java - 如何在 Hibernate 中使用急切实例化？

Question

<!-- Clasa Proiect-->
<class catalog="tema3" name="com.tema3.tables.Proiect" table="proiect" lazy="false">
    <id column="proiect_id" name="id">
        <generator class="native"/>
    </id>
    <property name="nume"  type="text" />

    <set name="itemList" table="proiect_item" fetch="select">
        <key column="proiect_id"/>
        <many-to-many column="item_id" unique="true" class="com.tema3.tables.Item"/>
    </set>
</class>    </class>

这是我的映射类。
我称之为实例化的代码是:

Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
 Query q = session.createQuery("from Proiect");
 List<Proiect> lists = HibernateUtil.listAndCast(q);
 session.getTransaction().commit();
 obj = lists;

这是 listandCastMethod:

public static <T> List<T> listAndCast(Query q) {
    @SuppressWarnings("unchecked")
    List list = q.list();
    return list;
}

我不断收到:

May 2, 2011 4:38:03 PM org.hibernate.LazyInitializationException <init>
SEVERE: failed to lazily initialize a collection of role: com.tema3.tables.Proiect.itemList, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.tema3.tables.Proiect.itemList, no session or session was closed
 at   org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)

但问题是，Proiect 类的字段已填充，但出现此异常的项目集除外，但我希望填充项目集。我该怎么做？

Answer 1

在返回或调用 transaction.commit() 之前，初始化 listAndCast(Query q) 方法中的项目集。这可以通过调用项目集中的元素上的任何访问器来完成。这将强制 hibernate 初始化项目集而不是返回代理列表。

编辑

 Session session = HibernateUtil.getSessionFactory().getCurrentSession();
 session.beginTransaction();
 Query q = session.createQuery("from Proiect");
 List<Project> lists = HibernateUtil.listAndCast(q);
 if(lists != null && lists.size() > 0) {
    Set<Item> s = lists.get(0).getItemList();
    Iterator iter = s.iterator();
    while(iter.hasNext()) {
       Item item = iter.next();
       item.getSomething();
       break;
    }
 }
 session.getTransaction().commit();
 obj = lists;