hibernate级联情况下以commit或者flush来进行级联提交

最新推荐文章于 2020-09-09 11:18:52 发布

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最新推荐文章于 2020-09-09 11:18:52 发布

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文章标签： hibernate comomit flush 级联提交

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本文介绍了一种使用Hibernate框架在不显式调用update或save的情况下更新数据库中对象集合的方法。通过加载Person和Event对象并修改其集合属性，Hibernate能自动检测到这些变化并进行更新。

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1.2.3. 使关联工作

Now we will bring some people and events together in a new method in EventManager:

    private void addPersonToEvent(Long personId, Long eventId) {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        Person aPerson = (Person) session.load(Person.class, personId);
        Event anEvent = (Event) session.load(Event.class, eventId);
        aPerson.getEvents().add(anEvent);

        session.getTransaction().commit();
    }

After loading a Person and an Event, simply modify the collection using the normal collection methods. There is no explicit call to update() or save(); Hibernate automatically detects that the collection has been modified and needs to be updated. This is called automatic dirty checking. You can also try it by modifying the name or the date property of any of your objects. As long as they are in persistent state, that is, bound to a particular Hibernate org.hibernate.Session, Hibernate monitors any changes and executes SQL in a write-behind fashion. The process of synchronizing the memory state with the database, usually only at the end of a unit of work, is called flushing. In our code, the unit of work ends with a commit, or rollback, of the database transaction.