hibernate查询缓存和二级缓存

最新推荐文章于 2025-07-28 23:27:29 发布

转载最新推荐文章于 2025-07-28 23:27:29 发布 · 517 阅读

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#hibernate #session #class #join #query #iterator

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本文详细介绍了Hibernate查询缓存的配置及使用方法，包括如何在配置文件中启用查询缓存，以及在程序中如何手动设置查询缓存。通过具体示例展示了查询缓存与二级缓存结合使用的效果。

hibernate查询缓存

查询缓存是针对普通属性结果集的缓存——个人推荐用这个，单独用查询缓存。
对实体对象的结果集只缓存id ，这配合hibernate二级缓存一起用.

查询缓存的生命周期，当前关联的表发生修改，那么查询缓存生命周期结束——推荐用来，查询那些不经常变更的数据，如数据字典。

查询缓存只对query.list()起作用，query.iterate不起作用，也就是query.iterate不使用

查询缓存的配置和使用：
* 在hibernate.cfg.xml文件中启用查询缓存，如：
<property name="hibernate.cache.use_query_cache">true</property> //默认是fasle
* 在程序中必须手动启用查询缓存，如：
query.setCacheable(true);

hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.url">
   jdbc:mysql://192.168.1.3:3306/hibernate
</property>
<property name="hibernate.connection.username">*****</property>
<property name="hibernate.connection.password">*****</property>
<property name="hibernate.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="hibernate.cache.use_second_level_cache">true</property>

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


<property name="hibernate.cache.use_query_cache">true</property>

<mapping resource="com/model/Classes.hbm.xml" />
<mapping resource="com/model/Student.hbm.xml" />


<class-cache class="com.model.Student" usage="read-only"/>
</session-factory>
</hibernate-configuration>

普通属性结果集测试用例：

public void testList3() {
   Session session = null;
   Transaction ta = null;
   try {
    session = HibernateUtil.getSession();
    ta = session.beginTransaction();
    Query query = session.createQuery("select name from Student");
   //开启查询缓存
    query.setCacheable(true);
    List stuList = query.list(); //发出sql
    for(Iterator it = stuList.iterator(); it.hasNext();){
     String stuName = (String)it.next();
     System.out.println(stuName);
    }
    ta.commit();
   } catch (Exception e) {
    e.printStackTrace();
    if (ta != null) {
     ta.rollback();
    }
   } finally {
    // 关闭session， user变为detached离线对象
    HibernateUtil.closeSession(session);
   }

   System.out.println("========第二次查询============");

   try {
    session = HibernateUtil.getSession();
    ta = session.beginTransaction();
    Query query = session.createQuery("select name from Student");
   //开启查询缓存
    query.setCacheable(true);
    List stuList = query.list(); // 不发出sql，查询缓存与session的生命周期无关
    for(Iterator it = stuList.iterator(); it.hasNext();){
     String stuName = (String)it.next();
     System.out.println(stuName);
    }
    ta.commit();
   } catch (Exception e) {
    e.printStackTrace();
    if (ta != null) {
     ta.rollback();
    }
   } finally {
    // 关闭session， user变为detached离线对象
    HibernateUtil.closeSession(session);
   }

}

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执行以下实体对象测试用例

public void testList() {
   Session session = null;
   Transaction ta = null;
   try {
    session = HibernateUtil.getSession();
    ta = session.beginTransaction();
    Query query= session.createQuery("from Student");
    query.setCacheable(true);//开启查询缓存
    List stuList = query.list();
    for(Iterator it = stuList.iterator(); it.hasNext();){
     Student stu = (Student)it.next();
     System.out.println(stu.getName());
    }
    ta.commit();
   } catch (Exception e) {
    e.printStackTrace();
    if (ta != null) {
     ta.rollback();
    }
   } finally {
    // 关闭session， user变为detached离线对象
    HibernateUtil.closeSession(session);
   }
   System.out.println("=============================");
   try {
    session = HibernateUtil.getSession();
    ta = session.beginTransaction();
    Query query= session.createQuery("from Student");
    query.setCacheable(true);//开启查询缓存
    List stuList = query.list();
    for(Iterator it = stuList.iterator(); it.hasNext();){
     Student stu = (Student)it.next();
     System.out.println(stu.getName());
    }
    ta.commit();
   } catch (Exception e) {
    e.printStackTrace();
    if (ta != null) {
     ta.rollback();
    }
   } finally {
    // 关闭session， user变为detached离线对象
    HibernateUtil.closeSession(session);
   }

}

1）hibernate 查询缓存true 与二级缓存fasle

<property name="hibernate.cache.use_second_level_cache">false</property>

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


<property name="hibernate.cache.use_query_cache">true</property>

<mapping resource="com/model/Classes.hbm.xml" />
<mapping resource="com/model/Student.hbm.xml" />


<class-cache class="com.zd.model.Student" usage="read-only"/>

输出结果：

13:59:43,589 WARN EhCacheProvider:86 - Could not find configuration [org.hibernate.cache.UpdateTimestampsCache]; using defaults.
13:59:43,620 WARN EhCacheProvider:86 - Could not find configuration [org.hibernate.cache.StandardQueryCache]; using defaults.
Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.class_id as class3_1_ from student_join student0_
学生1
学生2
学生3
学生4
学生5
学生6
学生7
学生8
=============================
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_, student0_.name as name1_0_, student0_.class_id as class3_1_0_ from student_join student0_ where student0_.id=?
学生1
学生2
学生3
学生4
学生5
学生6
学生7
学生8

分析：

//会发出n条查询语句，因为开启了查询缓存，关闭了二级缓存，那么查询缓存会缓存实体对象的id
//所以hibernate会根据实体对象的id去查询相应的实体，如果缓存中不存在相应的
//实体那么将发出根据实体id查询的sql语句，否则不会发出sql使用缓存中的数据

2）hibernate 查询缓存true 与二级缓存true

<property name="hibernate.cache.use_second_level_cache">true</property>

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


<property name="hibernate.cache.use_query_cache">true</property>

<mapping resource="com/model/Classes.hbm.xml" />
<mapping resource="com/model/Student.hbm.xml" />


<class-cache class="com.zd.model.Student" usage="read-only"/>

输出结果：