Hibernate映射
？代理对象是不是只可以获取id，而不能修改id
实验结果是：代理对象可以正常获取其id值，但一旦setId，不管会不会成功都会查询其所在的表，即进行加载
但若只是set代理对象则不需要查询其表
在页面上使用<s:debug></s:debug>会产生莫名的错误，
如在对用户进行修改时明明没有使用到用户的commentSet属性，但还是报了它的懒加载异常。
/*
* 1. 声明集合类型时, 需使用接口类型, 因为 hibernate 在获取
* 集合类型时, 返回的是 Hibernate 内置的集合类型, 而不是 JavaSE 一个标准的
* 集合实现.
* 2. 需要把集合进行初始化, 可以防止发生空指针异常
*/
private Set<Order> orders = new HashSet<>();
单项n21
Customer.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">
<!-- Generated 2017-2-19 13:51:15 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_danxiang_n21">
<class name="Customer" table="CUSTOMERS">
<id name="customerId" type="java.lang.Integer">
<column name="CUSTOMER_ID" />
<generator class="native" />
</id>
<property name="customerName" type="java.lang.String">
<column name="CUSTOMER_NAME" />
</property>
</class>
</hibernate-mapping>
Order.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">
<!-- Generated 2017-2-19 13:51:15 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_danxiang_n21">
<class name="Order" table="ORDERS">
<id name="orderId" type="java.lang.Integer">
<column name="ORDER_ID" />
<generator class="native" />
</id>
<property name="orderDesc">
<column name="ORDER_DESC" sql-type="mediumtext" />
</property>
<!-- name：为Order中表示与 一的一端Customer类的 联系的属性名
class：为一的一端的全类名
column：为ORDERS表中的外键的字段名 -->
<many-to-one name="customer" class="Customer">
<column name="CUSTOMER_ID" />
</many-to-one>
</class>
</hibernate-mapping>
Test.java
package model_danxiang_n21;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class HibernateTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void testMany2OneSave() {
Customer customer = new Customer();
customer.setCustomerName("Ji");
Order order1 = new Order("AA", customer);
Order order2 = new Order("BB", customer);
//这种顺序三条insert
// session.save(customer);
// session.save(order1);
// session.save(order2);
//这种顺序显示三条insert再是一条update
session.save(order1);
session.save(customer);
session.save(order2);
}
@Test
public void testMany2OneGet() {
Order order = (Order) session.get(Order.class, 3);//这是仅仅查询了Order
System.out.println(order.getOrderDesc());
//直到执行过下面这行代码，才会打印select customer 的sql语句。此为延时加载。若此时session被close则会出懒加载异常
System.out.println(order.getCustomer().getCustomerName());
}
@Test
public void testMany2OneUpdate(){
Order order = (Order) session.get(Order.class, 1);
order.getCustomer().setCustomerName("Fei");
}
@Test
public void testMany2OneDelete(){
Order order = new Order();
order.setOrderId(2);
session.delete(order);
Customer customer = new Customer();
customer.setCustomerId(1);
session.delete(customer);
//customer是orders中的外键，所以当orders表中有order与此customer关联，则删除customer会报异常；若无则可删除
}
}
单项n2n
He.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">
<!-- Generated 2017-2-21 17:15:59 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="model_danxiang_n2n.He" table="HES">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<set name="set" table="HE_YU" inverse="false" lazy="true">
<key>
<column name="H_ID" />
</key>
<many-to-many column="Y_ID" class="model_danxiang_n2n.Yu"></many-to-many>
</set>
</class>
</hibernate-mapping>
Yu.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">
<!-- Generated 2017-2-21 17:15:59 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="model_danxiang_n2n.Yu" table="YUS">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
</class>
</hibernate-mapping>
Test.java
package model_danxiang_n2n;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class Test_danxiang_n2n {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void testSave() {
Yu yu1 = new Yu();
Yu yu2 = new Yu();
He he1 = new He();
He he2 = new He();
yu1.setName("yun1");
yu2.setName("yun2");
he1.setName("ji1");
he2.setName("ji2");
he1.getSet().add(yu1);
he1.getSet().add(yu2);
he2.getSet().add(yu1);
session.save(he1);
session.save(he2);
session.save(yu1);
session.save(yu2);
//无update，只有7条insert
}
@Test
public void testGet(){
He he = (He) session.get(He.class, 1);
System.out.println(he.getName());
System.out.println(he.getSet().size());
}
}
双向n21
Customer.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">
<!-- Generated 2017-2-19 16:01:24 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_shuangxiang_n21">
<class name="Customer" table="CUSTOMERS">
<id name="customerId" type="java.lang.Integer">
<column name="CUSTOMER_ID" />
<generator class="native" />
</id>
<property name="customerName" type="java.lang.String">
<column name="CUSTOMER_NAME" />
</property>
<!-- set为1方中记录多方的属性名
inverse:为true时就不用update，因为此时customer是被动方，无需主动添加关联
若不设置则1方和n方都为主动方就都需要添加关联
table：为n的一方在数据库中存的表
column：为n方表中的1方的外键字段名
one-to-many class：中写n方的全类名
-->
<!-- （不建议使用，建议使用手工的方式）
cascade:不写时，此时级联删除会报异常；若想清空set，则数据库不会有变化；
若只save 1的一方，则与之相关联的n的对象不会被保存
delete，此时删除它本身和与它关联的多方的多个对象
delete-orphan，若想清空set，则set中的n方对象在数据库中被删除
save-update，若只save 1的一方，则与之相关联的n的对象会被保存
-->
<!-- order-by="ORDER_ID DESC" 查询set中元素时按id降序排 -->
<set name="set" table="ORDERS" inverse="true" cascade="save-update" order-by="ORDER_ID DESC" >
<key>
<column name="CUSTOMER_ID" />
</key>
<one-to-many class="Order" />
</set>
</class>
</hibernate-mapping>
Order.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">
<!-- Generated 2017-2-19 16:01:24 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_shuangxiang_n21">
<class name="Order" table="ORDERS">
<id name="orderId" type="java.lang.Integer">
<column name="ORDER_ID" />
<generator class="native" />
</id>
<property name="orderDesc" type="text">
<column name="ORDER_DESC" />
</property>
<!-- name：为1方的属性名 -->
<many-to-one name="customer" class="Customer">
<column name="CUSTOMER_ID" />
</many-to-one>
</class>
</hibernate-mapping>
Test.java
package model_shuangxiang_n21;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class HibernateTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void testMany2OneSave() {
Customer customer = new Customer();
customer.setCustomerName("Ji");
Order order1 = new Order("AA", customer);
Order order2 = new Order("BB", customer);
customer.getSet().add(order1);
customer.getSet().add(order2);
//这种顺序三条insert,默认是两条update，因为此时customer也要添加关联，
//当set标签的属性inverse为true时就不用update，因为此时customer是被动方，无需主动添加关联
//若不设置则1方和n方都为主动方就都需要添加关联
session.save(customer);
session.save(order1);
session.save(order2);
//这种顺序显示三条insert，默认是3条update
// session.save(order1);
// session.save(customer);
// session.save(order2);
}
@Test
public void testMany2OneGet() {
Customer customer = (Customer) session.get(Customer.class, 1);//懒加载set
System.out.println(customer.getSet().getClass());//class org.hibernate.collection.internal.PersistentSet
}
@Test
public void testMany2OneUpdate(){
Order order = (Order) session.get(Order.class, 1);
order.getCustomer().setCustomerName("Fei");
}
@Test
public void testMany2OneDelete(){
Order order = new Order();
order.setOrderId(2);
session.delete(order);
Customer customer = new Customer();
customer.setCustomerId(1);
session.delete(customer);
//customer是orders中的外键，所以当orders表中有order与此customer关联，则删除customer会报异常；若无则可删除
}
@Test
public void testSetCascade(){
Customer customer = (Customer) session.get(Customer.class, 3);
// session.delete(customer);
Order order = (Order) session.get(Order.class, 4);
// session.delete(order);
order.setCustomer(customer);
// customer.getSet().clear();
}
@Test
public void testSetCascade2(){
Customer customer = new Customer();
customer.setCustomerName("Fei");
Order order1 = new Order("CC", customer);
Order order2 = new Order("DD", customer);
customer.getSet().add(order1);
customer.getSet().add(order2);
session.save(customer);
}
}
双向n2n
双向多对多，若想使中间表中多出一行，可以自定义一个中间表的类（implements Serializable），其中包含了两个多方表的主键，并且在hbm文件中将这两个外键联合声明成一个主键
<composite-id> <key-property name="student_id" column="student_id" type="int"></key-property> <key-property name="course_id" column="course_id" type="int"></key-property> </composite-id>
He.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">
<!-- Generated 2017-2-21 17:15:59 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="model_shuangxiang_n2n.He" table="HES">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<set name="set" table="HE_YU">
<key>
<column name="H_ID" />
</key>
<many-to-many column="Y_ID" class="model_shuangxiang_n2n.Yu"></many-to-many>
</set>
</class>
</hibernate-mapping>
Yu.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">
<!-- Generated 2017-2-21 17:15:59 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="model_shuangxiang_n2n.Yu" table="YUS">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<!-- 重点inverse必须有一个 -->
<!-- table：为额外增加的一个联系表的名字 -->
<!-- key中列名是本表的主键在额外表中对应的外键列名 -->
<!-- many-to-many中列名为对应的对象的主键在额外表中对应的外键列名 -->
<set name="set" table="HE_YU" inverse="true">
<key>
<column name="Y_ID"></column>
</key>
<many-to-many column="H_ID" class="model_shuangxiang_n2n.He"></many-to-many>
</set>
</class>
</hibernate-mapping>
Test.java
package model_shuangxiang_n2n;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class Test_shuangxiang_n2n {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void testSave() {
Yu yu1 = new Yu();
Yu yu2 = new Yu();
He he1 = new He();
He he2 = new He();
yu1.setName("yun1");
yu2.setName("yun2");
he1.setName("ji1");
he2.setName("ji2");
he1.getSet().add(yu1);
he1.getSet().add(yu2);
he2.getSet().add(yu1);
yu1.getSet().add(he1);
yu1.getSet().add(he2);
yu2.getSet().add(he1);
session.save(he1);
session.save(he2);
session.save(yu1);
session.save(yu2);
//无update，只有7条insert
}
@Test
public void testGet(){
He he = (He) session.get(He.class, 5);
System.out.println(he.getName());
System.out.println(he.getSet().size());
}
@Test
public void testGet2(){
Yu yu = (Yu) session.get(Yu.class, 6);
System.out.println(yu.getSet().size());
}
}
双向121
外键方式
Nan.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"> <!-- Generated 2017-2-20 19:40:30 by Hibernate Tools 3.4.0.CR1 --> <hibernate-mapping package="model_shuangxiang_waijian_121"> <class name="Nan" table="NANS"> <id name="nanId" type="java.lang.Integer"> <column name="NAN_ID" /> <generator class="native" /> </id> <property name="nanName" type="java.lang.String"> <column name="NAN_NAME" /> </property> <!-- 要实现基于外键的121，就至少要有一方中含有外键，并且把外键的一列设置为唯一即可--> <!-- name：外键对应的属性的名--> <!-- column：外键列的列名--> <!-- unique：将外键列设置为唯一，，因为要实现的是121--> <many-to-one name="XiHuan" column="XI_HUAN" unique="true"></many-to-one> </class> </hibernate-mapping>
Nv.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">
<!-- Generated 2017-2-20 19:40:30 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_shuangxiang_waijian_121">
<class name="Nv" table="NVS">
<id name="nvId" type="java.lang.Integer">
<column name="NV_ID" />
<generator class="native" />
</id>
<property name="nvName" type="java.lang.String">
<column name="NV_NAME" />
</property>
<!-- name：关联的对象在本类中的属性的名-->
<!-- class：关联对象的全类名-->
<!-- property：这是外键关联方式在实现121时必须设置的，值为 关联对象中记录本对象的属性名(若不写在get时会出错)-->
<!-- 若只写<one-to-one>而不写用外键的方式生成主键，则单在NVS中看不到关联的另一端1，
加上property-ref="XiHuan"则在做外链接love所存的表时
left outer join
NANS nan1_
on nv0_.NV_ID=nan1_.XI_HUAN
-->
<one-to-one name="love" class="Nan" property-ref="XiHuan"></one-to-one>
</class>
</hibernate-mapping>
Test.java
package model_shuangxiang_waijian_121;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class HibernateTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void test121Save(){
Nan nan = new Nan();
nan.setNanName("AA");
Nv nv = new Nv();
nv.setNvName("BB");
//1的一方可以不set，但“多”的一方（即对应表中含有外键的一方）必须set
nan.setXiHuan(nv);
// nv.setLove(nan);
session.save(nv);
session.save(nan);
}
@Test
public void test121Get(){
// Nan nan = (Nan) session.get(Nan.class, 3);
// System.out.println(nan.getNanName());
// System.out.println(nan.getXiHuan().getNvName());
Nv nv = (Nv) session.get(Nv.class, 3);
System.out.println(nv.getLove().getNanName());
}
}
主键方式
Nan.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"> <!-- Generated 2017-2-20 19:40:30 by Hibernate Tools 3.4.0.CR1 --> <hibernate-mapping package="model_shuangxiang_zhujian_121"> <class name="Nan" table="NANS"> <id name="nanId" type="java.lang.Integer"> <column name="NAN_ID" /> <!-- 使用外键的方式生成主键 --> <generator class="foreign"> <!-- property 指定用哪一个属性的主键作为自己的外键 --> <param name="property">XiHuan</param> </generator> </id> <property name="nanName" type="java.lang.String"> <column name="NAN_NAME" /> </property> <!-- 这个one-to-one中要带有constrained=true 表示在此表中生成外键约束--> <one-to-one name="XiHuan" class="Nv" constrained="true"></one-to-one> </class> </hibernate-mapping>
Nv.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">
<!-- Generated 2017-2-20 19:40:30 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_shuangxiang_zhujian_121">
<class name="Nv" table="NVS">
<id name="nvId" type="java.lang.Integer">
<column name="NV_ID" />
<generator class="native" />
</id>
<property name="nvName" type="java.lang.String">
<column name="NV_NAME" />
</property>
<one-to-one name="love" class="Nan"></one-to-one>
</class>
</hibernate-mapping>
Test.java
package model_shuangxiang_zhujian_121;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class HibernateTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
sessionFactory.close();
}
@Test
public void test121Save(){
Nan nan = new Nan();
nan.setNanName("Ji");
Nv nv = new Nv();
nv.setNvName("Yun");
//主键生成方式是参照关联对象的一方必须set，但另一方可以不set
nan.setXiHuan(nv);
// nv.setLove(nan);
//此时无论顺序都是先插女再插男，且不会有多余的update
session.save(nan);
session.save(nv);
}
@Test
public void test121Get(){
//两个select
// Nan nan = (Nan) session.get(Nan.class, 2);
// System.out.println(nan.getNanName());
// System.out.println(nan.getXiHuan().getNvName());
//一个select
/*
* Hibernate:
select
nv0_.NV_ID as NV_ID1_1_1_,
nv0_.NV_NAME as NV_NAME2_1_1_,
nan1_.NAN_ID as NAN_ID1_0_0_,
nan1_.NAN_NAME as NAN_NAME2_0_0_
from
NVS nv0_
left outer join
NANS nan1_
on nv0_.NV_ID=nan1_.NAN_ID
where
nv0_.NV_ID=?
* */
Nv nv = (Nv) session.get(Nv.class, 2);
System.out.println(nv.getLove().getNanName());
}
}
继承映射
subclass方式
Person.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">
<!-- Generated 2017-2-24 19:56:10 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="model_extends.Person" table="PERSONS" discriminator-value="PERSON">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<discriminator column="TYPE" type="string"></discriminator>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<subclass name="model_extends.Student" discriminator-value="STUDENT" >
<property name="grade" type="string" column="GRADE"></property>
</subclass>
</class>
</hibernate-mapping>
Test.java
package model_extends;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import model_extends_join.Person;
public class TestExtends {
private SessionFactory factory = null;
private Session session = null;
private Transaction transaction = null;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry registry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
.buildServiceRegistry();
factory = configuration.buildSessionFactory(registry);
session = factory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
factory.close();
}
/**
* 只生成一张表。会用一列type的标识列，
*
* 关键：子类独有的属性在表中不能设置非null约束
*
* */
@Test
public void testSave() {
// Person p =new Person();
// p.setName("jiyunfei");
//
// session.save(p);
Student s = new Student();
s.setGrade("Wu");
session.save(s);
}
@Test
public void testGet() {
Student s = (Student) session.get(Student.class, 2);
System.out.println(s.getGrade());
s.setName("AA");
Person p = (Person) session.get(Person.class, 2);
System.out.println(p.getName());
}
}
joined-subclass方式
Person.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">
<!-- Generated 2017-2-26 9:14:01 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_extends_join">
<class name="Person" table="PERSONS">
<id name="id" type="int">
<column name="ID" />
<generator class="native" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<joined-subclass name="Student" table="STUDENTS">
<key column="ID"></key>
<property name="grade" type="string" column="GRADE"></property>
</joined-subclass>
</class>
</hibernate-mapping>
Test.java
package model_extends_join;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import model_extends_join.Person;
public class TestExtends {
private SessionFactory factory = null;
private Session session = null;
private Transaction transaction = null;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry registry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
.buildServiceRegistry();
factory = configuration.buildSessionFactory(registry);
session = factory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
factory.close();
}
/**
* join方式的继承映射是生成两张表，Students表中有一个主键id是Persons表的外键
*
* 只有一个冗余项就是Students中的主键
* */
@Test
public void testSave() {
// Person p =new Person();
// p.setName("jiyunfei");
//
// session.save(p);
Student s = new Student();
s.setGrade("Wu");
session.save(s);
}
/**
* 若查询的是Student，则用内连接只查询
*
* 若查询的是Person，则用的左外链接查询
* */
@Test
public void testGet() {
// Student s = (Student) session.get(Student.class, 2);
// System.out.println(s.getGrade());
// s.setName("AA");
Person p = (Person) session.get(Person.class, 2);
System.out.println(p.getName());
System.out.println(((Student)p).getGrade());
}
}
union-subclass方式
Person.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">
<!-- Generated 2017-2-26 9:14:01 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping package="model_extends_union">
<class name="Person" table="PERSONS">
<id name="id" type="int">
<column name="ID" />
<generator class="hilo" />
</id>
<property name="name" type="java.lang.String">
<column name="NAME" />
</property>
<union-subclass name="Student" table="STUDENTS">
<property name="grade" column="GRADE" type="string"></property>
</union-subclass>
</class>
</hibernate-mapping>
Test.java
package model_extends_union;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class TestExtends {
private SessionFactory factory = null;
private Session session = null;
private Transaction transaction = null;
@Before
public void before(){
Configuration configuration = new Configuration().configure();
ServiceRegistry registry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
.buildServiceRegistry();
factory = configuration.buildSessionFactory(registry);
session = factory.openSession();
transaction = session.beginTransaction();
}
@After
public void after(){
transaction.commit();
session.close();
factory.close();
}
/**
* union方式的继承映射时生成两个独立的没有外键链接的表，会有冗余字段
* */
@Test
public void testSave() {
// Person p =new Person();
// p.setName("jiyunfei");
//
// session.save(p);
Student s = new Student();
s.setGrade("Wu");
s.setName("QQ");
session.save(s);
}
/**
* 若查询的是Student，则只从Students表查询
*
* 若查询的是Person，则用的是联合查询
* */
@Test
public void testGet() {
Student s = (Student) session.get(Student.class, 32768);
System.out.println(s.getGrade());
// s.setName("AA");
// Person p = (Person) session.get(Person.class, 32768);
//
// System.out.println(p.getName());
// System.out.println(((Student)p).getGrade());
}
}
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