Hibernate关联关系映射-----双向一对多/多对一映射配置

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。