hibernate二级缓存配置

hibernate二级缓存配置

 

 

ehcache.xml：

<ehcache>

    <!-- Sets the path to the directory where cache .data files are created.

         If the path is a Java System Property it is replaced by
         its value in the running VM.

         The following properties are translated:
         user.home - User's home directory
         user.dir - User's current working directory
         java.io.tmpdir - Default temp file path -->
    <diskStore path="java.io.tmpdir"/>


    <!--Default Cache configuration. These will applied to caches programmatically created through
        the CacheManager.

        The following attributes are required for defaultCache:

        maxInMemory       - Sets the maximum number of objects that will be created in memory
        eternal           - Sets whether elements are eternal. If eternal,  timeouts are ignored and the element
                            is never expired.
        timeToIdleSeconds - Sets the time to idle for an element before it expires. Is only used
                            if the element is not eternal. Idle time is now - last accessed time
        timeToLiveSeconds - Sets the time to live for an element before it expires. Is only used
                            if the element is not eternal. TTL is now - creation time
        overflowToDisk    - Sets whether elements can overflow to disk when the in-memory cache
                            has reached the maxInMemory limit.

        -->
    <defaultCache
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        />

    <!--Predefined caches.  Add your cache configuration settings here.
        If you do not have a configuration for your cache a WARNING will be issued when the
        CacheManager starts

        The following attributes are required for defaultCache:

        name              - Sets the name of the cache. This is used to identify the cache. It must be unique.
        maxInMemory       - Sets the maximum number of objects that will be created in memory
        eternal           - Sets whether elements are eternal. If eternal,  timeouts are ignored and the element
                            is never expired.
        timeToIdleSeconds - Sets the time to idle for an element before it expires. Is only used
                            if the element is not eternal. Idle time is now - last accessed time
        timeToLiveSeconds - Sets the time to live for an element before it expires. Is only used
                            if the element is not eternal. TTL is now - creation time
        overflowToDisk    - Sets whether elements can overflow to disk when the in-memory cache
                            has reached the maxInMemory limit.

        -->

    <!-- Sample cache named sampleCache1
        This cache contains a maximum in memory of 10000 elements, and will expire
        an element if it is idle for more than 5 minutes and lives for more than
        10 minutes.

        If there are more than 10000 elements it will overflow to the
        disk cache, which in this configuration will go to wherever java.io.tmp is
        defined on your system. On a standard Linux system this will be /tmp"
        -->
    <cache name="sampleCache1"
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="300"
        timeToLiveSeconds="600"
        overflowToDisk="true"
        />

    <!-- Sample cache named sampleCache2
        This cache contains 1000 elements. Elements will always be held in memory.
        They are not expired. -->
    <cache name="sampleCache2"
        maxElementsInMemory="1000"
        eternal="true"
        timeToIdleSeconds="0"
        timeToLiveSeconds="0"
        overflowToDisk="false"
        /> -->

    <!-- Place configuration for your caches following -->

</ehcache>

 

使用cache查询：

1、java类：
/**
     * 功能:
     * 开启一个session
     * 开启查询缓存 关闭二级缓存
     * 使用query接口的iterator方法
     * 查询部分属性
     */
    @Test
    public void testQuery_cache04() {
        Session session = null;
        Transaction tx = null;
        try {
            session = HibernateUtils.getSession();
            Query query=session.createQuery("select c.name from Customers c");
            //开启查询缓存
            query.setCacheable(true);
            for(Iterator it=query.iterate();it.hasNext();){
                String obj=(String)it.next();
                System.out.println(obj);
            }
            ///////////////////////////////////////////////////////
            //查询缓存对query.iterator()方法没有影响
            query=session.createQuery("select c.name from Customers c");
            //开启查询缓存
            query.setCacheable(true);
            for(Iterator it=query.iterate();it.hasNext();){
                String obj=(String)it.next();
                System.out.println(obj);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            HibernateUtils.closeSession();
        }
    }
   
2、hibernate.cfg.xml配置：
<!-- 开启二级缓存 -->
    <property name="hibernate.cache.use_second_level_cache">true</property>
    <!-- 指定缓存提供商 -->
    <property name="hibernate.cache.provider_class">
        org.hibernate.cache.EhCacheProvider
    </property>
    <!-- 开启查询缓存 -->
    <property name="hibernate.cache.use_query_cache">true</property>
    <!-- 指定使用二级缓存的类 放在maping下面 -->
    <mapping resource="cn/java/query_cache/Customers.hbm.xml" />
    <mapping resource="cn/java/query_cache/Orders.hbm.xml" />
    <class-cache class="cn.java.query_cache.Customers"
        usage="read-only" />
       
3、ehcache.xml与hibernate.cfg.xml同级存放