我已经从数据库生成了 POJO 和相应的 hbm.xml 映射文件。我想测试这是否正常工作，所以我创建了一个简单的 HelloWorld，它读取一个表中的所有数据并打印出来。当我尝试运行它时，会抛出 PersistenceException。这是我的堆栈跟踪：
javax.persistence.PersistenceException: [PersistenceUnit: helloworld] Unable to build EntityManagerFactory
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:924)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:899)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:59)
at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source)
at de.planet.hibernateHelloWorld.HelloWorld.service(HelloWorld.java:51)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:662)
Caused by: org.hibernate.AnnotationException: Use of the same entity name twice: NnsNetzdaten
at org.hibernate.cfg.annotations.EntityBinder.bindEntity(EntityBinder.java:403)
at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:585)
at org.hibernate.cfg.Configuration$MetadataSourceQueue.processAnnotatedClassesQueue(Configuration.java:3512)
at org.hibernate.cfg.Configuration$MetadataSourceQueue.processMetadata(Configuration.java:3466)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1355)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1756)
at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:96)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:914)
... 30 more
Caused by: org.hibernate.DuplicateMappingException: duplicate import: NnsNetzdaten refers to both de.planet.hibernateHelloWorld.data.NnsNetzdaten and NnsNetzdaten (try using auto-import="false")
at org.hibernate.cfg.Configuration$MappingsImpl.addImport(Configuration.java:2646)
at org.hibernate.cfg.annotations.EntityBinder.bindEntity(EntityBinder.java:396)
... 37 more
我直接从 Eclipse Kepler 将应用程序部署到 Glassfish 3 服务器。但是，当我使用 Maven 打包和部署应用程序时，也会出现此问题。
这是我的persistence.xml：
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="helloworld">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.archive.autodetection"
value="class, hbm" />
<property name="hibernate.connection.driver_class"
value="oracle.jdbc.driver.OracleDriver" />
<property name="hibernate.connection.password"
value="**********" />
<property name="hibernate.connection.url"
value="jdbc:oracle:thin:@d11503oracle1.planet-ic.de:1521:XE" />
<property name="hibernate.connection.username"
value="WEMAG_ENET_DEV" />
<property name="hibernate.default_schema" value="WEMAG_ENET_DEV" />
<property name="hibernate.dialect"
value="org.hibernate.dialect.Oracle10gDialect" />
<property name="hibernate.c3p0.max_size" value="30" />
<property name="hibernate.c3p0.min_size" value="5" />
<property name="hibernate.c3p0.idle_test_period"
value="3000" />
<property name="hibernate.c3p0.timeout" value="300" />
<property name="hibernate.c3p0.max_statements"
value="50" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.format_sql" value="true" />
</properties>
</persistence-unit>
</persistence>
每个 POJO 类在类定义之前还有以下注解：
@Entity
@Table(name = "[Table Name]")
我不认为这些是必要的，所以我尝试删除它们，但这会导致各种问题，所以我认为这不是要走的路：p
编辑：它现在有效，请参阅答案，但我不知道为什么。Hibernate 不再检测 hbm.xml 映射数据，因此，由于 POJO 类不包含任何映射数据，它应该无法从数据库中获取数据：-/。