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Java JPA Nullity on Attribute

I am working for now with JPA/Static metamodel and appeared to me a doubt.
Is there any many manner to verify on an SingularAttribute/PluralAttribute if the relation is required (e.g. the annotation OneToOne, OneToMany, ManyToOne was annotated with optional=false).
for example
i have this
#OneToOne (optional=false,mappedBy = "recordingIsrc")
public Recording<?> recording;
I tried to check on API, but always the only alternative is go back to the annotation to check the attribute, but this seems to be a workaround instead to be a model verification.
Kind Regards,

This information is not contained in the MetaModel API.
The meta model is not created for your purpose. It's just there for making Criteria API type safe.

JPA - Retrieve all Entity Classes

I need to have a List of clasess that are Persistence Entities, I need have Entity Information, using Reflection API of JPA
I have the EntityManager, But I do not know if that is the way.
I want to do a generic logging for my Entities using a EntityListener. That works well, but I do not have the way to register the listener to all my entities.

Use the JPA2 MetaModel? It has assorted methods to see the entities (or managed types).
Set<javax.persistence.metamodel.EntityType<?>> entityTypes = entityManagerFactory.getMetamodel().getEntities();
for (javax.persistence.metamodel.EntityType entityType : entityTypes){
logger.info(entityType.getName());
logger.info(entityType.getJavaType().getCanonicalName());
logger.info("******************************");
}

Take a look at Configuration#getClassMappings()
Returns: Iterator of the entity mappings currently contained in the configuration.

want to write dynamic domain validation...is it possible to declare annotation #not null dynamically ?

I am writing one model class in spring mvc.
I want to do domain validation.
In domain class I have 3 variables say isABCApplicable,abcValue1,abcValue2:
private Boolean isABCApplicable;
private BigDecimal abcValue1;
private BigDecimal abcValue2;
.......getters and setters.........
Now my aim is :
If isABCApplicable is true then i want to make abcValue1 as
#NotNull
abcValue1
and
#NotNull
abcValue2
Is there any way to achieve this?

Why do you want use annotations?
Create your own DataBinder for your model-object and do all validation in object constructor.
Or if you realy want annotations, you can write your own constraint like #NotNullIfApplicable, see Cross field validation with Hibernate Validator (JSR 303) for details.

I believe this is possible by bytecode instrumentation. ASM is one such tool you can manipulate Java bytecode with. Have a look at http://asm.ow2.org/index.html

JPA Hibernate Typedef

In the project I am using JPA with Hibernate implementation. All the entities are annotation based and listed in persistence.xml.
All Entities are packaged into jar.
I need to define a typedef for few properties(in all the entities) which are a string to a enum type. In DB the Columns is varchar. How can i achieve this?
Can I achieve this by adding hbm.xml and hibernate-cfg.xml?
Thanks in advance.

Straight from the documentation:
#org.hibernate.annotations.TypeDef and
#org.hibernate.annotations.TypeDefs allows you to declare type
definitions. These annotations can be placed at the class or package
level. Note that these definitions are global for the session factory
(even when defined at the class level). If the type is used on a
single entity, you can place the definition on the entity itself.
Otherwise, it is recommended to place the definition at the package
level.

If you can't change the classes but can change the hibernate config, I think you could change hibernate.mapping.precedence to be "hbm,class", and then add hbm files with all the information in the annotations for the relevant classes. There is hbm syntax to specify a UserType or an EnumType. You'd also have to define your UserType class if using that.
You might want to try this out on a test project before taking my word for it, I'm assuming it would work but I don't know for sure.
Copying all of the persistence information from annotations to hbm could be a pain, and would duplicate information. Try if possible to find a way to add the annotations to the classes themselves.

How can I inherit Hibernate filters with annotations?

I'm trying to set up a Hibernate filter with annotations. I would like to specify it in a base class and make all sub classes use it but whenever I try to enable it, Hibernate fails to find the filter. Is it possible at all to inherit filter annotations?

Since 3.5.0 it's at least possible for #MappedSuperclass.
Not sure if that helps you... see: HHH-4332

Are you using the hibernate filter directly, or are you extending the hibernate filter for your own purposes? Annotations aren't inherited by default in Java, although if you were writing the annotation yourself, and I'm assuming hibernate didn't do this on their annotations, you can specify the #Inherited meta-annotation on your annotation to make it inherit. This only works for Type level annotations, though. Also, some people write an annotation manager to simulate full inheritance. You could do something like that, either extend hibernates mechanism or write a preprocessor that adds the annotations where they should have been inherited.

What John Ellinwood wrote is precisely the case. That is why #Filter needs to be specified on all subclasses, at least in Hibernate Annotations 3.4.0-GA.
Furthermore, although that might not be apparent, you will need the same annotation on all mapped collections of that class, if you expect those collections to be susceptible to filtering as well.