The org.hibernate.boot.Metadata
是我们感兴趣的,因为它包含PersistentClass
实体绑定。
首先,您需要创建一个Integrator
这将使您能够访问Metadata
:
public class MetadataExtractorIntegrator
implements org.hibernate.integrator.spi.Integrator {
public static final MetadataExtractorIntegrator INSTANCE =
new MetadataExtractorIntegrator();
private Database database;
private Metadata metadata;
public Database getDatabase() {
return database;
}
public Metadata getMetadata() {
return metadata;
}
@Override
public void integrate(
Metadata metadata,
SessionFactoryImplementor sessionFactory,
SessionFactoryServiceRegistry serviceRegistry) {
this.database = metadata.getDatabase();
this.metadata = metadata;
}
@Override
public void disintegrate(
SessionFactoryImplementor sessionFactory,
SessionFactoryServiceRegistry serviceRegistry) {
}
}
如果您使用JPA,可以按如下方式注册:
Map<String, Object> configuration = new HashMap<>();
Integrator integrator = integrator();
if (integrator != null) {
configuration.put("hibernate.integrator_provider",
(IntegratorProvider) () -> Collections.singletonList(
MetadataExtractorIntegrator.INSTANCE
)
);
}
EntityManagerFactory entityManagerFactory = new EntityManagerFactoryBuilderImpl(
new PersistenceUnitInfoDescriptor(persistenceUnitInfo),
configuration
)
.build();
现在,运行以下测试用例时:
Metadata metadata = MetadataExtractorIntegrator.INSTANCE.getMetadata();
for ( PersistentClass persistentClass : metadata.getEntityBindings()) {
Table table = persistentClass.getTable();
LOGGER.info( "Entity: {} is mapped to table: {}",
persistentClass.getClassName(),
table.getName()
);
for(Iterator propertyIterator = persistentClass.getPropertyIterator();
propertyIterator.hasNext(); ) {
Property property = (Property) propertyIterator.next();
for(Iterator columnIterator = property.getColumnIterator();
columnIterator.hasNext(); ) {
Column column = (Column) columnIterator.next();
LOGGER.info( "Property: {} is mapped on table column: {} of type: {}",
property.getName(),
column.getName(),
column.getSqlType()
);
}
}
}
反对以下实体:
我们得到以下输出:
Entity: com.vladmihalcea.book.hpjp.util.providers.entity.BlogEntityProvider$Tag is mapped to table: tag
Property: name is mapped on table column: name of type: varchar(255)
Property: version is mapped on table column: version of type: integer
Entity: com.vladmihalcea.book.hpjp.util.providers.entity.BlogEntityProvider$PostComment is mapped to table: post_comment
Property: post is mapped on table column: post_id of type: bigint
Property: review is mapped on table column: review of type: varchar(255)
Property: version is mapped on table column: version of type: integer
Entity: com.vladmihalcea.book.hpjp.util.providers.entity.BlogEntityProvider$Post is mapped to table: post
Property: title is mapped on table column: title of type: varchar(255)
Property: version is mapped on table column: version of type: integer
Entity: com.vladmihalcea.book.hpjp.util.providers.entity.BlogEntityProvider$PostDetails is mapped to table: post_details
Property: createdBy is mapped on table column: created_by of type: varchar(255)
Property: createdOn is mapped on table column: created_on of type: datetime(6)
Property: version is mapped on table column: version of type: integer
很酷,对吧?
你可以看看这个例子在 GitHub 上以及。