通过在表中及POJO中增加一个version字段来表示记录的版本，来达到多用户同时更改一条数据的冲突
数据库脚本：
create table studentVersion (id varchar(32),name varchar(32),ver int);
POJO
package Version;
public class Student {
private String id;
private String name;
private int version;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getVersion() {
return version;
}
public void setVersion(int version) {
this.version = version;
}
}
Student.hbm.xml
< xml version="1.0" encoding="utf-8" >
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
Hibernate.cfg.xml
< xml version='1.0' encoding='UTF-8' >
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
jdbc:mysql://localhost:3306/schoolproject characterEncoding=gb2312&useUnicode=true
org.hibernate.dialect.MySQLDialect
com.mysql.jdbc.Driver
org.hibernate.dialect.MySQLDialect
测试代码：
package Version;
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/Version"+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.getVersion()+"--v2="+stu2.getVersion());
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.getVersion()+"--v2="+stu2.getVersion());
Transaction tx2=session2.beginTransaction();
stu2.setName("session2");
tx2.commit();
}
}
运行结果：
Hibernate: insert into studentVersion (ver, name, id) values ( , , )
Hibernate: select student0_.id as id0_, student0_.ver as ver0_, student0_.name as name0_ from studentVersion student0_ where student0_.name='tom11'
Hibernate: select student0_.id as id0_, student0_.ver as ver0_, student0_.name as name0_ from studentVersion student0_ where student0_.n