org.hibernate.ejb.HibernatePersistence com.ncs.entity.UserInfo
注意:配置参数hibernate.hbm2ddl.auto 各个取值的含义
validate update create create-drop
这几个参数的作用主要用于：自动创建 更新 验证数据库表结构
如果不是此方面的需求取none
validate：加载hibernate时，验证创建数据库表结构
create：每次加载hibernate，重新创建数据库表结构，这就是导致数据库表结构丢失的原因
create-drop：加载hibernate时创建，退出是删除表结构
update：加载hibernate自动更新数据库结构
常见问题排错:
1.
Exception in thread "main" javax.persistence.PersistenceException: No Persistence provider for EntityManager named HelloTitan at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:56) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34) at Main.main(Main.java:10)
原因：没有Persistence provider
解决办法：错误提示很明显:No Persistence provider.
(1)检查lib:jar丢失,则将需要的lib添加到classpath中，Jboss使用的是hibernate实现，这些lib在下面的目录中能找到
jboss-X\common\lib\
(2)可能provider不对.检查xml文件里面的provider
2.
Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: HelloTitan] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677) at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34) at Main.main(Main.java:10) Caused by: org.hibernate.HibernateException: Could not find datasource at org.hibernate.connection.DatasourceConnectionProvider.configure(DatasourceConnectionProvider.java:79) at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:137) at org.hibernate.ejb.InjectionSettingsFactory.createConnectionProvider(InjectionSettingsFactory.java:29) at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:89) at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2101) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1325) at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669) ... 4 more Caused by: javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file: java.naming.factory.initial at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:645) at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:288) at javax.naming.InitialContext.getURLOrDefaultInitCtx(InitialContext.java:325) at javax.naming.InitialContext.lookup(InitialContext.java:392) at org.hibernate.connection.DatasourceConnectionProvider.configure(DatasourceConnectionProvider.java:75) ... 11 more
原因：JNDI没有初始化成功
解决办法： 在classpath添加 jnid.properties 文件 （以JBoss为例，配置如下）
java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces java.naming.provider.url=127.0.0.1:1099
3.
程序成功运行，但是数据没有写入数据库
原因：没有提交数据
解决办法：em.getTransaction().commit();
附录
Hibernate SQL方言 (hibernate.dialect)
| RDBMS | 方言 |
|---|---|
| DB2 | org.hibernate.dialect.DB2Dialect |
| DB2 AS/400 | org.hibernate.dialect.DB2400Dialect |
| DB2 OS390 | org.hibernate.dialect.DB2390Dialect |
| PostgreSQL | org.hibernate.dialect.PostgreSQLDialect |
| MySQL | org.hibernate.dialect.MySQLDialect |
| MySQL with InnoDB | org.hibernate.dialect.MySQLInnoDBDialect |
| MySQL with MyISAM | org.hibernate.dialect.MySQLMyISAMDialect |
| Oracle (any version) | org.hibernate.dialect.OracleDialect |
| Oracle 9i/10g | org.hibernate.dialect.Oracle9Dialect |
| Sybase | org.hibernate.dialect.SybaseDialect |
| Sybase Anywhere | org.hibernate.dialect.SybaseAnywhereDialect |
| Microsoft SQL Server | org.hibernate.dialect.SQLServerDialect |
| SAP DB | org.hibernate.dialect.SAPDBDialect |
| Informix | org.hibernate.dialect.InformixDialect |
| HypersonicSQL | org.hibernate.dialect.HSQLDialect |
| Ingres | org.hibernate.dialect.IngresDialect |
| Progress | org.hibernate.dialect.ProgressDialect |
| Mckoi SQL | org.hibernate.dialect.MckoiDialect |
| Interbase | org.hibernate.dialect.InterbaseDialect |
| Pointbase | org.hibernate.dialect.PointbaseDialect |
| FrontBase | org.hibernate.dialect.FrontbaseDialect |
| Firebird | org.hibernate.dialect.FirebirdDialect |