JavaEE学习之JPA中配置文件persistence.xml

下面是我从网上找到的关于JPA配置文件persistence.xml的相关描述：

 <?xml version="1.0" encoding="UTF-8"?>  

 <persistence version="1.0"
 xmlns:persistence="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 persistence_1_0.xsd ">  

 <!--
      Name属性用于定义持久化单元的名字 (name必选,空值也合法);
      transaction-type 指定事务类型(可选)
 -->
 <persistence-unit name="LMS" transaction-type="JTA">  

    <!-- 描述信息.(可选) -->
    <description> </description>  

    <!-- javax.persistence.PersistenceProvider接口的一个实现类(可选) -->
    <provider>   </provider>  

    <!-- Jta-data-source和 non-jta-data-source用于分别指定持久化提供商使用的JTA和/或non-JTA数据源的全局JNDI名称(可选) -->
    <jta-data-source>java:/LMSNGDataSource_UW</jta-data-source>
    <non-jta-data-source> </non-jta-data-source>  

    <!-- 声明orm.xml所在位置.(可选) -->
    <mapping-file>product.xml</mapping-file>  

    <!-- 以包含persistence.xml的jar文件为基准的相对路径,添加额外的jar文件.(可选) -->
    <jar-file>../lib/model.jar</jar-file>  

    <!-- 显式列出实体类,在Java SE 环境中应该显式列出.(可选) -->
    <class>com.domain.User</class>
    <class>com.domain.Product</class>  

    <!-- 声明是否扫描jar文件中标注了@Enity类加入到上下文.若不扫描,则如下:(可选) -->
    <exclude-unlisted-classes>true</exclude-unlisted-classes>
   <!--可选 -->
   <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
    <!--   厂商专有属性(可选)   -->
    <properties>
     <!-- hibernate.hbm2ddl.auto= create-drop / create / update -->
     <property name="hibernate.cache.use_second_level_cache"
                 value="true" />
     <property name="hibernate.cache.use_query_cache" value="true" />
     <property name="hibernate.hbm2ddl.auto" value="update" />
     <property name="hibernate.show_sql" value="true" />
    </properties>  

 </persistence-unit>  

 </persistence>