package com.src.hibernate; 
 
public class Animal { 
 
 //id号 
 private int id; 
 public int getId() { 
 return id; 
 } 
 public void setId(int id) { 
 this.id = id; 
 } 
 
 //名称 
 private String name; 
 public String getName() { 
 return name; 
 } 
 public void setName(String name) { 
 this.name = name; 
 } 
 
 //性别 
 private boolean sex; 
 public boolean isSex() { 
 return sex; 
 } 
 public void setSex(boolean sex) { 
 this.sex = sex; 
 } 
} 

package com.src.hibernate; 
public class Bird extends Animal { 
 
 //高度 
 private int height; 
 public int getHeight() { 
 return height; 
 } 
 public void setHeight(int height) { 
 this.height = height; 
 } 
 
} 
 
package com.src.hibernate; 
public class Pig extends Animal { 
 
 //重量 
 private int weight; 
 public int getWeight() { 
 return weight; 
 } 
 public void setWeight(int weight) { 
 this.weight = weight; 
 } 
} 

<?xml version="1.0"?> 
<!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.src.hibernate.Animal" table="t_animal"> 
 <id name="id"> 
 <generator class="native"/> 
 </id> 
 <!-- 加入鉴别标签，且必须放在id后面 --> 
 <discriminator column="type" /> 
 <property name="name"/> 
 <property name="sex" type="boolean"/> 
 
 <subclass name="com.src.hibernate.Pig" discriminator-value="P"> 
 <property name="weight"/> 
 </subclass> 
 <subclass name="com.src.hibernate.Bird" discriminator-value="B"> 
 <property name="height"/> 
 </subclass> 
 </class> 
 
</hibernate-mapping> 

public void testSave(){ 
 Session session=null; 
 try{ 
 //创建session对象 
 session=HibernateUtils.getSession(); 
 //开启事务 
 session.beginTransaction(); 
 
 Pig pig=new Pig(); 
 pig.setName("小猪猪"); 
 pig.setSex(true); 
 pig.setWeight(200); 
 session.save(pig); 
 
 Bird bird=new Bird(); 
 bird.setName("xiaoniaoniao"); 
 bird.setSex(true); 
 bird.setHeight(100); 
 session.save(bird); 
 
 session.getTransaction().commit(); 
 }catch(Exception e){ 
 e.printStackTrace(); 
 session.getTransaction().rollback(); 
 }finally{ 
 HibernateUtils.closeSession(session); 
 } 
 
} 

<?xml version="1.0"?> 
<!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.src.hibernate.Animal" table="t_animal" lazy="false"> 
 <id name="id"> 
 <generator class="native"/> 
 </id> 
 <!-- 加入鉴别标签，且必须放在id后面 --> 
 <discriminator column="type" /> 
 <property name="name"/> 
 <property name="sex" type="boolean"/> 
 
 <subclass name="com.src.hibernate.Pig" discriminator-value="P"> 
 <property name="weight"/> 
 </subclass> 
 <subclass name="com.src.hibernate.Bird" discriminator-value="B"> 
 <property name="height"/> 
 </subclass> 
 </class> 
</hibernate-mapping> 

public void testLoad(){ 
 Session session=null; 
 try{ 
 session=HibernateUtils.getSession(); 
 session.beginTransaction(); 
 
 Animal ani=(Animal)session.load(Animal.class,1); 
 System.out.println(ani.getName()); 
 //因为load默认支持lazy，所以我们看到的是Animal的代理 
 //所以采用了instanceof无法鉴别出真正的类型Pig 
 //所以load在此情况下是不支持多态查询的 
 if(ani instanceof Pig){ 
 System.out.println("我是小猪猪！"); 
 }else{ 
 System.out.println("我不是小猪猪！"); 
 } 
 session.getTransaction().commit(); 
 }catch(Exception e){ 
 e.printStackTrace(); 
 session.getTransaction().rollback(); 
 }finally{ 
 HibernateUtils.closeSession(session); 
 } 
} 

public void testLoad5(){ 
 Session session=null; 
 try{ 
 session=HibernateUtils.getSession(); 
 session.beginTransaction(); 
 
 List<Animal> list=session.createQuery("from Animal").list(); 
 for(Iterator iter=list.iterator();iter.hasNext();){ 
 Animal a=(Animal)iter.next(); 
 if(a instanceof Pig){ 
 System.out.println("我是小猪猪！"); 
 }else{ 
 System.out.println("我不是小猪猪！"); 
 } 
 } 
 session.getTransaction().commit(); 
 }catch(Exception e){ 
 e.printStackTrace(); 
 session.getTransaction().rollback(); 
 }finally{ 
 HibernateUtils.closeSession(session); 
 } 
} 

Hibernate: select animal0_.id as id0_, animal0_.name as name0_, animal0_.sex as sex0_, animal0_.weight as weight0_, animal0_.height as height0_, animal0_.type as type0_ from t_animal animal0_ 
我是小猪猪！ 
我不是小猪猪！ 
我是小猪猪！ 
我不是小猪猪！ 

<class name="Payment" table="PAYMENT"> 
 <id name="id" type="long" column="PAYMENT_ID"> 
 <generator class="native"/> 
 </id> 
 <discriminator column="PAYMENT_TYPE" type="string"/> 
 <property name="amount" column="AMOUNT"/> 
 ... 
 <subclass name="CreditCardPayment" discriminator-value="CREDIT"> 
 <property name="creditCardType" column="CCTYPE"/> 
 ... 
 </subclass> 
 <subclass name="CashPayment" discriminator-value="CASH"> 
 ... 
 </subclass> 
 <subclass name="ChequePayment" discriminator-value="CHEQUE"> 
 ... 
 </subclass> 
</class> 

<class name="Payment" table="PAYMENT"> 
 <id name="id" type="long" column="PAYMENT_ID"> 
 <generator class="native"/> 
 </id> 
 <property name="amount" column="AMOUNT"/> 
 ... 
 <joined-subclass name="CreditCardPayment" table="CREDIT_PAYMENT"> 
 <key column="PAYMENT_ID"/> 
 ... 
 </joined-subclass> 
 <joined-subclass name="CashPayment" table="CASH_PAYMENT"> 
 <key column="PAYMENT_ID"/> 
 <property name="creditCardType" column="CCTYPE"/> 
 ... 
 </joined-subclass> 
 <joined-subclass name="ChequePayment" table="CHEQUE_PAYMENT"> 
 <key column="PAYMENT_ID"/> 
 ... 
 </joined-subclass> 
</class> 

<class name="Payment" table="PAYMENT"> 
 <id name="id" type="long" column="PAYMENT_ID"> 
 <generator class="native"/> 
 </id> 
 <discriminator column="PAYMENT_TYPE" type="string"/> 
 <property name="amount" column="AMOUNT"/> 
 ... 
 <subclass name="CreditCardPayment" discriminator-value="CREDIT"> 
 <join table="CREDIT_PAYMENT"> 
 <property name="creditCardType" column="CCTYPE"/> 
 ... 
 </join> 
 </subclass> 
 <subclass name="CashPayment" discriminator-value="CASH"> 
 <join table="CASH_PAYMENT"> 
 ... 
 </join> 
 </subclass> 
 <subclass name="ChequePayment" discriminator-value="CHEQUE"> 
 <join table="CHEQUE_PAYMENT" fetch="select"> 
 ... 
 </join> 
 </subclass> 
</class>