Java 一对多关联的二级缓存

我正在使用Hibernate 3.2.5

我在

部门

和

培训

表之间有一对多关系。启用二级缓存（使用EHCache），并在

dept.cfg.xml

和`training.hbm.xml文件中创建以下条目以缓存数据

<cache usage="read-only" />

我在dept.hbm.xml文件中提到了映射，如下所示：

//Mappings between POJO and DB Table
<map name="trainingDetails" inverse="false" cascade="delete" lazy="false">
      <key column="DEPT_ID"></key>          
      <map-key formula="ID" type="integer"></map-key>
      <one-to-many class="com.model.Training"/>          
</map>

---

请告诉我我遗漏了什么以及如何解决此问题。

如果您告诉Hibernate将

部门

实体缓存在二级缓存中，对于每个缓存的

部门

，它将存储

deptId

和

deptName

字段的值。但是，默认情况下，它不存储

trainingDetails

字段的内容。如果从二级缓存中读取部门，并且应用程序需要访问成员字段，Hibernate将转到数据库以确定集合的当前成员

如果希望Hibernate缓存members字段的内容，则需要通过向

members

声明中添加

cache

元素来告诉它这样做：

//Mappings between POJO and DB Table
<map name="trainingDetails" inverse="false" cascade="delete" lazy="false">
      <!-- Cache the ids of entities are members of this collection -->
      <cache usage="read-only" />
      <key column="DEPT_ID"></key>          
      <map-key formula="ID" type="integer"></map-key>
      <one-to-many class="com.model.Training"/>          
</map>

//POJO和DB表之间的映射

SessionFactory sf = new Configuration().configure("trial.cfg.xml").buildSessionFactory();
    Session session = sf.openSession();

    Dept department = (Dept)session.load(Dept.class, 1);
    //Some business related operations
    session.flush();
    session.close();
            //Some operations
            Session session1 = sf.openSession();        
    Dept department1 = (Dept)session1.load(Dept.class, 1);
    //Here I can see in the console the query for fetching the 
    //training details for the department is getting executed again
    //but the Department details is getting fetched from the Cache - WHY?
    //I want the Training details also to be fetched from the cache.
    session1.flush();
    session1.close();

//Mappings between POJO and DB Table
<map name="trainingDetails" inverse="false" cascade="delete" lazy="false">
      <!-- Cache the ids of entities are members of this collection -->
      <cache usage="read-only" />
      <key column="DEPT_ID"></key>          
      <map-key formula="ID" type="integer"></map-key>
      <one-to-many class="com.model.Training"/>          
</map>