hibernate4 二级缓存demo实例

hibernate使用版本是：hibernate-release-4.2.5.Final

需要的jar包：hibernate-release-4.2.5.Final\lib\required下所有jar包

ehcache jar包：hibernate-release-4.2.5.Final\lib\optional\ehcache下所有包

junit：junit-4.10.jar和mysql-connector-java-5.1.15-bin.jar

注：hibernate 4.2.5版本ehcache缓存不依赖commons-logging-1.1.1.jar,需要的是slf4j-api-1.6.1.jar

项目结构如下



HibernateUtil

package com.action;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateUtil {

private static SessionFactory sessionFactory;

/**
* @return 获取会话工厂
*/
public static SessionFactory getSessionFactory(){

//第一步:读取Hibernate的配置文件  hibernamte.cfg.xml文件
Configuration con=new Configuration().configure();

//第二步:创建服务注册构建器对象，通过配置对象中加载所有的配置信息
ServiceRegistryBuilder regbulider=new ServiceRegistryBuilder().applySettings(con.getProperties());

//创建注册服务
ServiceRegistry reg=regbulider.buildServiceRegistry();

//第三步:创建会话工厂
SessionFactory sessionFactory=con.buildSessionFactory(reg);

return sessionFactory;
}

/**
* @return 获取会话对象
*/
public static Session getCurrentSession(){

return getSessionFactory().openSession();
}

public static void closeSession() {
// TODO Auto-generated method stub
}

}

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://127.0.0.1:3306/HibernateCache</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>

<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>

<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>

<!-- Disable the second-level cache -->
<!--<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>
-->

<!-- 配置二级缓存 -->
<property name="hibernate.cache.use_second_level_cache">true</property>
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
<!-- hibernate3的二级缓存配置 -->
<!-- <property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property> -->

<!-- 开启查询缓存 -->
<property name="hibernate.cache.use_query_cache">true</property>

<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>

<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<mapping class="com.bean.User" />

</session-factory>

</hibernate-configuration>

注意：hibernate4和hibernate3配置不一样，hibernate4是

<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>

而hibernate3的配置是

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

（此处有一个疑问是：hibernate4的官方文档中，已经把class改了，但是属性名称没有改，还是hibernate.cache.provider_class，不是上面的hibernate.cache.region.factory_class，但是写成hibernate.cache.provider_class会报错误）

ehcache.xml

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
updateCheck="false">

<!-- 缓存到硬盘的路径  -->
<diskStore path="d:/ehcache"></diskStore>

<!--
默认设置
maxElementsInMemory : 在內存中最大緩存的对象数量。
eternal : 缓存的对象是否永远不变。
timeToIdleSeconds ：可以操作对象的时间。
timeToLiveSeconds ：缓存中对象的生命周期，时间到后查询数据会从数据库中读取。
overflowToDisk ：内存满了，是否要缓存到硬盘。
-->
<defaultCache maxElementsInMemory="1000" eternal="false"
timeToIdleSeconds="120" timeToLiveSeconds="120" overflowToDisk="true" />

<!--
指定缓存的对象。
下面出现的的属性覆盖上面出现的，没出现的继承上面的。
-->
<cache name="userCache" eternal="false" maxElementsInMemory="1000"
overflowToDisk="false" diskPersistent="false" timeToIdleSeconds="3600"
timeToLiveSeconds="3600" memoryStoreEvictionPolicy="LFU" />

</ehcache>

User实体类

package com.bean;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;

@Entity
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class User{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

UserTest测试类（JUnit）：

package com.test;

import org.hibernate.Session;
import org.junit.Test;

import com.action.HibernateUtil2;
import com.bean.User;

public class UserTest {

@Test
public void testEhcache() {
Session session = HibernateUtil.getCurrentSession();
session.beginTransaction();
User u1 = (User) session.load(User.class, 3);
System.out.println(u1.getName());
session.getTransaction().commit();
session.close();
Session session2 = HibernateUtil.getSessionFactory().openSession();

session2.beginTransaction();
User u2 = (User) session2.load(User.class, 3);
System.out.println(u2.getName());
session2.getTransaction().commit();
session2.close();
}

}

结果：

Hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.name as name3_0_0_ from User user0_ where user0_.id=?
zhangsan
zhangsan