hibernate中的optimistic-lock(...

注意：要在user表中增加一个字段：version int  
User.hbm.xml


"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">


optimistic-lock="version" >
   
     
     
   
   
   

   
     
   
   

   

     
     
   






OptimisticlLockingTest.java

package com.shiryu.otm;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Expression;

//乐观锁 Optimistic Lock
public class OptimisticLockingTest {
    public static void main(String[] args) {
        SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
        Session session = sessionFactory.openSession();
        Criteria criteria = session.createCriteria(User.class);
        criteria.add(Expression.eq("name", "zhaiyu"));

        List l = criteria.list();

        User user = (User) l.get(0);
        Transaction tr = session.beginTransaction();
        user.setAge(21);// 更新age字段
        tr.commit();
        session.close();
        // 每次对数据库进行更新时，数据库中version都在递增

        // 现在我们尝试在tr.commit之前，启动另外一个Session，对zhaiyu用户进行操作，模拟并发时的情景

        Session session1 = sessionFactory.openSession();
        Criteria criteria1 = session1.createCriteria(User.class);
        criteria1.add(Expression.eq("name", "zhaiyu"));

        Session session2 = sessionFactory.openSession();
        Criteria criteria2 = session2.createCriteria(User.class);
        criteria2.add(Expression.eq("name", "zhaiyu"));

        List userList1 = criteria1.list();
        List userList2 = criteria2.list();

        User user1 = (User) userList1.get(0);
        User user2 = (User) userList2.get(0);

        Transaction tr1 = session1.beginTransaction();
        Transaction tr2 = session2.beginTransaction();

        user1.setAge(26);// 更新age字段
        tr1.commit();

        user2.setAge(44);// 更新age字段
        tr2.commit();// 系统出现StaleObjectStateException异常，并指出版本检测失败
    }
}