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hibernate hibernate使用ehcache二级缓存实践  

2009-11-09 16:47:30|  分类: cache |  标签: |举报 |字号 订阅

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Hibernate使用EHCache二级缓存    
数据库结构:



create table teamEH (id varchar(32),teamname varchar(32));
create table studentEH (id varchar(32),name varchar(32),team_id varchar(32));
POJO:



package EHCache;

public class Student ...{
    private String id; //标识id
    private String name; //学生姓名
    private Team team;//班级




    public String getName() ...{
        return name;
    }

  

    public void setId(String id) ...{
        this.id = id;
    }

  

    public void setName(String stuName) ...{
        this.name = stuName;
    }

 

    public String getId() ...{
        return id;
    }

    public Student() ...{ //无参的构造函数
    }

  

    public Team getTeam() ...{
        return team;
    }

    public void setTeam(Team team) ...{
        this.team = team;
    }
}




package EHCache;

import java.util.HashSet;
import java.util.Set;


public class Team ...{
    private String id;
    private Set students;
    private String teamName;
    public String getId() ...{
        return id;
    }

    public void setId(String id) ...{
        this.id = id;
    }

    public String getTeamName() ...{
        return teamName;
    }

    public void setTeamName(String name) ...{
        this.teamName = name;
    }

    public Set getStudents() ...{
        return students;
    }

    public void setStudents(Set students) ...{
        this.students = students;
    }
}

Team.hbm.xml

其中[cache]标签表示对student集合缓存,但只缓存id,如果需要缓存student实例,则需要在student.hbm.xml中的
class标签中配置[cache]



[?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"]
[!--
    Mapping file autogenerated by MyEclipse - Hibernate Tools
--]
[hibernate-mapping package="EHCache" ]
    [class name="EHCache.Team" table="teamEH" lazy="false"]
       [id name="id" column="id"]
         [generator class="uuid.hex"][/generator]
       [/id]
       [property name="teamName" column="teamName"][/property]
      
       [set name="students"
            lazy="true"
            inverse="true"
            outer-join="false"
            batch-size="2"
            cascade="save-update"
           ]
           [!-- 对students集合缓存,但只是缓存student-id如果要对整个对象缓存,
                还需要在Student.hbm.xml的class标签中加入[cache]标签 --]
         [cache usage="read-write"/]
         [key column="team_id"][/key]
         [one-to-many class="EHCache.Student"/]
       [/set]
      [/class]
[/hibernate-mapping]



Student.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"]
[!--
    Mapping file autogenerated by MyEclipse - Hibernate Tools
--]
[hibernate-mapping package="EHCache" ]
  
    [class name="EHCache.Student" table="studentEH" lazy="false"]
       [cache usage="read-write"/]
       [id name="id" column="id" unsaved-value="null"]
         [generator class="uuid.hex"][/generator]
       [/id]

       [property name="name" column="name"][/property]
   
       [many-to-one name="team"
                    column="team_id"
                    outer-join="true"
                    cascade="save-update"
                    class="EHCache.Team"][/many-to-one]
      [/class]
[/hibernate-mapping]



Hibernate.cfg.xml

配置hibernate.cache.provider_class以启用EHCache

[?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="connection.username"]root[/property]
    [property name="connection.url"]
        jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312&useUnicode=true
    [/property]
    [property name="dialect"]
        org.hibernate.dialect.MySQLDialect
    [/property]
    [property name="myeclipse.connection.profile"]mysql[/property]
    [property name="connection.password"]1234[/property]
    [property name="connection.driver_class"]
        com.mysql.jdbc.Driver
    [/property]
    [property name="hibernate.dialect"]
        org.hibernate.dialect.MySQLDialect
    [/property]
    [property name="hibernate.show_sql"]true[/property]
    [property name="current_session_context_class"]thread[/property]

    [property name="hibernate.cache.provider_class"]
            org.hibernate.cache.EhCacheProvider
        [/property]
    [mapping resource="EHCache/Student.hbm.xml" /]
    [mapping resource="EHCache/Team.hbm.xml" /]

[/session-factory]

[/hibernate-configuration]
EHCache.xml(放在classpath下)



[ehcache]


    [diskStore path="c:\cache"/]  [!--缓存文件存放位置--]

    [defaultCache
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        /]

    [cache name="EHCache.Student"
        maxElementsInMemory="500"    [!---超过500实例,就将多出的部分放置缓存文件中-]
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        /] --]

    [!-- Place configuration for your caches following --]

[/ehcache]



测试代码(插入准备数据部分)



package EHCache;

import java.io.File;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class Test ...{


    public static void main(String[] args) ...{
        String filePath=System.getProperty("user.dir")+File.separator+"src/EHCache"+File.separator+"hibernate.cfg.xml";
        File file=new File(filePath);
        SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();
        Session session=sessionFactory.openSession();
        Transaction tx=session.beginTransaction();
       
//        Team team=new Team();
//        team.setTeamName("team1");
//       
//       
//        for(int i=0;i[1000;i++){
//            Student stu=new Student();
//            stu.setName("tom"+i);
//            stu.setTeam(team);
//            session.save(stu);
//        }
//        tx.commit();
//       

    }

}



测试成功后,运行以下代码



package EHCache;

import java.io.File;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class Test ...{


    public static void main(String[] args) ...{
        String filePath=System.getProperty("user.dir")+File.separator+"src/EHCache"+File.separator+"hibernate.cfg.xml";
        File file=new File(filePath);
        SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();
        Session session=sessionFactory.openSession();
        Transaction tx=session.beginTransaction();
       
   
        //模拟多用户访问数据
        Session session1=sessionFactory.openSession();
        Transaction tx1=session1.beginTransaction();
        List list=session1.createQuery("from Student").list();
        for(int i=0;i[list.size();i++)...{
            Student stu=(Student)list.get(i);
            System.out.println(stu.getName());
        }
        tx1.commit();
        session1.close();   
   
        Session session2=sessionFactory.openSession();
        Transaction tx2=session2.beginTransaction();
            //这个uuid从刚才插入的数据中复制一个student的id
        Student stu=(Student)session2.get(Student.class, "4028818316d184820116d184900e0001");
        System.out.println(stu.getName());
        tx2.commit();
        session2.close();
    }

}



结果如下:

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select student0_.id as id0_, student0_.name as name0_, student0_.team_id as team3_0_ from studentEH student0_
Hibernate: select team0_.id as id1_0_, team0_.teamName as teamName1_0_ from teamEH team0_ where team0_.id=?
tom0
tom1
tom2
tom3
tom4
tom5
tom6
tom7
tom8
tom9
tom10
........................................

tom974
tom975
tom976
tom977
tom978
tom998
tom999
Hibernate: select team0_.id as id1_0_, team0_.teamName as teamName1_0_ from teamEH team0_ where team0_.id=?
tom0



可以看到,第二次查询,已经不再访问数据库了,而且,查看c:\cache文件夹,也可以看到,数据已经缓存成功了
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