<?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="EjbXmlMappingsPU" // 持久化单元名
    transaction-type="JTA(default)/RESOURCE_LOCAL" // 事务类型
    -->
<persistence-unit name="EjbXmlMappingsPU" transaction-type="JTA">
   <description></description> <!-- 描述 -->
   <provider>oracle.toplink.essentials.PersistenceProvider</provider> <!-- 指定一个持久化提供者 -->
   <jta-data-source>jdbc/MyDataSource</jta-data-source> <!-- 指定JTA数据源 -->
   <non-jta-data-source>jdbc/NonTxMyDataSource</non-jta-data-source> <!-- 指定非JTA数据源 -->
   <mapping-file>META-INF/my_queries.xml</mapping-file> <!-- 指定映射文件 -->
   <mapping-file>META-INF/my_entities.xml</mapping-file>
   <jar-file>my/my-classes.jar</jar-file> <!-- 指定托管类的附加JAR -->
   <class>myclass1</class> <!-- 明确列出的类 -->
   <class>myclass2</class>
   <exclude-unlisted-classes/> <!-- 使本地类不能被加到持久化单元中 -->
   <properties> <!-- 使用提供者属性 -->
    <property name="toplink.logging.level" value="FINE"/>
    <property name="toplink.cache.size.dafault" value="500"/>
   </properties>
</persistence-unit>

</persistence>