Question

我有2个班级：

用户

RentedCar

public class User implements Serializable{
    private String userName;
    private Integer userId;
    private String userParent;
}

public class RentedCar implements Serializable{
    private Date stopDate;
    private Date startDate;
    private String carName;
    private Integer carId;
    private Integer userId;   // Some userId from User.
}

这些类有各自的hbm.xml个文件。基础表是不相关的。这意味着我知道userId中的RentedCar与userId中的User相关联，但它们之间没有PK / FK关系。我需要在many-to-one和RentedCar之间添加User关联，并在one-to-many和User之间添加RentedCar关联。我应该如何在hbm.xml文件中执行此操作？

这些是xml映射：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 <hibernate-mapping>
    <class name="User" table="user">
        <composite-id>
            <key-property name="userName" column="user_name" type="string"/>
            <key-property name="userParent" column="user_parent" type="string"/>
        </composite-id>
        <property name="userId" column="user_id" type="int"></property>
    </class>
 </hibernate-mapping>



<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 <hibernate-mapping>
    <class name="RentedCar" table="rented_car">
        <composite-id>
            <key-property name="stopDate" column="stop_date" type="date" />
            <key-property name="carId" column="car_id" type="int" />
            <key-property name="userId" column="user_id" type="int" />
        </composite-id>
        <property name="startDate" column="start_date" type="date"></property>
        <property name="carName" column="car_name" type="float"></property>
    </class>
 </hibernate-mapping>

Answer 1

我认为你的课程中应该有一些东西表明在hbm.xml文件中有一对多的关系：

public class User implements Serializable{
    private String userName;
    private Integer userId;
    private String userParent;
    private Set<RentedCar> rentedCars;
}

public class RentedCar implements Serializable{
    private Date stopDate;
    private Date startDate;
    private String carName;
    private Integer carId;
    private User user; 
}

然后在RentedCar.hbm.xml中你可以使用：

<many-to-one name="user" class="User">
        <column name="userId" not-null="true"></column>
 </many-to-one>

在User.hbm.xml中：

<set name="rentedCars" table="rented_car" fetch="select">
     <key>
          <column name="userId" not-null="true"></column>
     </key>
     <one-to-many class=" RentedCar "/>
 </set>

本教程可以帮助您http://www.tutorialspoint.com/hibernate/hibernate_one_to_many_mapping.htm

Hibernate - 映射xml中不相关对象的关联

1 个答案: