Hibernate 悲观锁与乐观锁(2)

当两个不同的事务同时读取到一条数据并进行修改时，这个时候程序就会抛出org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)异常。 

这里同样有两种情况 

一种是两个不同的事务的情况 

@Test public void testTransation1(){ Session session1 = null; Session session2 = null; try{ session1 = HibernateUtil.getSession(); session2 = HibernateUtil.getSession(); Info info1= session1.load(Info.class, "p003"); Info info2 = session2.load(Info.class, "p003"); Transaction tx1 = session1.beginTransaction(); info1.setName("2222222"); tx1.commit(); Transaction tx2 = session2.beginTransaction(); info2.setName("11111111"); tx2.commit(); System.out.println("事务2提交"); }catch(Exception e){ e.printStackTrace(); }finally{ if(session1 != null){ session1.close(); } if(session2 != null){ session2.close(); } } }

事务2提交时发现version的值不一样，这个时候就会抛出org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)异常.

第二种情况是子事务的情况 

@Test public void testTransation2(){ Session session1 = null; Session session2 = null; try{ session1 = HibernateUtil.getSession(); session2 = HibernateUtil.getSession(); Info info1= session1.load(Info.class, "p003"); Info info2 = session2.load(Info.class, "p003"); Transaction tx1 = session1.beginTransaction(); Transaction tx2 = session2.beginTransaction(); info2.setName("11111111"); tx2.commit(); info1.setName("2222222"); tx1.commit(); }catch(Exception e){ e.printStackTrace(); }finally{ if(session1 != null){ session1.close(); } if(session2 != null){ session2.close(); } } }

解决办法

1、捕获StaleObjectStateException异常，提示数据过时已被修改，让用户重新提交

2、尽量从业务方面去减小事务块，事务块越大，由乐观锁引起的问题的概率就越大

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