关于hibernate的多对一、一对多双向映射
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 {
private int id;
private String name;
private City city;
public City getCity() {
return city;
}
public void setCity(City city) {
this.city = city;
}
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;
}
}
City.java
package com.pk.po;
import java.util.Set;
public class City {
private int id;
private String name;
private Set cityes;
public Set getCityes() {
return cityes;
}
public void setCityes(Set cityes) {
this.cityes = cityes;
}
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;
}
}
ORM映射文件：
People.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="com.pk.po">
<class name="People" >
<id name="id">
<generator class="native"></generator>
</id>
<property name="name"></property>
<many-to-one name="city" column="cityid"></many-to-one>
</class>
</hibernate-mapping>
City.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="com.pk.po">
<class name="City">
<id name="id">
<generator class="native"></generator>
</id>
<property name="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
-->
<key column="cityid"></key>
<one-to-many class="People" />
</set>
</class>
</hibernate-mapping>
hibernate.cfg.xml
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_hql</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<property name="show_sql">true</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<mapping resource="com/pk/po/City.hbm.xml"/>
<mapping resource="com/pk/po/People.hbm.xml"/>
</session-factory>
</hibernate-configuration>
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