Hibernate基于version的乐观锁

淩亂°似流年 2022-05-23 00:09 193阅读 0赞

在Hibernate中，主要由Hibernate提供的版本控制功能来实现乐观锁定。Hibernate为乐观锁提供了两种实现，分别基于version的实现和基于timestamp的实现。version元素利用一个递增的整数来跟踪数据表中记录的版本；而timestamp元素则用时间来跟踪数据库表中记录的版本。

#####  #####

##### accounts表结构 #####

![20180529171141492][]

##### 创建实体类 #####

package com.dwx.models;
    public class Accounts {
    	private int id;
    	private String username;
    	private double money;
    	private int version;
    	public int getId() {
    		return id;
    	}
    	public void setId(int id) {
    		this.id = id;
    	}
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public double getMoney() {
    		return money;
    	}
    	public void setMoney(double money) {
    		this.money = money;
    	}
    	public int getVersion() {
    		return version;
    	}
    	public void setVersion(int version) {
    		this.version = version;
    	}
    }

##### 配置映射 #####

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
    	<class name="com.dwx.models.Accounts" table="accounts">
    		<id name="id">
    			<generator class="native"></generator>
    		</id>
    		<version name="version"></version>
    		<property name="username"></property>	
    		<property name="money"></property>		
    	</class>
    </hibernate-mapping>

##### 创建测试类 #####

package com.dwx.models;
    import org.hibernate.Query;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    public class Test {
    	public static void main(String[] args) {
    		Session session=null;
    		Transaction tx=null;
    		try{
    			session=HibernateSessionFactory.getSession();
    			tx=session.beginTransaction();
    			Accounts a=(Accounts)session.load(Accounts.class, 1);
    			a.setMoney(800);
    			session.update(a);
    			tx.commit();
    		}catch(Exception e){
    			e.printStackTrace();
    		}finally{
    			HibernateSessionFactory.closeSession();
    		}
    	}
    }

##### 运行结果： #####

![2018052917141250][]

![20180529171422759][]

[20180529171141492]: /images/20220523/57313587340943e88d2ba24670c84bf9.png
[2018052917141250]: /images/20220523/172bd2b7707d4329b99d27f8987f07a7.png
[20180529171422759]: /images/20220523/01c66a3184fe4c7f95d242cd05044a21.png