Hibernate乐观锁实现之Timestamp

create?table?studentTimestamp(id?varchar(32),name?varchar(32),lastUpdateDateTime?timestamp?not?null?default?current_timestamp?on?update?current_timestamp);

?

pojos:

?

package?Timestamp;

import?java.util.Date;

public?class?Student?{
??private?String?id;
??private?String?name;
??private?Date?lastUpdateDateTime;
public?String?getId()?{
????return?id;
}
public?Date?getLastUpdateDateTime()?{
????return?lastUpdateDateTime;
}
public?void?setLastUpdateDateTime(Date?lastUpdateDateTime)?{
????this.lastUpdateDateTime?=?lastUpdateDateTime;
}
public?void?setId(String?id)?{
????this.id?=?id;
}
public?String?getName()?{
????return?name;
}
public?void?setName(String?name)?{
????this.name?=?name;
}



}

?Student.hbm.xml

?

<?xml?version="1.0"?encoding="utf-8"?>
<!DOCTYPE?hibernate-mapping?PUBLIC?"-//Hibernate/Hibernate?Mapping?DTD?3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--?
????Mapping?file?autogenerated?by?MyEclipse?-?Hibernate?Tools
-->
<hibernate-mapping>
<class?name="Timestamp.Student"?table="studentTimestamp"?>
????<id?name="id"?unsaved-value="null">
??????<generator?class="uuid.hex"></generator>
????</id>
????<!--?timestamp标签必须跟在id标签后面?-->
????<timestamp?name="lastUpdateDateTime"?column="lastUpdateDateTime"></timestamp>
????<property?name="name"?type="string"?column="name"></property>??
</class>

</hibernate-mapping>

?

Hibernate.cfg.xml

?

<?xml?version='1.0'?encoding='UTF-8'?>
<!DOCTYPE?hibernate-configuration?PUBLIC
??????????"-//Hibernate/Hibernate?Configuration?DTD?3.0//EN"
??????????"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!--?Generated?by?MyEclipse?Hibernate?Tools.???????????????????-->
<hibernate-configuration>

<session-factory>
????<property?name="connection.username">root</property>
????<property?name="connection.url">
????????jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312&useUnicode=true
????</property>
????<property?name="dialect">
????????org.hibernate.dialect.MySQLDialect
????</property>
????<property?name="myeclipse.connection.profile">mysql</property>
????<property?name="connection.password">1234</property>
????<property?name="connection.driver_class">
????????com.mysql.jdbc.Driver
????</property>
????<property?name="hibernate.dialect">
????????org.hibernate.dialect.MySQLDialect
????</property>
????<property?name="hibernate.show_sql">true</property>
????<property?name="current_session_context_class">thread</property>
????<property?name="jdbc.batch_size">15</property>
????<mapping?resource="Timestamp/Student.hbm.xml"?/>




</session-factory>

</hibernate-configuration>

?

测试代码：

?

package?Timestamp;


import?java.io.File;
import?java.util.Iterator;
import?java.util.Set;

import?org.hibernate.Session;
import?org.hibernate.SessionFactory;
import?org.hibernate.Transaction;
import?org.hibernate.cfg.Configuration;

public?class?Test?{


????public?static?void?main(String[]?args)?{

????????String?filePath=System.getProperty("user.dir")+File.separator+"src/Timestamp"+File.separator+"hibernate.cfg.xml";
????????File?file=new?File(filePath);
????????System.out.println(filePath);
????????SessionFactory?sessionFactory=new?Configuration().configure(file).buildSessionFactory();
????????Session?session=sessionFactory.openSession();
????????Transaction?t=session.beginTransaction();
????????
????????Student?stu=new?Student();
????????stu.setName("tom11");
????????session.save(stu);
????????t.commit();
??????
????????
????????/*
?????????*?模拟多个session操作student数据表
?????????*/
????????
????????Session?session1=sessionFactory.openSession();
????????Session?session2=sessionFactory.openSession();
????????Student?stu1=(Student)session1.createQuery("from?Student?s?where?s.name='tom11'").uniqueResult();
????????Student?stu2=(Student)session2.createQuery("from?Student?s?where?s.name='tom11'").uniqueResult();
????????
????????//这时候，两个版本号是相同的
????????System.out.println("v1="+stu1.getLastUpdateDateTime()+"--v2="+stu2.getLastUpdateDateTime());
????????
????????Transaction?tx1=session1.beginTransaction();
????????stu1.setName("session1");
????????tx1.commit();
????????//这时候，两个版本号是不同的，其中一个的版本号递增了
????????System.out.println("v1="+stu1.getLastUpdateDateTime()+"--v2="+stu2.getLastUpdateDateTime());
????????
????????Transaction?tx2=session2.beginTransaction();
????????stu2.setName("session2");
????????tx2.commit();
????????
????????
????????
????}

}

?

测试结果：

Hibernate: insert into studentTimestamp (lastUpdateDateTime, name, id) values (?, ?, ?)
Hibernate: select student0_.id as id0_, student0_.lastUpdateDateTime as lastUpda2_0_, student0_.name as name0_ from studentTimestamp student0_ where student0_.name='tom11'

Hibernate: select student0_.id as id0_, student0_.lastUpdateDateTime as lastUpda2_0_, student0_.name as name0_ from studentTimestamp student0_ where student0_.name='tom11'
v1=2007-12-12 16:30:53.0--v2=2007-12-12 16:30:53.0

Hibernate: update studentTimestamp set lastUpdateDateTime=?, name=? where id=? and lastUpdateDateTime=?

Exception in thread "main" org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect):?

v1=2007-12-12 16:30:54.844--v2=2007-12-12 16:30:53.0

Hibernate: update studentTimestamp set lastUpdateDateTime=?, name=? where id=? and lastUpdateDateTime=?