I'm new to Hibernate, using it as an implementation of JPA.

I'm puzzled by something basic. I establish the connection to the DB (MySQL) using the two lines:

EntityManagerFactory emf= Persistence.createEntityManagerFactory("MyPU");
EntityManager em = emf.createEntityManager();

Now, this works fine if the DB server is running. However, if it isn't, Hibernate doesn't seem to handle the situation gracefully. The application exits with an exception trace, written to stderr (not logged):

Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection
at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:637)
at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:41)
at com.magicballbingo.yboard.Main.initializePersistence(Main.java:227)
at com.magicballbingo.yboard.Main.main(Main.java:63)
Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:426)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144)
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:119)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1326)
at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:38)
... 2 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

...



Shouldn't Hibernate be throwing an exception here? I find this very strange. Why is Hibernate writing to stderr, and not logging this? Why does it exit?

Here's what I'd like to do. At application startup, I'd like to test for a connection to the DB server. I'd like to use that connection conn, if I can get it, to query the DB for its configuration, using something like
metaData = conn.getMetaData();

If things aren't right, I'll shut down in an orderly fashion.

Can someone tell me how to do this with Hibernate?

the exception trace you're seeing on stderr IS the exception thrown by hibernate, you should handle that.


It's your application who is shutting down because you didn't manage the exception and also you didn't log it...