Question

我在hibernate.cfg.xml，ehcache.xml中使用 Ehcache 配置了二级缓存。并在映射文件中设置了cache-usage属性。并检查数据是从缓存加载还是db使用hibenrate statices.But它没有加载。它再次执行查询。我提到了代码

<hibernate-configuration>
<session-factory>
    <property name="connection.username">pension2</property>
    <property name="connection.password">pension2</property>
    <property name="connection.url">jdbc:oracle:thin:@191.161.0.25:1521:pension</property>
    <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
    <property name="dialect">org.hibernate.dialect.OracleDialect</property>
    <property name="myeclipse.connection.profile">pension</property>
    <property name="show_sql">true</property>
    <property name="format_sql">true</property>
    <property name="use_sql_comments">true</property>

    <property name="hibernate.cache.use_second_level_cache">true</property>
    <property name="hibernate.generate_statistics">true</property>
    <property name="hibernate.cache.region.provider_class">
         net.sf.ehcache.hibernate.EhCacheProvider</property>
    <property name="hibernate.cache.provider_configuration_file_resource_path">/ehcache.xml </property>      
    <mapping resource="com/aims/mapping/Teacher.hbm.xml" />
    <mapping resource="com/aims/mapping/Student.hbm.xml" />
    <mapping resource="com/aims/mapping/Student_marks_detl.hbm.xml" />
    <mapping resource="com/aims/mapping/User.hbm.xml" />

</session-factory>
</hibernate-configuration>

ehcache.xml中

    <ehcache> 
    <diskStore path="java.io.tmpdir"/> 
     <cache name="com.aims.beans.Teacher" 
    maxElementsInMemory="300" 
    eternal="false" 
    overflowToDisk="false"/> 
    </ehcache>

Mapping.xml

<hibernate-mapping>
<class name="com.aims.beans.Teacher" table="teacher">
<cache usage="read-write" />
<id name="tno" column="tno" type="java.lang.Integer" >
    <generator class="assigned" />
</id>
<property name="tname" type="java.lang.String" column="tname"/>
</class> 
</hibernate-mapping>

我尝试在jsp.So中加载教师列表，Iam使用createquery和setCacheable为真。

long oldHitCount = HibernateUtil.getHitCount（）;
  long oldMissCount = HibernateUtil.getMissCount（）;
  log.info（“oldHitCount”+ oldHitCount +“oldMissCount”+ oldMissCount）;   查询q = session.createQuery（“来自老师”）;   q.setCacheable（真）;
  list = q.list（）;   long newHitCount = HibernateUtil.getHitCount（）;
  long newMissCount = HibernateUtil.getMissCount（）;

HibernateUtil.getHitCount（）/ HibernateUtil.getMissCount（）代码

public static long getHitCount() {
        long hitcount = 0;
        hitcount = sessionFactory.getStatistics()
                .getSecondLevelCacheStatistics("com.aims.beans.Teacher")
                .getHitCount();
        return hitcount;
    }

    public static long getMissCount() {
        long miscount = 0;
        miscount = sessionFactory.getStatistics()
                .getSecondLevelCacheStatistics("com.aims.beans.Teacher")
                .getMissCount();
        return miscount;
    }

但每次执行createQuery.I配置以及为什么它没有从缓存中返回。是否有任何错误配置二级缓存。请帮助我＆gt;？

Answer 1

二级缓存将id映射到实体，因此仅在通过id查询实体时使用。查询缓存将查询映射到查询检索的一组实体ID。因此，二级缓存和查询缓存实际上只在一起使用时才有用。

要启用查询缓存，仅设置查询可缓存是不够的，但您还必须在Hibernate session-factory配置中启用查询缓存：

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

希望这有帮助。

配置的二级缓存和数据未从二级缓存加载

1 个答案: