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Hibernate关联关系映射-----双向一对多/多对一映射配置

2011-07-23 10:34 429 查看
实体:

package bi.one2many;

import java.util.HashSet;
import java.util.Set;

public class Emperor {
private int id;
private String name;
private Set<Minister> ministers = new HashSet<Minister>();

public Emperor() {

}

public Emperor(int id, String name, Set<Minister> ministers) {
super();
this.id = id;
this.name = name;
this.ministers = ministers;
}

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 Set<Minister> getMinisters() {
return ministers;
}

public void setMinisters(Set<Minister> ministers) {
this.ministers = ministers;
}

}

package bi.one2many;

public class Minister {
private int id;
private String name;
private Emperor emperor;

public Minister() {

}

public Minister(int id, String name, Emperor emperor) {
super();
this.id = id;
this.name = name;
this.emperor = emperor;
}

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 Emperor getEmperor() {
return emperor;
}

public void setEmperor(Emperor emperor) {
this.emperor = emperor;
}

}


  

hbm配置文件:

<hibernate-mapping>
<class name="bi.one2many.Emperor">
<id name="id" column="did">
<generator class="native" />
</id>
<property name="name" type="string" column="name"></property>

<!-- confirure the uniredirection association -->
<set name="ministers" inverse="true" cascade="all">
<key column="did" not-null="true"></key>
<one-to-many class="bi.one2many.Minister"/>
</set>
</class>

</hibernate-mapping>
<hibernate-mapping>
<class name="bi.one2many.Minister">
<id name="id" column="mid">
<generator class="native" />
</id>
<property name="name" type="string" column="name"></property>
<many-to-one name="emperor" column="did" cascade="all"></many-to-one>
</class>

</hibernate-mapping>


  

测试文件:

public class Test {

@org.junit.Test
public void testAdd() {
SessionFactory sf = HibernateUtil.getSessionFactory();
Session session = sf.getCurrentSession();
session.beginTransaction();

Minister m1 = new Minister();
m1.setName("廉颇");

Minister m2 = new Minister();
m2.setName("蔺相如");

Emperor emperor = new Emperor();
emperor.setName("齐威王");
//emperor.getMinisters().add(m1);
//session.save(emperor);

m1.setEmperor(emperor);
m2.setEmperor(emperor);

session.save(m1);
session.save(m2);
session.beginTransaction().commit();
}
}


  

测试结果:

Hibernate: insert into Emperor (name) values (?)
Hibernate: insert into Minister (name, did) values (?, ?)
Hibernate: insert into Minister (name, did) values (?, ?)


  

在双向关联关系配置中有inverse属性和cascade属性比较让人迷糊,不过参看一下这个文章写得蛮清楚的:

Hibernate中的Inverse和cascade属性配置

http://www.cnblogs.com/focusj/archive/2011/03/23/2057603.html
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