在J2SE項目中:

<?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="demo" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>com.ncs.entity.UserInfo</class>
<properties>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.connection.driver_class" value="oracle.jdbc.driver.OracleDriver"/>
<property name="hibernate.connection.url" value="jdbc:oracle:thin:@127.0.0.1:1522:xe"/>
<property name="hibernate.connection.username" value="system"/>
<property name="hibernate.connection.password" value="151923"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
</properties>
</persistence-unit>
</persistence>

注意:配置參數hibernate.hbm2ddl.auto 各個取值的含義

validate? update? create? create-drop

? 這幾個參數的作用主要用于：自動創建? 更新? 驗證數據庫表結構

? 如果不是此方面的需求取none

??validate：加載hibernate時，驗證創建數據庫表結構

??create：每次加載hibernate，重新創建數據庫表結構，這就是導致數據庫表結構丟失的原因

? create-drop：加載hibernate時創建，退出是刪除表結構

??update：加載hibernate自動更新數據庫結構

常見問題排錯:

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：沒有Persistence provider

解決辦法：錯誤提示很明顯:No Persistence provider.

? (1)檢查lib:jar丟失,則將需要的lib添加到classpath中，Jboss使用的是hibernate實現，這些lib在下面的目錄中能找到

jboss-X\common\lib\

? (2)可能provider不對.檢查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沒有初始化成功

解決辦法：?在classpath添加 jnid.properties 文件 （以JBoss為例，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.

程序成功運行，但是數據沒有寫入數據庫

原因：沒有提交數據

解決辦法：em.getTransaction().commit();

附錄

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

?

總結

以上是生活随笔為你收集整理的JPA的persistence.xml的使用及常见问题的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。