Hibernate 3多对多单向连接表关联简单示例

多对多单向连接表关联：只要一个端有Set就可以了，在<set>的属性中指明POJO中的Set集合，对应的链接表名，子元素<key>声明本端对应的连接表中的主键，<many-to-many>声明对应的连接表中的另一端的主键及其对应的POJO类。

示例：
一个Person可以有多个Address，一个Address也可以有多个Person

POJO如下：
public class Addressnn implements java.io.Serializable{
    private int addressid;
    private String addressdetail;

    public Addressnn(){

    }
    public Addressnn(String addressdetail){
        this.addressdetail=addressdetail;
    }

    public void setAddressid(int addressid){
        this.addressid=addressid;
    }
    public int getAddressid(){
        return this.addressid;
    }

    public void setAddressdetail(String addressdetail){
        this.addressdetail=addressdetail;
    }
    public String getAddressdetail(){
        return this.addressdetail;
    }
}

 

public class Personnn implements java.io.Serializable{
    private int personid;
    private String name;
    private int age;
    private java.util.Set addresses=new java.util.HashSet();

    public void setPersonid(int personid){
        this.personid=personid;
    }
    public int getPersonid(){
        return this.personid;
    }
    public void setName(String name){
        this.name = name;
    }
    public String getName(){
        return this.name;
    }
    public void setAge(int age){
        this.age=age;
    }
    public int getAge(){
        return this.age;
    }

    public void setAddresses(java.util.Set addresses){
        this.addresses = addresses;
    }
    public void addAddress(Addressnn ad){
        this.getAddresses().add(ad);
    }
    public java.util.Set getAddresses(){
        return this.addresses;
    }
}

hbm.xml如下：
<!--Personnn.hbm.xml-->
<hibernate-mapping>
    <class name="com.Personnn" table="person_nn">
        <id column="personid" name="personid" type="int">
            <generator class="native"/>
        </id>
        <property name="name" column="name" type="string"/>
        <property name="age" column="age" type="int"/>
         <!--映射集合属性，join_nn是连接表表名-->
         <set name="addresses" table="join_nn">
             <key column="personid"/>
             <many-to-many column="addressid" class="com.Addressnn"/>
         </set>
    </class>
</hibernate-mapping>

<!--Addressnn.hbm.xml-->
<hibernate-mapping>
    <class name="com.Addressnn" table="address_nn">
        <id column="addressid" name="addressid" type="int">
            <generator class="native"/>
        </id>
        <property name="addressdetail" column="addressdetail" type="string"/>
    </class>
</hibernate-mapping>

数据库表如下：
mysql> desc person_nn;
 
+----------+--------------+------+-----+---------+----------------+
 
| Field     | Type | Null | Key | Default | Extra???? ?????|
 
+----------+--------------+------+-----+---------+----------------+
 
| personid | int(11)      | NO  | PRI | NULL    | auto_increment |
 
| name     | varchar(255) | YES |     | NULL    |                |
 
| age      | int(11)      | YES |     | NULL    |                |
 
+----------+--------------+------+-----+---------+----------------+
 
 
 
mysql> desc join_nn;
 
+-----------+---------+------+-----+---------+-------+
 
| Field     | Type    | Null | Key | Default | Extra |
 
+-----------+---------+------+-----+---------+-------+
 
| personid  | int(11) | NO   | PRI |         |       |
 
| addressid | int(11) | NO   | PRI |         |       |
 
+-----------+---------+------+-----+---------+-------+
 
 
 
mysql> desc person_nn;
 
+----------+--------------+------+-----+---------+----------------+
 
| Field    | Type         | Null | Key | Default | Extra          |
 
+----------+--------------+------+-----+---------+----------------+
 
| personid | int(11)      | NO   | PRI | NULL    | auto_increment |
 
| name     | varchar(255) | YES  |     | NULL    |                |
 
| age      | int(11)      | YES  |     | NULL    |                |
 
+----------+--------------+------+-----+---------+----------------+
 

main测试：

public class Test_nn {
    public static void main(String args[]){
        Addressnn add1=new Addressnn();
        Addressnn add2=new Addressnn();
        Addressnn add3=new Addressnn();
        Personnn p1=new Personnn();
        Personnn p2=new Personnn();

        add1.setAddressdetail("郑州市经三路");
        add2.setAddressdetail("合肥市宿州路");
        add3.setAddressdetail("北京市长安路");
        p1.setName("wang");
        p1.setAge(30);
        p2.setName("lee");
        p2.setAge(50);

        p1.getAddresses().add(add1);
        p1.getAddresses().add(add2);
        p2.getAddresses().add(add2);
        p2.getAddresses().add(add3);

        Session session=HibernateUtil.getSession();
        Transaction t=session.beginTransaction();
        session.save(add1);
        session.save(add2);
        session.save(add3);
        session.save(p2);
        session.save(p1);
        t.commit();

        HibernateUtil.closeSession();
    }
}

 

评论

1 楼 zan2222 2010-09-15