没有可用于“事务可选”的持久性提供程序

Question

我的 AppEngine 项目中出现此错误：

javax.persistence.PersistenceException: No persistence providers available for "transactions-optional" after trying the following discovered implementations: org.datanucleus.api.jpa.PersistenceProviderImpl
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:180)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:70)

jdoconfig.xml

<jdoconfig xmlns="http://java.sun.com/xml/ns/jdo/jdoconfig"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/jdo/jdoconfig http://java.sun.com/xml/ns/jdo/jdoconfig_3_0.xsd">

    <persistence-manager-factory name="transactions-optional">
        <property name="javax.jdo.PersistenceManagerFactoryClass"
            value="org.datanucleus.api.jdo.PersistenceManagerFactoryClass"/>
        <property name="javax.jdo.option.ConnectionURL" value="appengine"/>
        <property name="javax.jdo.option.NontransactionalRead" value="true"/>
        <property name="javax.jdo.option.NontransactionalWrite" value="true"/>
        <property name="javax.jdo.option.RetainValues" value="true"/>
        <property name="datanucleus.appengine.autoCreateDatastoreTxns" value="true"/>
        <property name="datanucleus.appengine.singletonPMFForName" value="true"/>
    </persistence-manager-factory>
</jdoconfig>

这真的很奇怪，因为在我的 jdoconfig.xml 中有这个“事务可选”

Answer 1

显然 JPA（用于获取 EMF）不使用“jdoconfig.xml”（由 JDO 使用）。 JPA 使用“persistence.xml”。建议您在继续之前确定您正在使用的 API