====1===
org.hibernate.MappingException: Unknown entity: cjq.hibernate.tutorial.domain.Event
at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1192)
at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1403)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:117)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:204)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:189)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:757)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:749)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:745)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:352)
at $Proxy4.save(Unknown Source)
at cjq.hibernate.tutorial.web.EventManagerServlet.createAndStoreEvent(EventManagerServlet.java:115)
at cjq.hibernate.tutorial.web.EventManagerServlet.doGet(EventManagerServlet.java:44)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:722)
刚开始用下面的代码：
Configuration cfg = new Configuration().addResource(
"cjq/hibernate/tutorial/domain/Event.hbm.xml").addResource(
"cjq/hibernate/tutorial/domain/Person.hbm.xml");
return new Configuration().configure().buildSessionFactory();
这里有两个不同的Configuration实例。第一个实例有添加映射文件，而第二个没有。且返回的是第二个。
因此会报错。这是个比较低级的错误了。
更改代码为：
Configuration cfg = new Configuration().addResource(
"cjq/hibernate/tutorial/domain/Event.hbm.xml").addResource(
"cjq/hibernate/tutorial/domain/Person.hbm.xml");
//return new Configuration().configure().buildSessionFactory();
return cfg.configure().buildSessionFactory();
这样就不会了。因为用的是同一个Configuration实例了。
补充说明：
当不在hibernate.cfg.xml配置一些相关属性时，
java代码如下：
Configuration cfg = new Configuration() .addClass(org.hibernate.auction.Item.class) .addClass(org.hibernate.auction.Bid.class) .setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLInnoDBDialect") .setProperty("hibernate.connection.datasource", "java:comp/env/jdbc/test") .setProperty("hibernate.order_updates", "true");
注：此处代码引用hibernate学习文档。