问题
I am currently upgrading my Hibernate version to the latest version 5.2.10. I replaced my code in the HibernateUtil for the SessionFactory creation.
4.3.11.Final (Previous):
public class HibernateUtil {
private HibernateUtil() {}
private static SessionFactory sessionFactory;
private static Configuration configuration;
public static Configuration getConfiguration() {
return configuration;
}
private static SessionFactory buildSessionFactory() {
try {
if(sessionFactory == null) {
configuration = new Configuration();
configuration.configure("hibernate.cfg.xml");
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();
sessionFactory = configuration
.buildSessionFactory(serviceRegistry);
}
return sessionFactory;
}
catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return buildSessionFactory();
}
public static Session getSession() {
Session hibernateSession = getSessionFactory().getCurrentSession();
return hibernateSession;
}
public static void shutdown() {
getSessionFactory().close();
}
}
5.2.10 Final (New):
public class HibernateUtil {
private static StandardServiceRegistry registry;
private static SessionFactory sessionFactory;
public static SessionFactory getSessionFactory() {
return buildSessionFactory();
}
public static SessionFactory buildSessionFactory() {
if (sessionFactory == null) {
try {
registry = new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();
MetadataSources sources = new MetadataSources(registry);
Metadata metadata = sources.getMetadataBuilder().build();
sessionFactory = metadata.getSessionFactoryBuilder().build();
} catch (Exception e) {
e.printStackTrace();
shutdown();
}
}
return sessionFactory;
}
public static Session getSession() {
Session hibernateSession = getSessionFactory().getCurrentSession();
return hibernateSession;
}
public static void shutdown() {
if (registry != null) {
StandardServiceRegistryBuilder.destroy(registry);
}
}
}
Now I have a method which would fetch me the list of column names by passing the DB table name as a string. I did it like this before in 4.3.11.Final:
public static List<String> getColumnNames(String tableName) {
List<String> columnList=null;
Map<String, ClassMetadata> map = HibernateUtil.getSessionFactory().getAllClassMetadata();
Iterator<Entry<String, ClassMetadata>> itr = map.entrySet().iterator();
while(itr.hasNext()){
ClassMetadata classMetaData = itr.next().getValue();
AbstractEntityPersister aep = (AbstractEntityPersister) classMetaData;
if(aep.getTableName().split("\\.")[1].equalsIgnoreCase(tableName)){
columnList = new ArrayList<String>();
String[] propertyNames = classMetaData.getPropertyNames();
for(String property : propertyNames){
try {
PersistentClass persistentClass = HibernateUtil .getConfiguration().getClassMapping(classMetaData.getEntityName());
String clmName = ((Column) persistentClass.getProperty(property).getColumnIterator().next()).getName();
columnList.add(clmName);
} catch(NoSuchElementException e){
log.error("Element not found idenfied as : "+property);
} catch(Exception e){
log.error(e.getMessage());
}
}
break;
}
}
return columnList;
}
Now after the upgrade it shows the method getAllClassMetadata as deprecated and am facing difficulty to get the PersistentClass object. I saw a similar question here but I couldn't exactly figure out the solution. What part of my current code do I have to change for my getColumnNames() method to work exactly like before. I referred the documentation and it says to use the EntityManagerFactory.getMetamodel() instead but i can't find suitable reference examples of the same. Also will I have to change the SessionFactory creation mechanism for this?
回答1:
Great question. In fact, I liked it so much that I wrote an article about it.
First, we need to create a new Integrator:
public class MetadataExtractorIntegrator
implements org.hibernate.integrator.spi.Integrator {
public static final MetadataExtractorIntegrator INSTANCE =
new MetadataExtractorIntegrator();
private Database database;
@Override
public void integrate(
Metadata metadata,
SessionFactoryImplementor sessionFactory,
SessionFactoryServiceRegistry serviceRegistry) {
database = metadata.getDatabase();
}
@Override
public void disintegrate(
SessionFactoryImplementor sessionFactory,
SessionFactoryServiceRegistry serviceRegistry) {
}
public Database getDatabase() {
return database;
}
}
Then, we can just configure Hibernate to use it.
If you're using the Hibernate bootstrap mechanism, then you can add it like this:
final BootstrapServiceRegistryBuilder bsrb = new BootstrapServiceRegistryBuilder();
bsrb.enableAutoClose();
Integrator integrator = integrator();
if (integrator != null) {
bsrb.applyIntegrator( integrator );
}
final BootstrapServiceRegistry bsr = bsrb.build();
final StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder(bsr);
If you're bootstrapping with JPA, then you can do it as follows:
protected EntityManagerFactory newEntityManagerFactory() {
PersistenceUnitInfo persistenceUnitInfo = persistenceUnitInfo(
getClass().getSimpleName()
);
Map<String, Object> configuration = new HashMap<>();
configuration.put("hibernate.integrator_provider",
(IntegratorProvider) () -> Collections.singletonList( MetadataExtractorIntegrator.INSTANCE )
);
EntityManagerFactoryBuilderImpl entityManagerFactoryBuilder = new EntityManagerFactoryBuilderImpl(
new PersistenceUnitInfoDescriptor(persistenceUnitInfo), configuration
);
return entityManagerFactoryBuilder.build();
}
Now, when running the following test:
for(Namespace namespace : MetadataExtractorIntegrator.INSTANCE
.getDatabase()
.getNamespaces()) {
for( Table table : namespace.getTables()) {
LOGGER.info( "Table {} has the following columns: {}",
table,
StreamSupport.stream(
Spliterators.spliteratorUnknownSize(
table.getColumnIterator(),
Spliterator.ORDERED
),
false
)
.collect( Collectors.toList())
);
}
}
Hibernate outputs all the currently mapped tables in the log:
Table org.hibernate.mapping.Table(post) has the following columns: [
org.hibernate.mapping.Column(id),
org.hibernate.mapping.Column(title),
org.hibernate.mapping.Column(version)
]
Table org.hibernate.mapping.Table(post_comment) has the following columns: [
org.hibernate.mapping.Column(id),
org.hibernate.mapping.Column(review),
org.hibernate.mapping.Column(version),
org.hibernate.mapping.Column(post_id)
]
Table org.hibernate.mapping.Table(post_details) has the following columns: [
org.hibernate.mapping.Column(id),
org.hibernate.mapping.Column(created_by),
org.hibernate.mapping.Column(created_on),
org.hibernate.mapping.Column(version)
]
Table org.hibernate.mapping.Table(post_tag) has the following columns: [
org.hibernate.mapping.Column(post_id),
org.hibernate.mapping.Column(tag_id)
]
Table org.hibernate.mapping.Table(tag) has the following columns: [
org.hibernate.mapping.Column(id),
org.hibernate.mapping.Column(name),
org.hibernate.mapping.Column(version)
]
That's it!
回答2:
Well finally I did it thank's to Vlad's article. I took the integrator code without any change and modified my HibernateUtil and the getColumns() method. So here's my code:
SessionFactory creation:
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
public static SessionFactory getSessionFactory() {
return buildSessionFactory();
}
private static SessionFactory buildSessionFactory() {
final BootstrapServiceRegistry bootstrapServiceRegistry = new BootstrapServiceRegistryBuilder().enableAutoClose()
.applyIntegrator(MetadataExtractorIntegrator.INSTANCE).build();
final StandardServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder(bootstrapServiceRegistry).configure().build();
return new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
}
public static Session getSession() {
Session hibernateSession = getSessionFactory().getCurrentSession();
return hibernateSession;
}
public static void shutdown() {
getSessionFactory().close();
}
}
Metadata Extractor(Get Column names):
public static List<String> getColumnNames(String tableName) {
List<String> columnList = new ArrayList<>();
for (Namespace namespace : MetadataExtractorIntegrator.INSTANCE.getDatabase().getNamespaces()) {
for (Table table : namespace.getTables()) {
if (table.getName().equalsIgnoreCase(lookupTableName)) {
Iterator<Column> iterator = table.getColumnIterator();
while (iterator.hasNext()) {
columnList.add(iterator.next().getName());
}
break;
}
}
if (!columnList.isEmpty())
break;
}
return columnList;
}
回答3:
An easier way to get column name with hibernate 5
final AbstractEntityPersister classMetadata = (AbstractEntityPersister) sessionFactory.getClassMetadata(clazz)
final String[] names = classMetadata.getPropertyColumnNames(property)
来源：https://stackoverflow.com/questions/43604928/hibernate-upgrade-to-5-2-session-factory-creation-and-replacing-persistentclas