映射Category一对多双向自身关联
Category类的类图：
categories表结构
创建表：
CREATE TABLE `categories` ( `id` bigint(20) NOT NULL, `name` varchar(15) default NULL, `category_id` bigint(20) default NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
创建Category类：
import java.util.Set;
public class Category
{
private Long id;
private String name;
private Category parentCategory;
private Set<Category> childCategory;
public Category(String name, Category parentCategory,
Set<Category> childCategory)
{
this.name = name;
this.parentCategory = parentCategory;
this.childCategory = childCategory;
}
public Category()
{
super();
}
public Long getId()
{
return id;
}
public void setId(Long id)
{
this.id = id;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public Category getParentCategory()
{
return parentCategory;
}
public void setParentCategory(Category parentCategory)
{
this.parentCategory = parentCategory;
}
public Set<Category> getChildCategory()
{
return childCategory;
}
public void setChildCategory(Set<Category> childCategory)
{
this.childCategory = childCategory;
}
}
创建Category.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="com.cdtax.hibernate.Category" table="categories" > <id name="id" column="id" type="long"> <generator class="increment"></generator> </id> <property name="name" type="string"> <column name="name" length="50"></column> </property> <set name="childCategory" cascade="all" inverse="true"> <key column="category_id"></key> <one-to-many class="com.cdtax.hibernate.Category"/> </set> <many-to-one name="parentCategory" column="category_id" class="com.cdtax.hibernate.Category"></many-to-one> </class> </hibernate-mapping>
因为是自身一对多，所以，配置表中就有set又有many-to-one
测试类，保存操作：
import java.util.HashSet;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class HibernateTest2
{
private static SessionFactory sessionFactory;
static
{
try
{
sessionFactory = new Configuration().configure()
.buildSessionFactory();
} catch (Exception ex)
{
ex.printStackTrace();
}
}
public static void main(String[] args) throws Exception
{
Session session = sessionFactory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Category category1 = new Category("leval1",null,new HashSet());
Category category2 = new Category("leval2",null,new HashSet());
Category category3 = new Category("leval2",null,new HashSet());
Category category4 = new Category("leval3",null,new HashSet());
Category category5 = new Category("leval3",null,new HashSet());
Category category6 = new Category("leval3",null,new HashSet());
Category category7 = new Category("leval3",null,new HashSet());
category2.setParentCategory(category1);
category3.setParentCategory(category1);
category1.getChildCategory().add(category2);
category1.getChildCategory().add(category3);
category3.getChildCategory().add(category4);
category3.getChildCategory().add(category5);
category4.setParentCategory(category3);
category5.setParentCategory(category3);
category2.getChildCategory().add(category6);
category2.getChildCategory().add(category7);
category6.setParentCategory(category2);
category7.setParentCategory(category2);
session.save(category1);
tx.commit();
}
catch(Exception ex)
{
if(null != tx)
{
tx.rollback();
}
ex.printStackTrace();
}
finally
{
session.close();
}
}
}
执行结果：
Hibernate: select max(id) from categories
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
Hibernate: insert into categories (name, category_id, id) values (?, ?, ?)
查询：
public static void main(String[] args) throws Exception
{
Session session = sessionFactory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Category category = (Category)session.get(Category.class, new Long(1));
System.out.println(category.getChildCategory().iterator().next().getName());
tx.commit();
}
catch(Exception ex)
{
if(null != tx)
{
tx.rollback();
}
ex.printStackTrace();
}
finally
{
session.close();
}
}
执行结果：
Hibernate: select category0_.id as id2_0_, category0_.name as name2_0_, category0_.category_id as category3_2_0_ from categories category0_ where category0_.id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
leval2
删除操作：
public static void main(String[] args) throws Exception
{
Session session = sessionFactory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Category category = (Category)session.get(Category.class, new Long(1));
// System.out.println(category.getChildCategory().iterator().next().getName());
session.delete(category);
tx.commit();
}
catch(Exception ex)
{
if(null != tx)
{
tx.rollback();
}
ex.printStackTrace();
}
finally
{
session.close();
}
}
执行结果：
Hibernate: select category0_.id as id2_0_, category0_.name as name2_0_, category0_.category_id as category3_2_0_ from categories category0_ where category0_.id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: select childcateg0_.category_id as category3_1_, childcateg0_.id as id1_, childcateg0_.id as id2_0_, childcateg0_.name as name2_0_, childcateg0_.category_id as category3_2_0_ from categories childcateg0_ where childcateg0_.category_id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?
Hibernate: delete from categories where id=?