Java 是否需要persistence.xml文件？

我的开发环境（IBMRAD8+WAS8）抱怨我的项目没有persistence.xml文件。尽管如此，我似乎仍然可以构建和运行我的项目。该文件是必需的吗？如果需要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

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，这个persistence.xml错误是该项目中唯一的错误，因此我很乐意将其删除

谢谢你的帮助

更新 我在文件中搜索persistence.xml，它显示在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EJB项目中的persistence.xml，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>

jdbc/大型机测试ADBUTV2
se.prv.pandora.arendeprocess.entity.PRVNummer
se.prv.pandora.arendeprocess.entity.Ansokan
se.prv.pandora.arendProcess.entity.NatAnsokan
se.prv.pandora.arendProcess.entity.PctAnsokan
se.prv.pandora.arendeprocess.entity.ArendePerson
se.prv.pandora.arendeprocess.entity.NYRegistering
se.prv.pandora.arendeprocess.entity.Anstalld
se.prv.pandora.arendeprocess.entity.Handlaggare
se.prv.pandora.arendProcess.entity.OrgElement
se.prv.pandora.arendeprocess.entity.FysiskHandlaggare
se.prv.pandora.arendeprocess.entity.ANSVRIGHANDLAGGARE
se.prv.pandora.arendeprocess.entity.ANSVRIGFYSKHANDLAGGARE
se.prv.pandora.arendeprocess.entity.TeknikOmrade
se.prv.pandora.arendProcess.entity.Person
se.prv.pandora.arendeprocess.entity.PRVNummerPerson
se.prv.pandora.arendProcess.entity.Notering
se.prv.pandora.arendProcess.entity.Lock
se.prv.pandora.arendeprocess.entity.LandKod
se.prv.pandora.arendeprocess.entity.ARBETSMONTLOG
se.prv.pandora.arendeprocess.entity.SystemTypDel
se.prv.pandora.arendeprocess.entity.ARBETSMONT
se.prv.pandora.arendeprocess.entity.SUBSTATUS
se.prv.pandora.arendeprocess.entity.PatPers
se.prv.pandora.arendProcess.entity.PrvLandP
se.prv.pandora.arendProcess.entity.PkaPerln
se.prv.pandora.arendProcess.entity.PctnPerl
se.prv.pandora.arendeprocess.entity.PersonToPatPersKoppl
se.prv.pandora.arendeprocess.entity.PRVNummerPersonKoppl
se.prv.pandora.arendeprocess.entity.Region
se.prv.pandora.arendeprocess.entity.Historik
se.prv.pandora.arendProcess.entity.Egenskap
真的

---

persistence.xml

文件通常包含与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，因此您不需要显式地拥有这些详细信息，尽管拥有这样的文件通常会使所有与持久性相关的信息都可以在一个位置使用，从而使查找某些设置和配置变得更容易

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>

以上内容摘自。

org.eclipse.persistence.jpa.PersistenceProvider
com.tridenthyundai.ains.domainobject.AccessoriesDO
com.tridenthyundai.ains.domainobject.BranchDO
com.tridenthyundai.ains.domainobject.ContactDO
com.tridenthyundai.ains.domainobject.CustomerDO
com.tridenthyundai.ains.domainobject.FinanceDO
com.tridenthyundai.ains.domainobject.InsuranceDO
com.tridenthyundai.ains.domainobject.MessageDO
com.tridenthyundai.ains.domainobject.NotificationDO
com.tridenthyundai.ains.domainobject.ProductDO
com.tridenthyundai.ains.domainobject.ProductPriceDO
com.tridenthyundai.ains.domainobject.ProductSpecDO
com.tridenthyundai.ains.domainobject.ProductVariantDO
com.tridenthyundai.ains.domainobject.PurchaseDO
com.tridenthyundai.ains.domainobject.ServiceCentreDO
com.tridenthyundai.ains.domainobject.ServiceDO
com.tridenthyundai.ains.domainobject.ServiceTypeDO
com.tridenthyundai.ains.domainobject.UserDO
com.tridenthyundai.ains.domainobject.VisitorDO
假的

org.eclipse.persistence.jpa.PersistenceProvider
com.sapta.hr.domainobject.UserDO
com.sapta.hr.domainobject.EmployeeDO
com.sapta.hr.domainobject.AddressDO
com.sapta.hr.domainobject.EmpDetailDO
com.sapta.hr.domainobject.EmpAccDetailDO
com.sapta.hr.domainobject.ProjectDO
com.sapta.hr.domainobject.CustomerDO
com.sapta.hr.domainobject.EmpAssignmentDO
com.sapta.hr.domainobject.empaoutdo
com.sapta.hr.domainobject.EmpAchievementsDO
com.sapta.hr.domainobject.EmpEmploymentHistoryDO
com.sapta.hr.domainobject.empsortsdo
com.sapta.hr.domainobject.EmpCulturalsDO
com.sapta.hr.domainobject.EmpEducationDO
com.sapta.hr.domainobject.EmpLanguageKnownDO
com.sapta.hr.domainobject.EmpReferencesDO
com.sapta.hr.domainobject.EmpSkillSetDO
com.sapta.hr.domainobject.EmpFamilyBackgroundDO
com.sapta.hr.domainobject.AssetDO
com.sapta.hr.domainobject.AssetTypeDO
com.sapta.hr.domainobject.EmpCTCDO
com.sapta.hr.domainobject.ExpenseDO
com.sapta.hr.domainobject.ExpTypeDO
com.sapta.hr.domainobject.InvoiceDO
com.sapta.hr.domainobject.PayrollDO
com.sapta.hr.domainobject.ProfessionalTaxDO
com.sapta.hr.domainobject.TDSDO
com.sapta.hr.domainobject.VendorDO
com.sapta.hr.domainobject.Bill
<?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>

<?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>