Question

我正在hibernate的帮助下开发一个电子购物程序。因为我在jsp，servlet，hibernate上是一个非常新鲜的初学者，我不知道如何在关系表中使用附加列进行多对多关系映射。我已经阅读了几个教程，但大多数都专注于注释映射和hibernate社区的文档，但它们都不适合我的情况。

我有三个表movie_information，order_和order_details（关系），其中order_details的结构如下所示。

order_details
-------------
order_id FK
movie_id FK
quantity
-------------

我正在尝试使用四个POJO类来实现多对多关系。这是代码。

MovieInformation.java

// other variable, constructor, getter, setter
private Set<OrderDetails> orderDetails = new HashSet<OrderDetails>();

Order.java

// other variable, constructor, getter, setter
private Set<OrderDetails> orderDetails = new HashSet<OrderDetails>();

OrderDetails.java

private OrderDetailsPK primaryKey;
private Order order;
private MovieInformation movie;
private int quantity;

OrderDetailsPK.java

private long orderId;
private long movieId;

MovieInformation.hbm.xml

<id column="movie_id" name="movieId" type="long">
    <generator class="native"/>
</id>

 // some property

<set name="orderDetails" table="order_details" inverse="true" lazy="true" fetch="select">
    <key>
        <column name="movie_id" not-null="true" />
    </key>
    <one-to-many class="cart.hibernate.orderDetails.orderDetails" />
</set>

Order.hbm.xml

<id column="order_id" name="orderId" type="long">
    <generator class="native"/>
</id>

//some properties

<set name="orderDetails" table="order_details" inverse="true" lazy="true" fetch="select">
    <key>
        <column name="order_id" not-null="true" />
    </key>
    <one-to-many class="cart.hibernate.orderDetails.orderDetails" />
</set>

OrderDetails.hbm.xml

<composite-id name="orderDetailsPK" class="cart.hibernate.orderDetailsPK.OrderDetailsPK">
  <key-property column="order_id" name="orderId" type="long"/>
  <key-property column="movie_id" name="movieId" type="long"/>
</composite-id>

<many-to-one name="order" class="cart.hibernate.order.Order" insert="false" update="false"/>
<many-to-one name="movie" class="cart.hibernate.movieInformation.MovieInformation" insert="false" update="false"/>
<property column="quantity" name="quantity" type="int"/>

OrderDetailsPK.hbm.xml

<class name="cart.hibernate.orderDetailsPK.OrderDetailsPK" >
  <property  name="orderId" type="long"/>
<property name="movieId" type="long"/>

hibernate.cfg.cml

<mapping class="cart.hibernate.MovieInformation" package="cart.hibernate.movieInformation" resource="cart/hibernate/movieInformation/MovieInformation.hbm.xml"/>        
<mapping class="cart.hibernate.Order" package="cart.hibernate.order" resource="cart/hibernate/order/Order.hbm.xml"/>
<mapping class="cart.hibernate.OrderDetails" package="cart.hibernate.orderDetails" resource="cart/hibernate/orderDetails/OrderDetails.hbm.xml"/>
<mapping class="cart.hibernate.OrderDetailsPK" package="cart.hibernate.orderDetailsPK" resource="cart.hibernate.orderDetailsPK/OrderDetailsPK.hbm.xml"/>

当我尝试运行测试主方法时，从程序抛出异常

887 [main] INFO org.hibernate.cfg.Configuration - Reading mappings from resource : 
cart.hibernate.orderDetailsPK/OrderDetailsPK.hbm.xml
Initial SessionFactory creation failed.org.hibernate.MappingNotFoundException: resource: cart.hibernate.orderDetailsPK/OrderDetailsPK.hbm.xml not found
Exception in thread "main" java.lang.ExceptionInInitializerError
    at cart.hibernate.HibernateUtil.buildSessionFactory(HibernateUtil.java:28)
    at cart.hibernate.HibernateUtil.<clinit>(HibernateUtil.java:18)
    at cart.hibernate.order.ManageOrder.main(ManageOrder.java:40)
Caused by: org.hibernate.MappingNotFoundException: resource: cart.hibernate.orderDetailsPK/OrderDetailsPK.hbm.xml not found
    at org.hibernate.cfg.Configuration.addResource(Configuration.java:799)
    at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:2344)
    at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:2310)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2290)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2243)
    at org.hibernate.cfg.Configuration.configure(Configuration.java:2158)
    at cart.hibernate.HibernateUtil.buildSessionFactory(HibernateUtil.java:23)
    ... 2 more

在我读完其他人的问题之后，我相信我的代码中的错误是由错误的映射代码引起的。希望你们能帮助我解决这个问题。如果提供了一些带有额外列的多对多映射的简单示例，那就太好了。

Answer 1

我相信你的代码是干净的，因为控制台告诉你MappingNotFoundException一旦加载了hibernate文件，它就找不到了。确保模型bean包中的hibernate文件不在源代码中。

使用hibernate XML映射与额外列映射多对多关系的困难

1 个答案: