non-random ramble » hibernate

Oracle Jdbc Driver 10.2.0.2.0 fails to render Euro (€) when db is set to WE8MSWIN1252 encoding

Jim Barritt — Mon, 08 Nov 2010 16:46:41 +0000

We just spent a few glorious hours or so trawling the internet and writing old skool jdbc code, to discover this little beauty. Simply upgrade to 10.2.0.5 of the jdbc driver and it goes away.

Thanks to this post http://efreedom.com/Question/1-377745/Oracle-JDBC-Euro-Character we discovered our problem.

For the full details on the euro….

http://www.fileformat.info/info/unicode/char/20ac/index.htm

And if your really bored:

http://www.fileformat.info/info/unicode/char/1f47e/index.htm

Hibernate Proxy InstantiationException

Jim Barritt — Fri, 23 Jul 2010 13:39:31 +0000

Changing entities to be lazy loaded led me to the following problem:

@OneToMany(fetch = FetchType.LAZY)

Caused by: org.hibernate.HibernateException: Javassist Enhancement failed: Thing
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:142)
	at org.hibernate.proxy.pojo.javassist.JavassistProxyFactory.getProxy(JavassistProxyFactory.java:72)
	at org.hibernate.tuple.entity.AbstractEntityTuplizer.createProxy(AbstractEntityTuplizer.java:402)
	at org.hibernate.persister.entity.AbstractEntityPersister.createProxy(AbstractEntityPersister.java:3483)
….
Caused by: java.lang.InstantiationException: Thing_$$_javassist_38
	at java.lang.Class.newInstance0(Class.java:340)
	at java.lang.Class.newInstance(Class.java:308)
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:139)

Thanks to Kristian I jumped straight to the problem. From the Hibernate docs:

Cat has a no-argument constructor. All persistent classes must have a default constructor (which can be non-public) so that Hibernate can instantiate them using Constructor.newInstance(). It is recommended that you have a default constructor with at least package visibility for runtime proxy generation in Hibernate.

This should probably read “It is essential….”

Anyway now everything is real lazy so happy days.

Log4J settings for working with Hibernate

Jim Barritt — Fri, 23 Jul 2010 12:28:37 +0000

Hibernate components and relationships

Jim Barritt — Mon, 29 Sep 2008 15:16:32 +0000

Situation: you have a hibernate component which itself has a link to another object (e.g. many-to-one)

When loading, if hibernate is not able to satisfy the dependency, it will NOT set the field for your component.

e.g. we have :