I'm new to JavaEE and I'm trying to write a servlet with a simple interface with MySQL. This servlet actually read the db without any problems but actually it doesn't write any change on db.
I've read the JavaEE tutorial but I cannot find useful thinghs about persistence in servlets.
My code is that:
The first two lines works properly because the value printed changes but the db remain unchanged.
This is the autogenerated code from NetBeans for the persist method:
but also a simple em.persist(object) doesn't work.
Can someone help me please? I use NetBeans with glassfish for develop.
Now I've try to create a new servlet, very very simple:
This is the error:
javax.persistence.PersistenceException: No Persistence provider for EntityManager named FluidoDemoWebPU: Provider named org.hibernate.ejb.HibernatePersistence threw unexpected exception at create EntityManagerFactory:
javax.persistence.PersistenceException: [PersistenceUnit: FluidoDemoWebPU] Unable to build EntityManagerFactory
I think there may be a couple of paths to look into:
- location? where is it in your app structure? META-INF?
- <class> </class> i think you need your class or package for your persistent entities declared here
- Hibernate; There may be some properties that need to be configured because you are specifically using the Hibernate provider.
Also, just something you may also want to do:
- extract your persistence calls to another class that you call from your Servlet.
- then you can write a unit test on that class to make sure the persistence is working.