Session(默认启动)一级缓存
SessionFactory(默认关闭)二级缓存
二级缓存速度快
一旦在应用中开启了SessionFactory二级缓存,那么Session默认使用二级缓存
开启二级缓存要在hibernate.cfg.xml中添加:
<!-- 开启二级缓存缓存 -->
<property name="hibernate.cache.use_query_cache">true</property>
<!-- 设置二级缓存的实现类-->
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
将缓存实现所需的配置文件添加到类加载路径中,对于EHCashe缓存,它需要一个ehcacha.xml配置文件:
<?xml version="1.0" encoding="GBK"?> <ehcache> <diskStore path="java.io.tmpdir"/> <defaultCache maxElementsInMemory="10000" eternal="false" timeToIdleSeconds="120" timeToLiveSeconds="120" overflowToDisk="true" diskPersistent="false" /> </ehcache>
示例类及类的配置文件:
package com.pengsuen.bean; public class News { private int id; private String title; private String conment; public News(){} public News(String title,String conment){ this.title=title; this.conment=conment; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getConment() { return conment; } public void setConment(String conment) { this.conment = conment; } }
News.hbm.xml
<?xml version="1.0"?> <!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.pengsuen.bean.News" table="NEWS"> <cache usage="read-only"/> <id name="id" type="int"> <column name="ID" /> <generator class="increment" /> </id> <property name="title" type="java.lang.String"> <column name="title" /> </property> <property name="conment" type="java.lang.String"> <column name="conment" /> </property> </class> </hibernate-mapping>
主配置文件略
测试类:
package com.pengsuen.test; import java.util.List; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import com.pengsuen.bean.News; public class Test { public static void main(String[] args) { // 默认找hibernate.cfg.xml Configuration conf = new Configuration().configure(); SessionFactory sf = conf.buildSessionFactory(); News news1= new News("success","ok"); News news2= new News("fuck","ko"); Session session0 = sf.openSession(); session0.beginTransaction(); session0.save(news1); session0.save(news2); List names = session0.createQuery("from News news").list(); session0.getTransaction().commit(); System.out.println("-------------------------"); Session session2 = sf.openSession(); session2.beginTransaction(); News user = (News)session2.load(News.class, 2); System.out.println(user.getTitle() + " " + user.getConment()); session2.getTransaction().commit(); session0.close(); session2.close(); sf.close(); } }执行结果: