JPA 持久化规范----简单应用

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结构~~~~~~~~~

/** * 客户类 * @author Administrator * */@Entity@Table(name="customers")   //对应表名public class Customer {@Id//指定主键生成策略(MSSQL,MYSQL --- identity,  Oracle --- sequence)@GeneratedValue(strategy=GenerationType.IDENTITY)private Integer id;@Column(name="name",length=20)private String name;private Integer age;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}}

JPA 配置文件~~~~~~~~~~~~~~~~~~~~

<?xml version="1.0"?><persistence xmlns="http://java.sun.com/xml/ns/persistence"xmlns:xsi="http://www.w3.org/2001/SMLSchema-instance"version="2.0"><!-- transaction-type: JTA 分布式资源管理事务(多个数据库)   RESOURCE_LOCAL 本地资源管理事务,单个数据库 --><persistence-unit name="jpa" transaction-type="RESOURCE_LOCAL"><!-- 供应商(指定具体的哪款产品) --><!-- 可以去掉,默认搜索/META-INF/services/javax.persistence.spi.PersistenceProvider --><provider>org.hibernate.ejb.HibernatePersistence</provider><!-- 引入实体类 --><!-- 有注解@Entity后,可以去掉 --><class>jpa.persistence.Customer</class><!-- 指定具体的持久化产品自身的属性 --><properties><property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/><property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/jpa"/><property name="hibernate.connection.username" value="root"/><property name="hibernate.connection.password" value="32147"/><property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/><property name="hibernate.hbm2ddl.auto" value="none"/><property name="hibernate.show_sql" value="true"/></properties></persistence-unit></persistence>

测试~~~~~~~~~~~~~~~

public class AppTest {public static void main(String[] args) {//  ###########  原 Hibernate 写法   ###############//Configuration conf = new Configuration();//SessionFactory sf = conf.configure().buildSessionFactory();//Session s = sf.openSession();//Transaction tx = s.beginTransaction();//s.save(null);//tx.commit();//s.close();//创建实体管理器工厂   === 相当于 sessionFactoryEntityManagerFactory emf = Persistence.createEntityManagerFactory("jpa");//创建实体管理器 === 相当于sessionEntityManager em = emf.createEntityManager();//通过实体管理器获得事务对象EntityTransaction tx = em.getTransaction();tx.begin();Customer c = new Customer();c.setName("toma");em.persist(c);tx.commit();em.close();}}

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