd have a CustomerDataLoader, AdvertisementDataLoader, etc.). Those DataLoaders could easily use one small DataLoader class with the threadlocals you need. This is a more maintainable way of doing the same thing.

Thank you, I got it.