Hibernate中的二级缓存 EHCache
hibernate.cfg.xml
代码：
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>
<session-factory>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="connection.url">
jdbc:mysql://localhost:3307/users
</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="myeclipse.connection.profile">mysqlusers</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="current_session_context_class">thread</property>
<property name="cache.provider_class">
org.hibernate.cache.EhCacheProvider
</property>
<mapping resource="com/b510/examplex/Guestbook.hbm.xml" />
</session-factory>
</hibernate-configuration>
在src目录下面编写ehcache.xml
代码；
<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
<!-- 说明：maxElementsInMemory 设置 保存在内存中的缓存对象的最大数量
etemal 设置缓存中对象 是否永远不过期，如果值为true，超过设置被忽略，缓存对象永远不过期
timeToIdleSeconds 设置缓存中对象在他过期之前的最大空闲时间，单位为秒
timeToLiveSeconds 设置缓存中对象在他过期之前的最大生存时间 ，单位为秒
overflowToDisk 设置内存中的缓存对象达到maxElementsInMemory限制时，是否将缓存对象保存到硬盘中
-->
<diskStore path="java.io.tmpdir"/>
<defaultCache maxElementsInMemory="10000" eternal="false"
timeToIdleSeconds="120" timeToLiveSeconds="120"
overflowToDisk="true"/>
<cache name="com.b510.examplex.Guestbook" maxElementsInMemory="1000"
eternal="true" timeToIdleSeconds="300" timeToLiveSeconds="600"
overflowToDisk="true"/>
</ehcache>
Guestbook.hbm.xml
代码：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.b510.examplex.Guestbook" table="guestbook"
catalog="users" optimistic-lock="version">
<!-- EHCache二级缓存的策略：
只读缓存 （read-only）
读/写缓存 （read-write）
不严格的读/写缓存 (nonstrict-read-write)
事务缓存 (transactional) EHCache不支持事务缓存
-->
<!-- 应用EHCache二级缓存的策略 -->
<cache usage="read-only"/>
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="increment" />
</id>
<version name="version" column="version" access="field"></version>
<property name="name" type="java.lang.String">
<column name="name" length="200" />
</property>
<property name="email" type="java.lang.String">
<column name="email" length="50" />
</property>
<property name="phone" type="java.lang.String">
<column name="phone" length="20" />
</property>
<property name="title" type="java.lang.String">
<column name="title" length="200" />
</property>
<property name="content" type="java.lang.String">
<column name="content" length="1000" />
</property>
<property name="createdTime" type="java.util.Date">
<column name="created_time" length="10" />
</property>
</class>
</hibernate-mapping>
测试代码：
HIbernateTest.java
代码：
/**
*
*/
package com.b510.examplex;
import java.util.Iterator;
import org.hibernate.Query;
import org.hibernate.Session;
/**
*
* @author XHW
*
* @date 2011-7-15
*
*/
public class HibernateTest {
/**
* @param args
*/
public static void main(String[] args) {
new HibernateTest().getGuestbooks();
}
public void getGuestbooks(){
Session session=HibernateSessionFactoryUtil.getSessionFactory().openSession();
session.beginTransaction();
Query query=session.createQuery("from Guestbook");
Iterator it=query.iterate();
while(it.hasNext()){
Guestbook gb=(Guestbook)it.next();
System.out.println("name: "+gb.getName()+" Id:"+gb.getId());
}
query=session.createQuery("from Guestbook where id=2");
Guestbook gb=(Guestbook)query.uniqueResult();
System.out.println("name: "+gb.getName()+" Id:"+gb.getId());
session.getTransaction().commit();
}
}
运行效果：
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
select
guestbook0_.id as col_0_0_
from
users.guestbook guestbook0_
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: liuwei Id:1
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: Hongtenzone@foxmail.com Id:2
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: Hongten Id:3
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:4
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:5
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:6
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:7
Hibernate:
select
guestbook0_.id as id0_,
guestbook0_.version as version0_,
guestbook0_.name as name0_,
guestbook0_.email as email0_,
guestbook0_.phone as phone0_,
guestbook0_.title as title0_,
guestbook0_.content as content0_,
guestbook0_.created_time as created8_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=2
name: Hongtenzone@foxmail.com Id:2
测试代码二：
HibernateTest.java
代码：
/**
*
*/
package com.b510.examplex;
import java.util.Iterator;
import org.hibernate.Query;
import org.hibernate.Session;
/**
*
* @author XHW
*
* @date 2011-7-15
*
*/
public class HibernateTest {
/**
* @param args
*/
public static void main(String[] args) {
new HibernateTest().getGuestbooks();
}
public void getGuestbooks(){
Session session=HibernateSessionFactoryUtil.getSessionFactory().openSession();
session.beginTransaction();
Query query=session.createQuery("from Guestbook");
Iterator it=query.iterate();
while(it.hasNext()){
Guestbook gb=(Guestbook)it.next();
System.out.println("name: "+gb.getName()+" Id:"+gb.getId());
}
Guestbook gb=(Guestbook)session.load(Guestbook.class, 2);
System.out.println("name: "+gb.getName()+" Id:"+gb.getId());
session.getTransaction().commit();
}
}
运行效果：
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate:
select
guestbook0_.id as col_0_0_
from
users.guestbook guestbook0_
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: liuwei Id:1
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: Hongtenzone@foxmail.com Id:2
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: Hongten Id:3
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:4
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:5
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:6
Hibernate:
select
guestbook0_.id as id0_0_,
guestbook0_.version as version0_0_,
guestbook0_.name as name0_0_,
guestbook0_.email as email0_0_,
guestbook0_.phone as phone0_0_,
guestbook0_.title as title0_0_,
guestbook0_.content as content0_0_,
guestbook0_.created_time as created8_0_0_
from
users.guestbook guestbook0_
where
guestbook0_.id=?
name: HOngten Id:7
name: Hongtenzone@foxmail.com Id:2
我们会看到这里和上面的查询结果不同的是，这次要少用一条select语句。这就是利用hibernate的二级缓存，
他在内存中保留了我们要查询的id=2的这条记录，所以当我们再次查询的时候，是直接从缓存中读出来。
