java – 无法做二级缓存

发布时间：2020-12-15 04:51:37 所属栏目：Java 来源：网络整理

导读：在我的applicationcontext.xml中 bean id="annotatedsessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"property name="packagesToScan" value="testonly.package.model" /property name="hibernatePrope

在我的applicationcontext.xml中

<bean id="annotatedsessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="packagesToScan" value="testonly.package.model" />
<property name="hibernateProperties">
    <props>
        <prop key="hibernate.dialect">org.hibernate.dialect.Oracle9Dialect</prop>
        <prop key="hibernate.show_sql">true</prop>
        <prop key="hibernate.format_sql">true</prop>
        <prop key="hibernate.use_sql_comments">true</prop>
        <prop key="hibernate.cglib.use_reflection_optimizer">true</prop>
        <prop key="hibernate.hbm2ddl.auto">update</prop>
        <prop key="hibernate.c3p0.min_size">5</prop>
        <prop key="hibernate.c3p0.max_size">20</prop>
        <prop key="hibernate.c3p0.timeout">1800</prop>
        <prop key="hibernate.c3p0.max_statements">50</prop>
        <prop key="hibernate.cache.provider_class">
                org.hibernate.cache.EhCacheProvider
        </prop>
        <prop key="hibernate.cache.use_second_level_cache">true</prop>
        <prop key="hibernate.cache.use_query_cache">true</prop>
    </props>
</property>
<property name="dataSource">
    <ref bean="dataSource" />
</property>

在我的实体中

@Entity
@Cache(usage=CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)

@Table(name = "TestPOJOCATEGORY")
@NamedQueries({
 @NamedQuery(name = "TestPOJOcategory.findAll",query = "SELECT h FROM TestPOJOcategory h"),@NamedQuery(name = "TestPOJOcategory.findById",query = "SELECT h FROM TestPOJOcategory h WHERE h.id = :id"),@NamedQuery(name = "TestPOJOcategory.findByCategoryname",query = "SELECT h FROM TestPOJOcategory h WHERE h.categoryname = :categoryname")})
public class TestPOJOcategory implements Serializable {

在我的道

public List<TestPOJOcategory> getAllCategory(final String keyword,final int nFirst,final int nPageSize,final String sortColumnId,final boolean bSortOrder) {

  List<TestPOJOcategory> result = (List<TestPOJOcategory>) getHibernateTemplate().execute(new HibernateCallback() {
    public Object doInHibernate(Session session) {
      Criteria crit = session.createCriteria(TestPOJOcategory.class,"TestPOJOcategory")
       .add(Restrictions.ilike("categoryname",keyword))
       .addOrder(bSortOrder ? Order.asc(sortColumnId) : Order.desc(sortColumnId))
       .setFirstResult(nFirst).setMaxResults(nPageSize);
      System.out.println("why still call from DB? suppose to call from cache");
      return crit.list();
    }
  });
  return result;
}

echcache.xml

<cache name="testonly.package.model.TestPOJOcategory"
        maxElementsInMemory="200"
        eternal="true"
        overflowToDisk="false"
        timeToIdleSeconds="300"
        timeToLiveSeconds="600"
    />

每次我调用dao时,它仍会从DB调用.为什么？

解决方法

首先,无论是否访问二级缓存,都会执行System.out.println()语句,因为此类访问是在list()方法中进行的.

其次,Criteria – 很像Query – 不会自动使用二级缓存;您指定的配置属性仅允许使用它.您仍然需要通过调用setCacheable(true)将每个Query / Criteria实例明确标记为可缓存：

Criteria crit = ...;
crit.setCacheable(true);
return crit.list();

另外,由于你正在使用HibernateTemplate,你可以正确使用它:-)并摆脱手动doInHibernate包装器：

public List<TestPOJOcategory> getAllCategory(final String keyword,final boolean bSortOrder) {

  DetachedCriteria crit = DetachedCriteria.forClass(TestPOJOcategory.class);
  crit.add(Restrictions.ilike("categoryname",keyword))
   .addOrder(bSortOrder ? Order.asc(sortColumnId) : Order.desc(sortColumnId));
  getHibernateTemplate().setCacheQueries(true); // works on both queries and criteria
  return (List<TestPOJOcategory>) getHibernateTemplate()
   .findByCriteria(crit,nFirst,nPageSize);
}

（编辑：李大同）

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