hibernate.cfg.xml :
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>
<session-factory>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.url">jdbc:mysql://localhost:3306/test</property>
<property name="connection.username">root</property>
<property name="connection.password">mysqladmin</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hbm2ddl.auto">update</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping resource="db/mapping/Person.hbm.xml"/>
</session-factory>
</hibernate-configuration>
Person.java :
public class Person {
private int id;
private String name;
private int age;
private List<String> schools=new ArrayList<String>();
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public List<String> getSchools() {
return schools;
}
public void setSchools(List<String> schools) {
this.schools = schools;
}
}
Person.hbm.xml :
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="db.domain">
<class name="Person" table="persons">
<id name="id" type="integer">
<generator class="native"/>
</id>
<property name="name" type="string">
<column name="name"></column>
</property>
<property name="age" type="integer">
<column name="age"></column>
</property>
<list name="schools" table="schools"> <!--用list元素-->
<key column="person_id" not-null="true"/>
<list-index column="schools_list_order"/>
<element type="string" column="school_name"/>
</list>
</class>
</hibernate-mapping>
Test.java :
public class Test {
public static void main(String[] args) {
Person p1=new Person();
p1.setName("tom");
p1.setAge(20);
List<String> schools1=new ArrayList<String>();
schools1.add("小学");
schools1.add("初中");
schools1.add("高中");
p1.setSchools(schools1);
Person p2=new Person();
p2.setName("jack");
p2.setAge(23);
List<String> schools2=new ArrayList<String>();
schools2.add("小学");
schools2.add("初中");
schools2.add("高中");
schools2.add("大学");
p2.setSchools(schools2);
Session session=HibernateSessionFactory.getSession();
Transaction txt=session.beginTransaction();
session.save(p1);
session.save(p2);
txt.commit();
HibernateSessionFactory.closeSession();
}
}
运行Test.java后,查看数据库:
对于同一个持久化对象而言,它所包含的集合元素的索引是不会重复的,因此List集合属性可以用关联持久化对象的外键和集合索引列作为联合主键。参看上图。
对于List集合属性,应该使用<List.../>元素完成映射,它有三个子元素:
名称 | 说明 |
<key.../> | 集合属性的值不可能与持久化类存储在同一个表内,集合属性会存放在另外的表中, 因此必须以外键关联,所以需要增加<key.../>元素来映射该外键列。 |
<list-index.../> | 映射List集合的索引列。 |
<element.../> | 当集合元素是基本类型及其包装类、字符串类型和日期类型时使用该元素。 |