我有2个表,即用户和联系人。 表是这个样子:在休眠状态下从多个表中检索数据
subscriber -> id, contact_id //contact_id is a foreign key
contact -> id, firstName, lastName, email, contactType
我Contact.hbm.xml文件看起来像这样:
<hibernate-mapping>
<class name="com.DBNAME.model.Contact" table="contact" >
<id name="id" type="int">
<column name="id" />
<generator class="identity" />
</id>
<property name="contactType" type="int">
<column name="contactType" sql-type="TINYINT"></column>
</property>
<property name="firstName" type="string">
<column name="firstName"></column>
</property>
<property name="lastName" type="string">
<column name="lastName"></column>
</property>
</class>
</hibernate-mapping>
而且我Subscriber.hbm.xml文件看起来像这样:
<hibernate-mapping>
<class name="com.DBNAME.model.Subscriber" table="subscriber" >
<id name="id" type="int">
<column name="id" />
<generator class="identity" />
</id>
<many-to-one name="contact" class="com.DBNAME.model.Contact" column="contact_id" unique="true" fetch="join"/>
</class>
</hibernate-mapping>
现在我想检索一个简单的订阅者对象,其中联系人自动映射。因此,我在Java代码中做的是:
/**
* get Subscribers
*/
@SuppressWarnings("unchecked")
private void getSubscribersWithContactDetails() {
Session session = HibernateUtils.getSessionFactory().getCurrentSession();
session.beginTransaction();
try {
setSubscribers((List<Subscriber>)session.createQuery("from Subscriber").list());
} catch (HibernateException e) {
session.getTransaction().rollback();
} finally {
session.getTransaction().commit();
}
}
/**
* @param subscribers the subscribers to set
*/
public void setSubscribers(List<Subscriber> subscribers) {
this.subscribers = subscribers;
}
我的数据类如下所示:
public class Contact implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private int contactType;
private String firstName;
private String lastName;
// Getters Setters and constructors
}
public class Subscriber implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private Contact contact; //Foreign Key from Contact -> id
private int contactId;
//Constructors, Getters and Setters
}
而且通过Hibernate生成我的查询看起来是这样的:
select subscriber0_.id as id1_, subscriber0_.contact_id as contact2_1_ from subscriber subscriber0_
我没有从联系人表中获取联系信息。我将如何做到这一点?
联系人对象为空,联系人内部的所有详细信息都设置为空。 – Ahmed 2012-04-13 19:43:01
在.hbm文件中使用'lazy = false'。你的情况确实如此,因为你得到空条目。 一旦你使用这个选项,它将把数据保存在订阅者中。 – instanceOfObject 2012-04-13 19:54:25