悲观锁 HibernateTest.java

HibernateTest.java

代码：

/**
 *
 */
package com.b510.examplex;

import java.util.List;

import org.hibernate.LockMode;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

/**
 *
 * @author XHW
 *
 * @date 2011-7-8
 *
 */
public class HibernateTest {

 /**
  * @param args
  */
 public static void main(String[] args) {
  HibernateTest test = new HibernateTest();
  test.testLockMode();
 }

 public void testLockMode() {
  Session session = HibernateSessionFactoryUtil.getSessionFactory()
    .openSession();
  session.beginTransaction();
  
  Query query=session.createQuery("from Guestbook gb");
  //设置为“悲观锁”   悲观地认为每次读读取或修改数据库数据时，其他的事务也在并发访问相同的数据          <具有很强的排他性>
  query.setLockMode("gb", LockMode.UPGRADE);
  List<Guestbook> list=query.list();
  session.getTransaction().commit();
  
  for(Guestbook gb:list){
   System.out.println(gb.getId());
   System.out.println(gb.getName());
   System.out.println(gb.getTitle());
   System.out.println(gb.getEmail());
  }
  
 }

}

运行效果：

没有加“悲观锁”的效果：

sql语句：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: 
    select
        guestbook0_.id as id2_,
        guestbook0_.name as name2_,
        guestbook0_.email as email2_,
        guestbook0_.phone as phone2_,
        guestbook0_.title as title2_,
        guestbook0_.content as content2_,
        guestbook0_.created_time as created7_2_
    from
        users.guestbook guestbook0_
1
Hongten
hello world!
hongtenzone@foxmail.com

现在加入“悲观锁”

sql语句：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
    select
        guestbook0_.id as id2_,
        guestbook0_.name as name2_,
        guestbook0_.email as email2_,
        guestbook0_.phone as phone2_,
        guestbook0_.title as title2_,
        guestbook0_.content as content2_,
        guestbook0_.created_time as created7_2_
    from
        users.guestbook guestbook0_ for update
           
1
Hongten
hello world!
hongtenzone@foxmail.com