java 是否需要文件persistence.xml？
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时间：2020-10-31 02:13:58 来源:igfitidea点击:
Is the file persistence.xml required?
提问by Niklas
My development environment (IBM RAD 8 + WAS 8) is complaining that my project does not have a persistence.xml file. Still it seems that I can build and run my project. Is that file required and if a add one such file to make my project pass validation, what should be in that file?
我的开发环境（IBM RAD 8 + WAS 8）抱怨我的项目没有persistence.xml 文件。看来我仍然可以构建和运行我的项目。是否需要该文件，如果添加一个这样的文件以使我的项目通过验证，该文件中应该包含什么？
The project is a web project that uses session beans and entity beans from other projects and this persistence.xml error is the only error in the project so I'd be glad to get rid of it.
该项目是一个 Web 项目，它使用来自其他项目的会话 bean 和实体 bean，并且这个 persistence.xml 错误是项目中唯一的错误，所以我很乐意摆脱它。
Thanks for any help
谢谢你的帮助
Update
更新
I searched my files for persistence.xml and it showed up in src/ and bin/ of the EJB project while the web project with servlets and jsp does not have a persistence.xml, according to my colleague the web project is using the persistence.xml from the EJB project i.e:
我在我的文件中搜索了persistence.xml，它出现在EJB 项目的src/ 和bin/ 中，而带有servlet 和jsp 的Web 项目没有persistence.xml，据我的同事说，Web 项目正在使用持久性。来自 EJB 项目的 xml 文件，即：
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" 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">
<persistence-unit name="PandoraArendeWeb" transaction-type="JTA">
<jta-data-source>jdbc/Mainframe_TEST_ADBUTV2</jta-data-source>
<class>se.prv.pandora.arendeprocess.entity.PRVNummer</class>
<class>se.prv.pandora.arendeprocess.entity.Ansokan</class>
<class>se.prv.pandora.arendeprocess.entity.NatAnsokan</class>
<class>se.prv.pandora.arendeprocess.entity.PctAnsokan</class>
<class>se.prv.pandora.arendeprocess.entity.ArendePerson</class>
<class>se.prv.pandora.arendeprocess.entity.Nyregistrering</class>
<class>se.prv.pandora.arendeprocess.entity.Anstalld</class>
<class>se.prv.pandora.arendeprocess.entity.Handlaggare</class>
<class>se.prv.pandora.arendeprocess.entity.OrgElement</class>
<class>se.prv.pandora.arendeprocess.entity.FysiskHandlaggare</class>
<class>se.prv.pandora.arendeprocess.entity.AnsvarigHandlaggare</class>
<class>se.prv.pandora.arendeprocess.entity.AnsvarigFysiskHandlaggare</class>
<class>se.prv.pandora.arendeprocess.entity.TeknikOmrade</class>
<class>se.prv.pandora.arendeprocess.entity.Person</class>
<class>se.prv.pandora.arendeprocess.entity.PRVNummerPerson</class>
<class>se.prv.pandora.arendeprocess.entity.Notering</class>
<class>se.prv.pandora.arendeprocess.entity.Lock</class>
<class>se.prv.pandora.arendeprocess.entity.LandKod</class>
<class>se.prv.pandora.arendeprocess.entity.ArbetsMomentLog</class>
<class>se.prv.pandora.arendeprocess.entity.SystemTypDel</class>
<class>se.prv.pandora.arendeprocess.entity.ArbetsMoment</class>
<class>se.prv.pandora.arendeprocess.entity.UnderStatus</class>
<class>se.prv.pandora.arendeprocess.entity.PatPers</class>
<class>se.prv.pandora.arendeprocess.entity.PrvLandP</class>
<class>se.prv.pandora.arendeprocess.entity.PkaPerln</class>
<class>se.prv.pandora.arendeprocess.entity.PctnPerl</class>
<class>se.prv.pandora.arendeprocess.entity.PersonToPatPersKoppl</class>
<class>se.prv.pandora.arendeprocess.entity.PRVNummerPersonKoppl</class>
<class>se.prv.pandora.arendeprocess.entity.Region</class>
<class>se.prv.pandora.arendeprocess.entity.Historik</class>
<class>se.prv.pandora.arendeprocess.entity.Egenskap</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
</persistence-unit>
<!-- <persistence-unit name="PandoraArendeWeb_MSSQL" transaction-type="JTA">
<jta-data-source>jdbc/MSSQL_TEST_XA</jta-data-source>
<class>se.prv.pandora.arendeprocess.entity.PersonSearch</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
</persistence-unit>
-->
</persistence>
回答by npinti
persistence.xmlfiles usually contain details related to your database, such as connection strings and their respective user names and passwords including other ORM related information. These details can be placed in other locations so you need not explicitly have one, although having such a file usually makes all persistence related information available in one place which makes looking up certain settings and configurations easier.
persistence.xml文件通常包含与您的数据库相关的详细信息，例如连接字符串及其各自的用户名和密码，包括其他 ORM 相关信息。这些详细信息可以放在其他位置，因此您不需要明确拥有一个，尽管拥有这样的文件通常可以在一个位置提供所有与持久性相关的信息，这使得查找某些设置和配置更容易。
This is a sample persistence.xmlfile:
这是一个示例persistence.xml文件：
<?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="<PERSISTENCE UNIT NAME>">
<properties>
<!--
<property name="hibernate.ejb.cfgfile" value="/hibernate.cfg.xml"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
-->
<property name="hibernate.archive.autodetection" value="class, hbm"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.connection.password" value="<PASSWORD>"/>
<property name="hibernate.connection.url" value="jdbc:mysql://<HOST IP ADDRESS>/<DB NAME>"/>
<property name="hibernate.connection.username" value="<USERNAME>"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.c3p0.min_size" value="5"/>
<property name="hibernate.c3p0.max_size" value="20"/>
<property name="hibernate.c3p0.timeout" value="300"/>
<property name="hibernate.c3p0.max_statements" value="50"/>
<property name="hibernate.c3p0.idle_test_period" value="3000"/>
</properties>
</persistence-unit>
</persistence>
The above content was taken from here.
以上内容摘自这里。
回答by mohan
<?xml version="1.0" encoding="UTF-8" ?>
<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_2_0.xsd"
version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="AINS" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>com.tridenthyundai.ains.domainobject.AccessoriesDO</class>
<class>com.tridenthyundai.ains.domainobject.BranchDO</class>
<class>com.tridenthyundai.ains.domainobject.ContactDO</class>
<class>com.tridenthyundai.ains.domainobject.CustomerDO</class>
<class>com.tridenthyundai.ains.domainobject.FinanceDO</class>
<class>com.tridenthyundai.ains.domainobject.InsuranceDO</class>
<class>com.tridenthyundai.ains.domainobject.MessageDO</class>
<class>com.tridenthyundai.ains.domainobject.NotificationDO</class>
<class>com.tridenthyundai.ains.domainobject.ProductDO</class>
<class>com.tridenthyundai.ains.domainobject.ProductPriceDO</class>
<class>com.tridenthyundai.ains.domainobject.ProductSpecDO</class>
<class>com.tridenthyundai.ains.domainobject.ProductVariantDO</class>
<class>com.tridenthyundai.ains.domainobject.PurchaseDO</class>
<class>com.tridenthyundai.ains.domainobject.ServiceCentreDO</class>
<class>com.tridenthyundai.ains.domainobject.ServiceDO</class>
<class>com.tridenthyundai.ains.domainobject.ServiceTypeDO</class>
<class>com.tridenthyundai.ains.domainobject.UserDO</class>
<class>com.tridenthyundai.ains.domainobject.VisitorDO</class>
<!-- shouldn't be valid for java SE per specification, but it works for EclipseLink ... -->
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<!-- For Local Testing -->
<!-- <properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://saptalabs:3306/tridenthyundai" />
<property name="javax.persistence.jdbc.user" value="adminuser" />
<property name="javax.persistence.jdbc.password" value="adminuser" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="eclipselink.cache.shared.default" value="false"/>
<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode" value="database" />
<property name="eclipselink.logging.level" value="SEVERE" />
</properties> -->
<!-- For Production -->
</persistence-unit>
</persistence>
回答by Kalaiselvan Velmurugan
<?xml version="1.0" encoding="UTF-8" ?>
<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_2_0.xsd"
version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="saptalabs" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>com.sapta.hr.domainobject.UserDO</class>
<class>com.sapta.hr.domainobject.EmployeeDO</class>
<class>com.sapta.hr.domainobject.AddressDO</class>
<class>com.sapta.hr.domainobject.EmpDetailDO</class>
<class>com.sapta.hr.domainobject.EmpAccDetailDO</class>
<class>com.sapta.hr.domainobject.ProjectDO</class>
<class>com.sapta.hr.domainobject.CustomerDO</class>
<class>com.sapta.hr.domainobject.EmpAssignmentDO</class>
<class>com.sapta.hr.domainobject.EmpAboutDO</class>
<class>com.sapta.hr.domainobject.EmpAchievementsDO</class>
<class>com.sapta.hr.domainobject.EmpEmploymentHistoryDO</class>
<class>com.sapta.hr.domainobject.EmpSportsDO</class>
<class>com.sapta.hr.domainobject.EmpCulturalsDO</class>
<class>com.sapta.hr.domainobject.EmpEducationDO</class>
<class>com.sapta.hr.domainobject.EmpLanguageKnownDO</class>
<class>com.sapta.hr.domainobject.EmpReferencesDO</class>
<class>com.sapta.hr.domainobject.EmpSkillSetDO</class>
<class>com.sapta.hr.domainobject.EmpFamilyBackgroundDO</class>
<class>com.sapta.hr.domainobject.AssetDO</class>
<class>com.sapta.hr.domainobject.AssetTypeDO</class>
<class>com.sapta.hr.domainobject.EmpCTCDO</class>
<class>com.sapta.hr.domainobject.ExpenseDO</class>
<class>com.sapta.hr.domainobject.ExpTypeDO</class>
<class>com.sapta.hr.domainobject.InvoiceDO</class>
<class>com.sapta.hr.domainobject.PayrollDO</class>
<class>com.sapta.hr.domainobject.ProfessionalTaxDO</class>
<class>com.sapta.hr.domainobject.TDSDO</class>
<class>com.sapta.hr.domainobject.VendorDO</class>
<class>com.sapta.hr.domainobject.BillsDO</class>
<class>com.sapta.hr.domainobject.EmpLoseOfPayDO</class>
<!-- shouldn't be valid for java SE per specification, but it works for
EclipseLink ... -->
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<!-- For Local Testing -->
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/hrportal" />
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password" value="root" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="eclipselink.cache.shared.default" value="false" />
<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode"
value="database" />
<property name="eclipselink.logging.level" value="SEVERE" />
</properties>
</persistence-unit>
</persistence>
