Hibernate 中的attachDirty,attachClean,merge,findByProperty和findByExample

来源：互联网发布：js 扩展window对象编辑：程序博客网时间：2024/06/05 01:10

本文地址：http://blog.csdn.net/shanglianlm/article/details/51209825

attachDirty：将传入的对象持久化并保存。如果对象未保存（Transient状态），调用save方法保存。如果对象已保存（Detached状态），调用update方法将对象与Session重新关联。

public void attachDirty(Addressbook instance) {        log.debug("attaching dirty Addressbook instance");        try {            getHibernateTemplate().saveOrUpdate(instance);            log.debug("attach successful");        } catch (RuntimeException re) {            log.error("attach failed", re);            throw re;        }    }

attachClean：将传入的对象状态设置为Transient状态。

    public void attachClean(Addressbook instance) {        log.debug("attaching clean Addressbook instance");        try {            getHibernateTemplate().lock(instance, LockMode.NONE);            log.debug("attach successful");        } catch (RuntimeException re) {            log.error("attach failed", re);            throw re;        }    }

merge：将传入的detached状态的对象的属性复制到持久化对象中，并返回该持久化对象。如果该session中没有关联的持久化对象，加载一个，如果传入对象未保存，保存一个副本并作为持久对象返回，传入对象依然保持detached状态。

public Addressbook merge(Addressbook detachedInstance) {        log.debug("merging Addressbook instance");        try {            Addressbook result = (Addressbook) getHibernateTemplate().merge(                    detachedInstance);            log.debug("merge successful");            return result;        } catch (RuntimeException re) {            log.error("merge failed", re);            throw re;        }    }

findByProperty： propertyName指向列明，value对应的值，这样写便于对该表不同字段查询合用一个方法，查询时传入要查的列名和对应的值就可以了，例如HQL查询商品信息的语句如下：
String querysql = “from GoodsInfo as u where u.”+propertyName+” like ‘%”+value+”%’ order by u.goods_price asc”

public List findByProperty(String propertyName, Object value) {        log.debug("finding Addressbook instance with property: " + propertyName                + ", value: " + value);        try {            String queryString = "from Addressbook as model where model."                    + propertyName + "= ?";            return getHibernateTemplate().find(queryString, value);        } catch (RuntimeException re) {            log.error("find by property name failed", re);            throw re;        }    }

findByExample：

public List findByExample(Addressbook instance) {        log.debug("finding Addressbook instance by example");        try {            List results = getHibernateTemplate().findByExample(instance);            log.debug("find by example successful, result size: "                    + results.size());            return results;        } catch (RuntimeException re) {            log.error("find by example failed", re);            throw re;        }    }

0 0