13.5. Hibernate Services
13.5.1. About Hibernate Services
13.5.2. About Service Contracts
org.hibernate.service.Service. Hibernate uses this internally for some basic type safety.
org.hibernate.service.spi.Startable and org.hibernate.service.spi.Stoppable interfaces to receive notifications of being started and stopped. Another optional service contract is org.hibernate.service.spi.Manageable which marks the service as manageable in JMX provided the JMX integration is enabled.
13.5.3. Types of Service Dependencies
- @
org.hibernate.service.spi.InjectService - Any method on the service implementation class accepting a single parameter and annotated with @
InjectServiceis considered requesting injection of another service.By default the type of the method parameter is expected to be the service role to be injected. If the parameter type is different than the service role, theserviceRoleattribute of theInjectServiceshould be used to explicitly name the role.By default injected services are considered required, that is the start up will fail if a named dependent service is missing. If the service to be injected is optional, therequiredattribute of theInjectServiceshould be declared asfalse(default istrue). org.hibernate.service.spi.ServiceRegistryAwareService- The second approach is a pull approach where the service implements the optional service interface
org.hibernate.service.spi.ServiceRegistryAwareServicewhich declares a singleinjectServicesmethod.During startup, Hibernate will inject theorg.hibernate.service.ServiceRegistryitself into services which implement this interface. The service can then use theServiceRegistryreference to locate any additional services it needs.
13.5.4. The ServiceRegistry
13.5.4.1. About the ServiceRegistry
org.hibernate.service.ServiceRegistry interface. The main purpose of a service registry is to hold, manage and provide access to services.
org.hibernate.service.ServiceRegistryBuilder to build a org.hibernate.service.ServiceRegistry instance.
Example 13.21. Use ServiceRegistryBuilder to create a ServiceRegistry
ServiceRegistryBuilder registryBuilder = new ServiceRegistryBuilder( bootstrapServiceRegistry );
ServiceRegistry serviceRegistry = registryBuilder.buildServiceRegistry();
13.5.5. Custom Services
13.5.5.1. About Custom Services
org.hibernate.service.ServiceRegistry is built it is considered immutable; the services themselves might accept re-configuration, but immutability here means adding/replacing services. So another role provided by the org.hibernate.service.ServiceRegistryBuilder is to allow tweaking of the services that will be contained in the org.hibernate.service.ServiceRegistry generated from it.
org.hibernate.service.ServiceRegistryBuilder about custom services.
- Implement a
org.hibernate.service.spi.BasicServiceInitiatorclass to control on-demand construction of the service class and add it to theorg.hibernate.service.ServiceRegistryBuildervia itsaddInitiatormethod. - Just instantiate the service class and add it to the
org.hibernate.service.ServiceRegistryBuildervia itsaddServicemethod.
Example 13.22. Use ServiceRegistryBuilder to Replace an Existing Service with a Custom Service
ServiceRegistryBuilder registryBuilder = new ServiceRegistryBuilder( bootstrapServiceRegistry );
registryBuilder.addService( JdbcServices.class, new FakeJdbcService() );
ServiceRegistry serviceRegistry = registryBuilder.buildServiceRegistry();
public class FakeJdbcService implements JdbcServices{
@Override
public ConnectionProvider getConnectionProvider() {
return null;
}
@Override
public Dialect getDialect() {
return null;
}
@Override
public SqlStatementLogger getSqlStatementLogger() {
return null;
}
@Override
public SqlExceptionHelper getSqlExceptionHelper() {
return null;
}
@Override
public ExtractedDatabaseMetaData getExtractedMetaDataSupport() {
return null;
}
@Override
public LobCreator getLobCreator(LobCreationContext lobCreationContext) {
return null;
}
@Override
public ResultSetWrapper getResultSetWrapper() {
return null;
}
}
13.5.6. The Bootstrap Registry
13.5.6.1. About the Boot-strap Registry
ClassLoaderService which is a perfect example. Even resolving configuration files needs access to class loading services (resource look ups). This is the root registry (no parent) in normal use.
org.hibernate.service.BootstrapServiceRegistryBuilder class.
13.5.6.2. Using BootstrapServiceRegistryBuilder
Example 13.23. Using BootstrapServiceRegistryBuilder
BootstrapServiceRegistry bootstrapServiceRegistry = new BootstrapServiceRegistryBuilder()
// pass in org.hibernate.integrator.spi.Integrator instances which are not
// auto-discovered (for whatever reason) but which should be included
.with( anExplicitIntegrator )
// pass in a class loader that Hibernate should use to load application classes
.with( anExplicitClassLoaderForApplicationClasses )
// pass in a class loader that Hibernate should use to load resources
.with( anExplicitClassLoaderForResources )
// see BootstrapServiceRegistryBuilder for rest of available methods
...
// finally, build the bootstrap registry with all the above options
.build();
13.5.6.3. BootstrapRegistry Services
org.hibernate.service.classloading.spi.ClassLoaderService
- the ability to locate application classes
- the ability to locate integration classes
- the ability to locate resources (properties files, xml files, etc)
- the ability to load
java.util.ServiceLoader
Note
org.hibernate.integrator.spi.IntegratorService
java.util.ServiceLoader capability provided by the org.hibernate.service.classloading.spi.ClassLoaderService in order to discover implementations of the org.hibernate.integrator.spi.Integrator contract.
/META-INF/services/org.hibernate.integrator.spi.Integrator and make it available on the classpath.
java.util.ServiceLoader mechanism. It lists, one per line, the fully qualified names of classes which implement the org.hibernate.integrator.spi.Integrator interface.
13.5.7. The SessionFactory Registry
13.5.7.1. SessionFactory Registry
org.hibernate.SessionFactory, the instances of services in this group explicitly belong to a single org.hibernate.SessionFactory.
org.hibernate.SessionFactory to be initiated. This special registry is org.hibernate.service.spi.SessionFactoryServiceRegistry
13.5.7.2. SessionFactory Services
org.hibernate.event.service.spi.EventListenerRegistry
- Description
- Service for managing event listeners.
- Initiator
org.hibernate.event.service.internal.EventListenerServiceInitiator- Implementations
org.hibernate.event.service.internal.EventListenerRegistryImpl
13.5.8. Integrators
13.5.8.1. Integrators
org.hibernate.integrator.spi.Integrator is intended to provide a simple means for allowing developers to hook into the process of building a functioning SessionFactory. The org.hibernate.integrator.spi.Integrator interface defines 2 methods of interest: integrate allows us to hook into the building process; disintegrate allows us to hook into a SessionFactory shutting down.
Note
org.hibernate.integrator.spi.Integrator, an overloaded form of integrate accepting a org.hibernate.metamodel.source.MetadataImplementor instead of org.hibernate.cfg.Configuration. This form is intended for use with the new metamodel code scheduled for completion in 5.0.
13.5.8.2. Integrator use-cases
org.hibernate.integrator.spi.Integrator right now are registering event listeners and providing services (see org.hibernate.integrator.spi.ServiceContributingIntegrator). With 5.0 we plan on expanding that to allow altering the metamodel describing the mapping between object and relational models.
Example 13.24. Registering event listeners
public class MyIntegrator implements org.hibernate.integrator.spi.Integrator {
public void integrate(
Configuration configuration,
SessionFactoryImplementor sessionFactory,
SessionFactoryServiceRegistry serviceRegistry) {
// As you might expect, an EventListenerRegistry is the thing with which event listeners are registered It is a
// service so we look it up using the service registry
final EventListenerRegistry eventListenerRegistry = serviceRegistry.getService( EventListenerRegistry.class );
// If you wish to have custom determination and handling of "duplicate" listeners, you would have to add an
// implementation of the org.hibernate.event.service.spi.DuplicationStrategy contract like this
eventListenerRegistry.addDuplicationStrategy( myDuplicationStrategy );
// EventListenerRegistry defines 3 ways to register listeners:
// 1) This form overrides any existing registrations with
eventListenerRegistry.setListeners( EventType.AUTO_FLUSH, myCompleteSetOfListeners );
// 2) This form adds the specified listener(s) to the beginning of the listener chain
eventListenerRegistry.prependListeners( EventType.AUTO_FLUSH, myListenersToBeCalledFirst );
// 3) This form adds the specified listener(s) to the end of the listener chain
eventListenerRegistry.appendListeners( EventType.AUTO_FLUSH, myListenersToBeCalledLast );
}
}

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