hibernate缓存

    public void query(int id){  //查
        Transaction transaction=session.beginTransaction();
        try{
            Student s=(Student)session.get(Student.class, id);//使用get()
            //session.evict(s);//1 清除缓存中的特定对象
            //session.clear();//2 清除缓存内容
            Student s1=(Student)session.get(Student.class, id);
            //Student s=session.load(Student.class, id);
            //Student s1=session.load(Student.class, id);
            System.out.println("s.id:"+s.getId());
            System.out.println("s.name:"+s.getName());
            System.out.println("s.description:"+s.getDescription());
            System.out.println("s1.id:"+s1.getId());
            System.out.println("s1.name:"+s1.getName());
            System.out.println("s1.description:"+s1.getDescription());
            transaction.commit();
        }catch(Exception e){
            System.out.println("查询数据失败");
            transaction.rollback();
        }    
public static void main(String[] args){
  TestHibernate ts=new TestHibernate();
  ts.query(1);
}    

   <property name="hibernate.cache.use_second_level_cache">true</property><!-- 开启二级缓存 -->
        
   <property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property><!-- 指定插件供应 -->

<!-- *.hbm.xml -->
<?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>
       <!-- 设置该持久化类的二级缓存并发访问策略 read-only read-write nonstrict-read-write transactional-->
       <cache usage="read-write"/>    
   </class>
</hibernate-mapping>

<hibernate-mapping>
        <class name="com.suxiaolei.hibernate.pojos.Customer" table="customer">
            <!-- 主键设置 -->
            <id name="id" type="string">
                <column name="id"></column>
                <generator class="uuid"></generator>
            </id>
            
            <!-- 属性设置 -->
            <property name="username" column="username" type="string"></property>
            <property name="balance" column="balance" type="integer"></property>
            
            <set name="orders" inverse="true" cascade="all" lazy="false" fetch="join">
                <cache usage="read-only"/>
                <key column="customer_id" ></key>
                <one-to-many class="com.suxiaolei.hibernate.pojos.Order"/>
            </set>
            
        </class>
    </hibernate-mapping>

<!-- ehcache.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
    <!--
        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="200" eternal="false" 
        timeToIdleSeconds="50" timeToLiveSeconds="60" overflowToDisk="true"></defaultCache>
    <!--
        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="com.suxiaolei.hibernate.pojos.Order" maxElementsInMemory="200" eternal="false" 
        timeToIdleSeconds="50" timeToLiveSeconds="60" overflowToDisk="true"></cache>
</ehcache>

package com.hibernate.manager;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.engine.HibernateIterator;

import com.hibernate.bean.Student;
import com.util.HibernateUtil;

public class SecendCache {
    private static final ThreadLocal<Session> threadLocal=new ThreadLocal<Session>();
    static SessionFactory sessionFactory=HibernateUtil.getSessionFactory();
    public static void main(String[] args){
        Session session=null;
        Session session2=null;
        session=getSession();
        session2=getSession();
        
        Student s=new Student();
        s.setId(3);
        s.setName("小明");
        s.setDescription("一个顽皮的孩子");
        session.beginTransaction();
        try{
            session.save(s);
            session.getTransaction().commit();
        }catch(Exception e){
            session.getTransaction().rollback();
        }
        session.clear();
        Student s1=session.get(Student.class, 3);
        System.out.println("第一个Session装载对象");
        Student s2=session2.get(Student.class, 3);
        System.out.println("第二个Session装载对象");
    }
    public static Session getSession(){
        Session session=(Session)threadLocal.get();
        session=(session==null)?sessionFactory.openSession():session;
        return session;        
    }

}