Hibernate二级缓存 - 入门示范(转)

一. 我们使用oscache来演示 , 引入oscache的jar包到工程中.

?

二. 把下载的Hibernate压缩包中的? hibernate-3.2\etc\oscache.properties放入classpath中. 用默认设置就行了.

?

三.修改hibernate.cfg.xml? , 加入如下, 意思启用二级缓存, 指定使用OSCache这个实现.

?

?

Xml代码 ?

1. <!DOCTYPE?hibernate-configuration?PUBLIC ??
2. ????"-//Hibernate/Hibernate?Configuration?DTD?3.0//EN" ??
3. ????"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">??
4. ??
5. <hibernate-configuration>??
6. ????<session-factory?>??
7. ????????<property?name="show_sql">true</property>??
8. ????????<property?name="hibernate.hbm2ddl.auto">update</property>??
9. ???????? ??
10. ????????<property?name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>??
11. ????????<property?name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>??
12. ????????????????? ??
13. ????????<property?name="hibernate.connection.url">jdbc:mysql:///test</property>??
14. ????????<property?name="hibernate.connection.username">root</property>??
15. ????????<property?name="hibernate.connection.password">1234</property>??
16. ???????? ??
17. ????????<!--?这行不写也行,默认就为true-->??
18. ????????<property?name="cache.use_second_level_cache">true</property>??
19. ????????<!--?对Query也开启缓存?,由于命中率太低,建议不开?-->??
20. ????????<property?name="cache.use_query_cache">true</property>??
21. ????????<!--?指定使用OSCache这个实现-->??
22. ????????<property?name="cache.provider_class">org.hibernate.cache.OSCacheProvider</property>??
23. ????????<!--?打开统计信息-->??
24. ????????<property?name="generate_statistics">true</property>???????? ??
25. ???????????? ??
26. ????????<mapping?resource="dao/po/Department.hbm.xml"/>??
27. ????????<mapping?resource="dao/po/Employee.hbm.xml"/>??
28. ????????<mapping?resource="dao/po/Person.hbm.xml"/>??
29. ????????<mapping?resource="dao/po/IdCard.hbm.xml"/>??
30. ????????<mapping?resource="dao/po/Teacher.hbm.xml"/>??
31. ????????<mapping?resource="dao/po/Student.hbm.xml"/>??
32. ????????<mapping?resource="dao/po/User.hbm.xml"/>? ??
33. ????????<mapping?resource="extends_test/extends_1/Person.hbm.xml"/>??
34. ????????<mapping?resource="extends_test/extends_2/Person.hbm.xml"/>??
35. ????????<mapping?resource="extends_test/extends_4/Person.hbm.xml"/>??? ??
36. ???? ??
37. ????????<!--?以下类被缓存-->??
38. ????????<class-cache?class="dao.po.Person"?usage="read-write"/>??
39. ???????? ??
40. ????</session-factory>??
41. </hibernate-configuration>??

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory >
		<property name="show_sql">true</property>
		<property name="hibernate.hbm2ddl.auto">update</property>
		
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
				 
		<property name="hibernate.connection.url">jdbc:mysql:///test</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">1234</property>
		
		<!-- 这行不写也行,默认就为true-->
		<property name="cache.use_second_level_cache">true</property>
		<!-- 对Query也开启缓存 ,由于命中率太低,建议不开 -->
		<property name="cache.use_query_cache">true</property>
		<!-- 指定使用OSCache这个实现-->
		<property name="cache.provider_class">org.hibernate.cache.OSCacheProvider</property>
		<!-- 打开统计信息-->
		<property name="generate_statistics">true</property>		
	    	
		<mapping resource="dao/po/Department.hbm.xml"/>
		<mapping resource="dao/po/Employee.hbm.xml"/>
		<mapping resource="dao/po/Person.hbm.xml"/>
		<mapping resource="dao/po/IdCard.hbm.xml"/>
		<mapping resource="dao/po/Teacher.hbm.xml"/>
		<mapping resource="dao/po/Student.hbm.xml"/>
		<mapping resource="dao/po/User.hbm.xml"/>	
		<mapping resource="extends_test/extends_1/Person.hbm.xml"/>
		<mapping resource="extends_test/extends_2/Person.hbm.xml"/>
		<mapping resource="extends_test/extends_4/Person.hbm.xml"/>	
	
		<!-- 以下类被缓存-->
		<class-cache class="dao.po.Person" usage="read-write"/>
		
	</session-factory>
</hibernate-configuration>

??

?

?

?

四.usage的说明

?

????? "read-only"????????????????????? 只读的,? po不能修改, 修改会抛异常

????? "read-write"??????????????????? 可对PO读写. 不怕并发修改

????? "nonstrict-read-write"???? 非严格的 读写, 并发修改不会问题,? 一般用在能容忍出问题的环境.

????? "transactional"??????????????? 有事务的,缓存 , oscache不是支持,? jboss 有实现.

?

?

?

五. 查询测试, 看看命中几次

?

Java代码 ?

1. package?cache_test; ??
2. ??
3. import?org.hibernate.Session; ??
4. import?org.hibernate.SessionFactory; ??
5. import?org.hibernate.stat.Statistics; ??
6. ??
7. import?dao.HibernateUtil; ??
8. import?dao.po.Person; ??
9. ??
10. /** ?
11. ?*?测试缓存 ?
12. ?*? ?
13. ?*/??
14. public?class?Test ??
15. { ??
16. ????public?static?void?main(final?String[]?args) ??
17. ????{ ??
18. ????????query(); ??
19. ????????final?SessionFactory?sf?=?HibernateUtil.getSessionFactory(); ??
20. ????????final?Statistics?s?=?sf.getStatistics(); ??
21. ????????System.out.println(s);?//打印所有信息?监测SessionFactory ??
22. ????????System.out.println("---------------"); ??
23. ????????System.out.println("放入:"?+?s.getSecondLevelCachePutCount());?//打印缓存的信息 ??
24. ????????System.out.println("命中:"?+?s.getSecondLevelCacheHitCount()); ??
25. ????????System.out.println("丢失:"?+?s.getSecondLevelCacheMissCount()); ??
26. ????} ??
27. ??
28. ????public?static?void?query() ??
29. ????{ ??
30. ????????Session?session?=?null; ??
31. ??
32. ????????for?(int?i?=?0;?i?<?10;?i++) ??
33. ????????{ ??
34. ????????????session?=?HibernateUtil.getSeesion(); ??
35. ????????????final?Person?p1?=?(Person)?session.get(Person.class,?1); ??
36. ????????????session.close(); ??
37. ????????????System.out.println(p1.getName()); ??
38. ????????} ??
39. ??
40. ????} ??
41. }??

package cache_test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.stat.Statistics;

import dao.HibernateUtil;
import dao.po.Person;

/**
 * 测试缓存
 * 
 */
public class Test
{
	public static void main(final String[] args)
	{
		query();
		final SessionFactory sf = HibernateUtil.getSessionFactory();
		final Statistics s = sf.getStatistics();
		System.out.println(s); //打印所有信息 监测SessionFactory
		System.out.println("---------------");
		System.out.println("放入:" + s.getSecondLevelCachePutCount()); //打印缓存的信息
		System.out.println("命中:" + s.getSecondLevelCacheHitCount());
		System.out.println("丢失:" + s.getSecondLevelCacheMissCount());
	}

	public static void query()
	{
		Session session = null;

		for (int i = 0; i < 10; i++)
		{
			session = HibernateUtil.getSeesion();
			final Person p1 = (Person) session.get(Person.class, 1);
			session.close();
			System.out.println(p1.getName());
		}

	}
}

?

?

六:? 打印出:

放入:1
命中:9
丢失:1