二级缓存的配置及实例详解

最新推荐文章于 2022-09-07 09:42:29 发布

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最新推荐文章于 2022-09-07 09:42:29 发布

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文章标签： hibernate session query iterator email class

本文链接：https://blog.youkuaiyun.com/Java958199586/article/details/7106150

本文详细介绍了Hibernate二级缓存的配置步骤，包括引入oscache库、开启二级缓存、指定缓存类。并通过实例展示了从二级缓存读取数据、使用Iterator检索、查询缓存、更新操作对缓存的影响，深入理解二级缓存的工作机制。

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二级缓存的配置及实例详解

1. 拷贝oscache-2.1.jar到当前工程的lib目录下

2. 开启二级缓存

<property

name="hibernate.cache.provider_class">org.hibernate.cache.OSCacheProvider</property>

3. 指定使用二级缓存的类

方法一:在映射文件中编写代码：<class name="Customers" table="Customers">

方法二:在配置文件中编写代码：<class-cache usage="read-write" class="cn.csdn.producets.domain.Customers"/>

<class-cache usage="read-write" class="cn.csdn.producets.domain.Orders" />

5.在src下添加一个文件oscache.xml

案例讲解：

一，从二级缓存中读取数据

@Test

public void testCache() {

// 丛二级缓存中读取数据

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Customers customer = (Customers) session.load(Customers.class, 3);

System.out.println(customer.getPass());

tx.commit();

session.close();

session = HibernateUtil.getSession();

tx = session.beginTransaction();

customer = (Customers) session.load(Customers.class, 3);

System.out.println(customer.getPass());

tx.commit();

session.close();

}

运行结果：Hibernate: select customers0_.id as id0_0_,customers0_.realName as realName0_0_, customers0_.pass as pass0_0_,customers0_.sex as sex0_0_, customers0_.petName as petName0_0_,customers0_.email as email0_0_, customers0_.rdate as rdate0_0_ from Customerscustomers0_ where customers0_.id=?

111

二．Iterator检索

public void testIterator(){

// iterator先到数据库中检索符合条件的id，然后根据id分别到一级缓存和二级缓存中查找对象，

// 因为第一次关闭了session，所以一级缓存里的数据已经不存在，而二级缓存中的3数据并没有消失。

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Query query = session.createQuery("from Orders o where o.id<11");

query.list().size();

tx.commit();

session.close();

session = HibernateUtil.getSession();

tx = session.beginTransaction();

query = session.createQuery("from Orders o");

Iterator<Orders> it = query.iterate();

while (it.hasNext()) {

System.out.println(it.next().getNumber());

}

tx.commit();

session.close();

}

运行结果：Hibernate: select orders0_.id as id1_, orders0_.number as number1_,orders0_.address as address1_, orders0_.phone as phone1_, orders0_.odate asodate1_, orders0_.sum as sum1_, orders0_.status as status1_, orders0_.cid ascid1_ from orders orders0_ where orders0_.id<11

Hibernate: select orders0_.idas col_0_0_ from orders orders0_

123

Hibernate: select orders0_.idas id1_0_, orders0_.number as number1_0_, orders0_.address as address1_0_,orders0_.phone as phone1_0_, orders0_.odate as odate1_0_, orders0_.sum assum1_0_, orders0_.status as status1_0_, orders0_.cid as cid1_0_ from ordersorders0_ where orders0_.id=?

123

三．查询缓存

public void testowerFlow(){

// 测试缓存溢出存放到临时目录

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Query query = session.createQuery("from Orders o");

query.list().size();

tx.commit();

session.close();

}

四．查询缓存

public void testQueryCache(){

// 查询缓存：查询缓存依赖二级缓存，所以必须开启二级缓存，查询缓存才起作用

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Query query = session

.createQuery("selectc.id from Customers c where c.pass='444'");

// 设置缓存，如果查询缓存存在，直接返回，如果查询缓存不存在，查询数据库，将查询结果设置到查询缓存中

query.setCacheable(true);

query.list();

System.out.println("--------");

tx.commit();

session.close();

session = HibernateUtil.getSession();

tx = session.beginTransaction();

query = session

.createQuery("selectc.id from Customers c where c.pass='444'");

query.setCacheable(true);

query.list();

System.out.println("--------");

tx.commit();

session.close();

}

运行结果：Hibernate: select customers0_.id as col_0_0_ from Customers customers0_where customers0_.pass='444'

--------

Hibernate: select customers0_.id as col_0_0_ from Customers customers0_where customers0_.pass='444'

五．

public void testUpdate(){

// 测试对对象的操作，会同步到二级缓存中。

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Customers customer = (Customers) session.load(Customers.class, 4);

System.out.println(customer.getPass());

customer.setPass("222");

tx.commit();

session.close();

session = HibernateUtil.getSession();

tx = session.beginTransaction();

customer = (Customers) session.load(Customers.class, 4);

System.out.println(customer.getPass());

tx.commit();

session.close();

}

Hibernate: selectcustomers0_.id as id0_0_, customers0_.realName as realName0_0_,customers0_.pass as pass0_0_, customers0_.sex as sex0_0_, customers0_.petNameas petName0_0_, customers0_.email as email0_0_, customers0_.rdate as rdate0_0_from Customers customers0_ where customers0_.id=?

444

Hibernate: update Customers setrealName=?, pass=?, sex=?, petName=?, email=?, rdate=? where id=?

222

六．

public void testUpdeatTim(){

// 改变值的时候同步到二级缓存中

// 当改变值得时候二级缓存会重新加载数据，以保证数据的一致性

Session session = HibernateUtil.getSession();

Transaction tx = session.beginTransaction();

Customers customer = (Customers) session.load(Customers.class, 4);

System.out.println(customer.getPass());

Query query = session

.createQuery("updateCustomers c set c.pass='444' where c.id=4");

query.executeUpdate();

tx.commit();

session.close();

session = HibernateUtil.getSession();

tx = session.beginTransaction();

customer = (Customers) session.load(Customers.class, 4);

System.out.println(customer.getPass());

tx.commit();

session.close();

}

运行结果：Hibernate: select customers0_.id as id0_0_, customers0_.realName asrealName0_0_, customers0_.pass as pass0_0_, customers0_.sex as sex0_0_,customers0_.petName as petName0_0_, customers0_.email as email0_0_,customers0_.rdate as rdate0_0_ from Customers customers0_ wherecustomers0_.id=?

222

Hibernate: update Customers setpass='444' where id=4

Hibernate: selectcustomers0_.id as id0_0_, customers0_.realName as realName0_0_, customers0_.passas pass0_0_, customers0_.sex as sex0_0_, customers0_.petName as petName0_0_,customers0_.email as email0_0_, customers0_.rdate as rdate0_0_ from Customerscustomers0_ where customers0_.id=?

444