类表继承

package com.jzq.hibernate;

public class Animal {

 private int id;
 private String name;
 private String sex;
 public Animal(){}
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return n

}

}

bird类：

package com.jzq.hibernate;

public class Bird extends Animal {

   private int height;
   public Bird(){}
   public int getHeight() {
 return height;
   }
 public void setHeight(int height) {
  this.height = height;
 }

}

Pig类：

package com.jzq.hibernate;

public class Pig extends Animal {

 private int height;
 public int getHeight() {
  return height;
 }
 public void setHeight(int height) {
  this.height = height;
 }
 public Pig(){}
}

配置文件：

<!-- 每个具体类映射成一张表，其中Animal表位抽象空表  -->
<hibernate-mapping>
   <class name="Animal" package="com.jzq.hibernate">
      <id name="id">
          <generator class="assigned"/>
      </id>
      <property name="name"/>
      <property name="sex"/>
     
      <!--
                            
                              连接子类 Pig
           表中的字段：id，name，sex，weight 
      -->
      <union-subclass name="Pig" table="t_pig">
          <property name="weight"/>
      </union-subclass>
     
      <!--
                            连接子类 Bird
          表中的字段：id，name，sex，height
      -->
       <union-subclass name="Bird" table="t_bird">
          <property name="height"/>
      </union-subclass>
     
   </class>
</hibernate-mapping>

在代码程序中要手动分配键值