Hibernate从零开始_05_一对多关系
1、POJO的建立
/**
* 客户表
*/
public class TbUser {
private Long id;
private String name;
private Long age;
private String city;
//订单
private Set<Order> orders = new HashSet<Order>();
public TbUser(){
}
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 Long getAge() {
return age;
}
public void setAge(Long age) {
this.age = age;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
@Override
public String toString() {
return "TbUser [id=" + id + ", name=" + name + ", age=" + age
+ ", city=" + city + "]";
}
public Set<Order> getOrders() {
return orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}
}
/**
* 订单表
*/
public class Order {
private Long id;
private String addr;
private Long totalprice;
//用户
private TbUser user;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getAddr() {
return addr;
}
public void setAddr(String addr) {
this.addr = addr;
}
public Long getTotalprice() {
return totalprice;
}
public void setTotalprice(Long totalprice) {
this.totalprice = totalprice;
}
public TbUser getUser() {
return user;
}
public void setUser(TbUser user) {
this.user = user;
}
@Override
public String toString() {
return "Order [id=" + id + ", addr=" + addr + ", totalprice="
+ totalprice + ", user=" + user + "]";
}
}
2、POJO.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 映射关系配置 name="POJO类" table="表单名称" catalog="数据库名称，若不指定则使用jdbc中的配置" --> <class name="com.study.hibernate.domain.TbUser" table="tb_user" catalog="db_hibernate" select-before-update="true"> <!-- 配置主键 name="POJO中对应属性" colum="表单中主键名" type="数据类型" --> <id name="id" column="id" type="java.lang.Long"> <!-- 主键的生成方式。native：根据底层数据库自动选择 --> <generator class="native"></generator> </id> <property name="name" column="name" type="java.lang.String"></property> <property name="age" column="age" type="java.lang.Long"></property> <property name="city" column="city" type="java.lang.String"></property> <!-- 此处的name是对应实体对象中的属性名 --> <!-- cascade级联操作 save-update为自动保存-修改 --> <set name="orders" cascade="save-update"> <!-- 此处的column是对应Order.hbm.xml中many-to-one的column="tb_user_id" --> <key column="tb_user_id"/> <one-to-many class="com.study.hibernate.domain.Order"/> </set> </class> </hibernate-mapping>
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 映射关系配置 name="POJO类" table="表单名称" catalog="数据库名称，若不指定则使用jdbc中的配置" --> <class name="com.study.hibernate.domain.Order" table="tb_order" catalog="db_hibernate"> <!-- 配置主键 name="POJO中对应属性" colum="表单中主键名" type="数据类型" --> <id name="id" column="id" type="java.lang.Long"> <!-- 主键的生成方式。native：根据底层数据库自动选择 --> <generator class="native"></generator> </id> <property name="addr" column="addr" type="java.lang.String"></property> <property name="totalprice" column="totalprice" type="java.lang.Long"></property> <many-to-one name="user" class="com.study.hibernate.domain.TbUser" column="tb_user_id" /> </class> </hibernate-mapping>
3、测试
1）级联保存
public void saveTest(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
TbUser u = new TbUser();
u.setName("tl");
u.setAge(25L);
u.setCity("beijing");
Order o1 = new Order();
o1.setAddr("ccccc");
o1.setTotalprice(100L);
Order o2 = new Order();
o2.setAddr("ssssss");
o2.setTotalprice(200L);
u.getOrders().add(o1);
u.getOrders().add(o2);
o1.setUser(u);
o2.setUser(u);
session.save(u);
//当<set> cascade='save-update'时不用写下面保存代码也可保存
// session.save(o1); // (1)
// session.save(o2); // (2)
transaction.commit();
session.close();
sessionFactory.close();
//当没有配置cascade='save-update'并取消(1)(2)注释时
//结果1
// Hibernate: /* insert com.study.hibernate.domain.TbUser */ insert into db_hibernate.tb_user (name, age, city) values (?, ?, ?)
// Hibernate: /* insert com.study.hibernate.domain.Order */ insert into db_hibernate.tb_order (addr, totalprice, tb_user_id) values (?, ?, ?)
// Hibernate: /* insert com.study.hibernate.domain.Order */ insert into db_hibernate.tb_order (addr, totalprice, tb_user_id) values (?, ?, ?)
// Hibernate: /* create one-to-many row com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=? where id=?
// Hibernate: /* create one-to-many row com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=? where id=?
//结果2：为没有执行session.save(o1); session.save(o2); Hibernate 自动执行保存O1,O2对象并与user关联
// Hibernate: /* insert com.study.hibernate.domain.TbUser */ insert into db_hibernate.tb_user (name, age, city) values (?, ?, ?)
// Hibernate: /* insert com.study.hibernate.domain.Order */ insert into db_hibernate.tb_order (addr, totalprice, tb_user_id) values (?, ?, ?)
// Hibernate: /* insert com.study.hibernate.domain.Order */ insert into db_hibernate.tb_order (addr, totalprice, tb_user_id) values (?, ?, ?)
// Hibernate: /* create one-to-many row com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=? where id=?
// Hibernate: /* create one-to-many row com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=? where id=?
}
2）级联查询
/**
* 多对一查询
*/
@Test
public void queryTest2(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
String hql = "from Order o where o.id=1";
Query query = session.createQuery(hql);
Order o = (Order) query.uniqueResult();
System.out.println(o);
transaction.commit();
session.close();
sessionFactory.close();
//结果
// Hibernate: /* from Order o where o.id=1 */ select order0_.id as id1_0_, order0_.addr as addr2_0_, order0_.totalprice as totalpri3_0_, order0_.tb_user_id as tb_user_4_0_ from db_hibernate.tb_order order0_ where order0_.id=1
// Hibernate: /* load com.study.hibernate.domain.TbUser */ select tbuser0_.id as id1_1_0_, tbuser0_.name as name2_1_0_, tbuser0_.age as age3_1_0_, tbuser0_.city as city4_1_0_ from db_hibernate.tb_user tbuser0_ where tbuser0_.id=?
// Order [id=1, addr=sjz, totalprice=100, user=TbUser [id=12, name=wangliu, age=12, city=bj]]
}
/**
* 一对多查询
*/
//@Test
public void queryTest3(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
String hql = "from TbUser t where t.id=12";
Query query = session.createQuery(hql);
TbUser t = (TbUser) query.uniqueResult();
System.out.println(t);
Iterator<Order> it =t.getOrders().iterator();
while (it.hasNext()) {
System.out.println(it.next());
}
transaction.commit();
session.close();
sessionFactory.close();
//结果
// Hibernate: /* from TbUser t where t.id=12 */ select tbuser0_.id as id1_1_, tbuser0_.name as name2_1_, tbuser0_.age as age3_1_, tbuser0_.city as city4_1_ from db_hibernate.tb_user tbuser0_ where tbuser0_.id=12
// TbUser [id=12, name=wangliu, age=12, city=bj]
// Hibernate: /* load one-to-many com.study.hibernate.domain.TbUser.orders */ select orders0_.tb_user_id as tb_user_4_1_1_, orders0_.id as id1_0_1_, orders0_.id as id1_0_0_, orders0_.addr as addr2_0_0_, orders0_.totalprice as totalpri3_0_0_, orders0_.tb_user_id as tb_user_4_0_0_ from db_hibernate.tb_order orders0_ where orders0_.tb_user_id=?
// Order [id=2, addr=shanghai, totalprice=211, user=TbUser [id=12, name=wangliu, age=12, city=bj]]
// Order [id=1, addr=sjz, totalprice=100, user=TbUser [id=12, name=wangliu, age=12, city=bj]]
}
3)级联删除
<set name="orders" cascade="delete">
/**
* 级联删除操作
*/
@Test
public void deleteTest2(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
TbUser u = new TbUser();
u.setId(21L);
session.delete(u);
transaction.commit();
session.close();
sessionFactory.close();
//结果
// Hibernate: /* delete one-to-many com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=null where tb_user_id=?
// Hibernate: /* delete com.study.hibernate.domain.TbUser */ delete from db_hibernate.tb_user where id=?
}
结果：
客户被删除客户所对应的订单的关联ID被设置为NULL。
4）孤子删除
<set name="orders" cascade="delete-orphan">
/**
* 级联删除操作--孤子删除
*/
//@Test
public void deleteTest3(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
TbUser u = (TbUser) session.get(TbUser.class, 22L);
Order o1 = (Order) session.get(Order.class,new Long(21));
//Order o2 = new Order();
u.getOrders().remove(o1);
//session.delete(u);
transaction.commit();
session.close();
sessionFactory.close();
//结果
// Hibernate: /* load com.study.hibernate.domain.Order */ select order0_.id as id1_0_0_, order0_.addr as addr2_0_0_, order0_.totalprice as totalpri3_0_0_, order0_.tb_user_id as tb_user_4_0_0_ from db_hibernate.tb_order order0_ where order0_.id=?
// Hibernate: /* delete one-to-many com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=null where tb_user_id=?
// Hibernate: /* delete com.study.hibernate.domain.TbUser */ delete from db_hibernate.tb_user where id=?
//当cascade="delete-orphan"
//u.getOrders().remove(o1);
//结果
// Hibernate: /* load com.study.hibernate.domain.TbUser */ select tbuser0_.id as id1_1_0_, tbuser0_.name as name2_1_0_, tbuser0_.age as age3_1_0_, tbuser0_.city as city4_1_0_ from db_hibernate.tb_user tbuser0_ where tbuser0_.id=?
// Hibernate: /* load com.study.hibernate.domain.Order */ select order0_.id as id1_0_0_, order0_.addr as addr2_0_0_, order0_.totalprice as totalpri3_0_0_, order0_.tb_user_id as tb_user_4_0_0_ from db_hibernate.tb_order order0_ where order0_.id=?
// Hibernate: /* load one-to-many com.study.hibernate.domain.TbUser.orders */ select orders0_.tb_user_id as tb_user_4_1_1_, orders0_.id as id1_0_1_, orders0_.id as id1_0_0_, orders0_.addr as addr2_0_0_, orders0_.totalprice as totalpri3_0_0_, orders0_.tb_user_id as tb_user_4_0_0_ from db_hibernate.tb_order orders0_ where orders0_.tb_user_id=?
// Hibernate: /* delete one-to-many row com.study.hibernate.domain.TbUser.orders */ update db_hibernate.tb_order set tb_user_id=null where tb_user_id=? and id=?
// Hibernate: /* delete com.study.hibernate.domain.Order */ delete from db_hibernate.tb_order where id=?
}
原始数据：
删除后数据：
