Hibernate 菜鸟教程 18 乐观锁

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简介

模型对象

public class Product {
private Long id;
private String name;
private Integer number;// 库存数量
// 定义为私有字段
//只能在Product类内部修改, 这里是直接由Hibernate管理的
private Integer version;

映射文件

<class name="Product">
<id name="id">
<generator class="native" />
</id>
<!-- 私有字段access="field"配置 -->
<version name="version" access="field" />
<property name="name" />
<property name="number" />
</class>

测试类

package com.jege.hibernate.z_optimistic_lock;

import org.hibernate.Session;
import org.hibernate.StaleObjectStateException;
import org.junit.Before;
import org.junit.Test;

public class MainTest {
@Before
public void save() throws Exception {
Product product = new Product();
product.setName("xxxx");
product.setNumber(10);

Session session = HibernateUtils.getSession();
session.beginTransaction();
session.save(product);
session.getTransaction().commit();
session.close();
}

// 模拟2个事务在进行毫秒级别update操作
@Test
public void update() throws Exception {
try {
Session session1 = HibernateUtils.getSession();
Session session2 = HibernateUtils.getSession();
session1.beginTransaction();
session2.beginTransaction();

Product product = (Product) session1.get(Product.class, 1L);
product.setNumber(product.getNumber() - 8);
Product product2 = (Product) session2.get(Product.class, 1L);
product2.setNumber(product2.getNumber() - 5);

session2.update(product2);
session1.update(product);

session1.getTransaction().commit();
session2.getTransaction().commit();
session1.close();
session2.close();
} catch (StaleObjectStateException e) {
Session session3 = HibernateUtils.getSession();
Product product = (Product) session3.get(Product.class, 1L);
System.out.println("库存已经改变，请重新刷新再次购买:" + product.getNumber());
}
}
}

源码地址