JPA的配置文件persistence.xml參數詳解

<?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屬性用於定義持久化單元的名字 (name必選,空值也合法);   
     transaction-type 指定事務類型(可選)    
-->  
<persistence-unit name="unitName" transaction-type="JTA">  
  
   <!-- 描述信息.(可選) -->  
   <description> </description>  
  
   <!-- javax.persistence.PersistenceProvider接口的一個實現類(可選) -->  
   <provider>   </provider>  
  
   <!-- Jta-data-source和 non-jta-data-source用於分別指定持久化提供商使用的JTA和/或non-JTA數據源的全局JNDI名稱(可選) -->  
   <jta-data-source>java:/MySqlDS</jta-data-source>  
   <non-jta-data-source> </non-jta-data-source>  
  
   <!-- 聲明orm.xml所在位置.(可選) -->  
   <mapping-file>product.xml</mapping-file>  
  
   <!-- 以包含persistence.xml的jar文件爲基準的相對路徑,添加額外的jar文件.(可選) -->  
   <jar-file>../lib/model.jar</jar-file>  
  
   <!-- 顯式列出實體類,在Java SE 環境中應該顯式列出.(可選) -->  
   <class>com.domain.User</class>  
   <class>com.domain.Product</class>  
  
   <!-- 聲明是否掃描jar文件中標註了@Enity類加入到上下文.若不掃描,則以下:(可選) -->  
   <exclude-unlisted-classes/>  
  
   <!--   廠商專有屬性(可選)   -->  
   <properties>  
    <!-- hibernate.hbm2ddl.auto= create-drop / create / update -->  
    <property name="hibernate.hbm2ddl.auto" value="update" />  
    <property name="hibernate.show_sql" value="true" />  
   </properties>  
  
</persistence-unit>  
  
</persistence>