逆流而上的鲤鱼 2011-06-13
例子是city类和people类
双向关联映射:一个城市对应多个人;
多个人对应一个城市;
People.java
package com.pk.po;
public class People {
privateintid;
privateStringname;
privateCitycity;
publicCitygetCity(){
returncity;
}
publicvoidsetCity(Citycity){
this.city=city;
}
publicintgetId(){
returnid;
}
publicvoidsetId(intid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}}
City.java
package com.pk.po;
import java.util.Set;
public class City {
privateintid;
privateStringname;
privateSetcityes;
publicSetgetCityes(){
returncityes;
}
publicvoidsetCityes(Setcityes){
this.cityes=cityes;
}
publicintgetId(){
returnid;
}
publicvoidsetId(intid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
}ORM映射文件:
People.hbm.xml
<?xml version="1.0"?>
<!DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mappingpackage="com.pk.po">
<classname="People">
<idname="id">
<generatorclass="native"></generator>
</id>
<propertyname="name"></property>
<many-to-onename="city"column="cityid"></many-to-one>
</class>
</hibernate-mapping>City.hbm.xml
<?xml version="1.0"?>
<!DOCTYPEhibernate-mappingPUBLIC
"-//Hibernate/HibernateMappingDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mappingpackage="com.pk.po">
<classname="City">
<idname="id">
<generatorclass="native"></generator>
</id>
<propertyname="name"></property>
<set name="cityes" cascade="all" ><!--
在一对多时,在多的一方所产生的列的名称,应与多对一时的列的名字是相同的
-->
<keycolumn="cityid"></key>
<one-to-manyclass="People"/>
</set>
</class>
</hibernate-mapping>hibernate.cfg.xml
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/HibernateConfigurationDTD3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>
<session-factory>
<propertyname="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<propertyname="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_hql</property>
<propertyname="hibernate.connection.username">root</property>
<propertyname="hibernate.connection.password">root</property>
<propertyname="show_sql">true</property>
<propertyname="dialect">org.hibernate.dialect.MySQLDialect</property>
<mappingresource="com/pk/po/City.hbm.xml"/>
<mappingresource="com/pk/po/People.hbm.xml"/>
</session-factory>
</hibernate-configuration>