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hibernate的数据关联映射

2024-07-13 05:16:00   221人阅读

数据关联映射分为：一对多、多对一，一对一，多对多。

cascade属性
• save-update：在执行保存和修改是进行级联操作
• delete：在执行删除时进行级联操作
• all：在所有情况下进行级联操作
• none：不进行级联操作（默认）

抓取策略

 

一对多、多对一

一对多、多对一持久化类设计// User类public class User {  private int id; private String name; private int age; private Set<Address> addressSet;  //get set method }//Address类public class Address {  private int id; private String address; private int tel; private User user;  //get set method }
address.hbm.xml<hibernate-mapping package="com.hussion.pojo">     <class name="Address" table="t_address">         <id name="id">           <generator class="native"/>         </id>         <property name="address"></property>         <property name="tel"></property>         <many-to-one name="user" class="User" column="userid"/>     </class> </hibernate-mapping>
user.hbm.xml<hibernate-mapping package="com.hussion.pojo">      <class name="User" table="t_user">         <id name="id" column="id">           <generator class="native"></generator>         </id>         <property name="name" column="name"></property>         <property name="age" column="age"></property>         <!--inverse="true"放弃关系维护-->         <set name="addressSet" inverse="true">           <key column="userid"/>           <one-to-many class="Address"/>         </set>     </class>  </hibernate-mapping>

一对一

持久化类设计public class Person {  private int id; private String userName; private Card card;  //get set Method } public class Card {  private int id; private String cardNum; private Person person;  //get set Method }
person.hbm.xml<hibernate-mapping package="com.hussion.pojo">     <class name="Person" table="t_person">         <id name="id">           <generator class="native"></generator>         </id>          <property name="userName"></property>           <one-to-one name="card" class="Card" cascade="delete"/>    </class> </hibernate-mapping>

多对多

ublic class Teacher {  private int id; private String name; private Set<Student> student;  //get set method } public class Student {  private int id; private String name; private Set<Teacher> teacher;  //get set method }
teacher.hbm.xml<hibernate-mapping package="com.hussion.pojo">     <class name="Teacher" table="t_teacher">         <id name="id" column="id">           <generator class="native"></generator>         </id>           <property name="name"></property>         <set name="student" table="t_student_techer">           <key column="teacherid"/>           <many-to-many class=“Student” column=“studentid”/>         </set>     </class> </hibernate-mapping>
student.hbm.xml<hibernate-mapping package="com.hussion.pojo">     <class name="Student" table="t_student">         <id name="id" column="id">           <generator class="native"></generator>         </id>         <property name="name"></property>         <set name="teacher" table="t_student_techer">             <key column="studentid"/>             <many-to-many class="Teacher" column="teacherid />         </set>     </class> </hibernate-mapping>

多对多一方要放弃关系维护<set name="student" table="t_teacher_student"  inverse="true">排序<many-to-many class="Student" column="s_id"  order-by="id asc,name desc"></many-to-many>

延迟加载关闭 ： lazy="false"


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