如何搭建Eclipse + Mysql + OpenJpa 开发环境？具体的方法步骤介绍。

1、要下载OpenJPA的具体实现，一共8个jar文件，一个都不能少，全部都要导入到Eclipse中

2、下载 mysql-connector-java-5.1.7 ，导入到Eclipse中。

3、实体的ID生成策略一定要设置为 IDENTITY

4、数据库表中的ID字段，一定要设置为 AUTO_INCREMENT

xml配置文件：

<?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=”JPA_Test” transaction-type=”RESOURCE_LOCAL”>
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
<class>andycpp.Customer</class>
<class>andycpp.Address</class>
<class>andycpp.OnlineCustomer</class>
<class>andycpp.Invoice</class>
<class>andycpp.Order</class>
<properties>
<property name=”openjpa.ConnectionURL” value=”jdbc:mysql://localhost:3306/jpa_test”/>
<property name=”openjpa.ConnectionDriverName” value=”com.mysql.jdbc.Driver”/>
<property name=”openjpa.ConnectionUserName” value=”root”/>
<property name=”openjpa.ConnectionPassword” value=”123456″/>
<property name=”openjpa.Log” value=”SQL=TRACE”/>
</properties>
</persistence-unit>
</persistence>