I currently have a MonetaryAmount object to represent an amount and currency value. To have Hibernate persist this would be easiest with a CompositeUserType, but I don't like creating a dependency in my MonetaryAmount class on hibernate. Is there a way to create a seperate class to do the mapping and then somehow register this mapping class to handle all MonetaryAmount objects?

Would anyone else find this useful?

Maybe I'm missing something here, but it seems like your missing the point of a UserType. The UserType implementation acts as this buffer between the actual type you want mapped in hibernate.

Basically, you'd have a MonetaryAmount class (the existing class) and MonetaryAmountUserType (or whatever you want to call it. Then you'd map the MonetaryAmount in the hibernate mapping using type="MonetaryAmountUserType". This exists this way exactly for the purpose you mention: avoiding dependencies on hibernate in your business classes.

Yep, I completely missed the point. I thought that my type had to implement the hibernate interface for the mapping to take place. Specifying the type works great.

One other novice question: if I specify that the type is immutable (isMutable() returns false), do I need to implement the setPropertyValues() method of the CompositeUserType interface?

thanks
scott

Yes. isMutable() just means that the property objects internals can not change, not that the property itself can not change (java.util.Date would be mutable for example, a String would not be). This for allowing hibernate to take a shortcut when dirty checking.