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

<!DOCTYPE hibernate-mapping PUBLIC

    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.itcast.vo"><!-- 如果这里配置了包名下面可以不用写 -->

<!--

<hibernate-mapping>

-->

<!--

    <class name="cn.itcast.hibernate3.demo2.Customer" table="customer">

    -->

    <!--

    <class name="cn.itcast.vo.Customer" table="customer">

        -->

            <class name="Customer" batch-size="2" table="customer">

        <!-- 配置唯一标识 -->

        <id name="cid" column="cid">

            <generator class="native"/>

        </id>

        <!-- version标签是版本号 -->

        <version name="version"></version>

        <!-- 配置普通属性 -->

        <property name="cname" column="cname" length="30"/>

        <property name="age" column="age" length="30"/>

        <!-- 建立映射 -->

        <!-- 配置一个集合 <set>的name Customer对象中的关联对象的属性名称. -->

        <!-- 这里把级联去掉  要最简短的配置

        <set name="orders" cascade="save-update" inverse="true">

-->

<set name="orders" cascade="save-update" batch-size="2">

            <!-- <key>标签中column:用来描述一对多多的一方的外键的名称. -->

            <key column="cno"></key>

            <!-- 配置一个<one-to-many>标签中class属性:订单的类的全路径 -->

            <!--

            <one-to-many class="cn.itcast.hibernate3.demo2.Order"/>

            -->

            <one-to-many class="cn.itcast.vo.Order"/>

        </set>

    </class>

    <!-- 命名查询的方式 -->

    <query name="findAll">

    from Customer

    </query>

    <!--  这里要写sql语句

    <sql-query>

    </sql-query>

    -->

</hibernate-mapping>

package cn.itcast.test;

import org.hibernate.LockMode;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.Test;

import cn.itcast.utils.HibernateUtils;

import cn.itcast.vo.Customer;

/**

 *

 * Hibernate的事务管理:

 * @author zhongzh

 *

 */

public class HibernateDemo3 {

    @Test

    /*

     * 使用乐观锁解决丢失更新  也需要两个事务同时操作这条记录。

     */

      public void demo6(){

          Session session = HibernateUtils.openSession();

          Transaction tx = session.beginTransaction();

          Customer customer = (Customer) session.get(Customer.class, 3);

          customer.setAge(26);

          tx.commit();

          session.close();

      }

    @Test

    /*

     * 使用乐观锁解决丢失更新

     */

      public void demo5(){

          Session session = HibernateUtils.openSession();

          Transaction tx = session.beginTransaction();

          Customer customer =  (Customer) session.get(Customer.class, 3);

          customer.setCname("沈明贞");

          tx.commit();

          session.close();

      }

    @Test

    /*

     * 使用悲观锁解决丢失更新  底层执行的是同一个,只不过事务不一样而已

     */

      public void demo4(){

          Session session = HibernateUtils.openSession();

          Transaction tx = session.beginTransaction();

        // 使用悲观锁(排它锁)

            @SuppressWarnings("deprecation")

            Customer customer = (Customer) session.get(Customer.class, 3, LockMode.UPGRADE);

            customer.setAge(32);

          tx.commit();

          session.close();

      }

    @Test

    /*

     * 使用悲观锁解决丢失更新

     */

    public void demo3(){

        Session session = HibernateUtils.openSession();

        Transaction tx = session.beginTransaction();

        // 使用悲观锁(排它锁)

        @SuppressWarnings("deprecation")

        Customer customer = (Customer) session.get(Customer.class, 3, LockMode.UPGRADE);

        customer.setCname("沈明贞");

        tx.commit();

        session.close();

    }

      @Test

      /*

       *

       * 丢失更新的产生

       *

       */

      public void demo2(){

          Session session = HibernateUtils.openSession();

          Transaction tx = session.beginTransaction();

          Customer customer =   (Customer) session.get(Customer.class, 3);

         //再有一个事务去更新customer的年龄

          customer.setAge(30);//持久态对象不用手动调update都可以完成更新

          //System.out.println(customer);

          tx.commit();

          session.close();

      }

  @Test

  /*

   *

   * 丢失更新的产生

   *

   */

  public void demo1(){

      Session session = HibernateUtils.openSession();

      Transaction tx = session.beginTransaction();

      Customer customer =   (Customer) session.get(Customer.class, 3);

      //假设就有一个事务在更新这个customer的名称

      customer.setCname("沈明贞");

      //System.out.println(customer);

      tx.commit();

      session.close();

  }

}