mybatis如何实现继承映射

package com.tgb.mybatis.model; 
public class Vehicle {
	//主键id
	private String id;
	//车的名字
	private String name;
	
	public String getId() {
		return id;
	}
	
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	} 
}

package com.tgb.mybatis.model; 
public class Car extends Vehicle {
	//车门的数量
	private int carDoor;
	//车的牌子
	private String band;
	
	public int getCarDoor() {
		return carDoor;
	}
	public void setCarDoor(int carDoor) {
		this.carDoor = carDoor;
	}
	public String getBand() {
		return band;
	}
	public void setBand(String band) {
		this.band = band;
	}	
}

package com.tgb.mybatis.model; 
public class Bus extends Vehicle {
	//公共汽车的容量
	private int capacity;
 
	public int getCapacity() {
		return capacity;
	} 
	public void setCapacity(int capacity) {
		this.capacity = capacity;
	}	
}

package com.tgb.mybatis.data; 
import com.tgb.mybatis.model.Bus;
import com.tgb.mybatis.model.Car;
import com.tgb.mybatis.model.Vehicle; 
public interface VehicleMapper {
	//根据id查询机动车
	Vehicle getVechicleById(String id);
	//根据名字查询小汽车
	Car getCarByName(String name);
}

<?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
<mapper namespace="com.tgb.mybatis.data.VehicleMapper">
    <select id="getVechicleById" resultMap="vehicleMap">
        SELECT * FROM TB_VEHICLE WHERE VID = #{id}
    </select>
    <select id="getCarByName" resultMap="vehicleMap">
        SELECT * FROM TB_VEHICLE WHERE VTYPE='c' AND VName = #{id}
    </select>
   <resultMap type="vehicle" id="vehicleMap">
       <id property="id" column="vId"/>
       <result property="name" column="vName"/>
       <discriminator javaType="string" column="vType">
           <case value="c" resultType="car">
               <result property="carDoor" column="cardoor"/>
               <result property="band" column="band"/>
           </case>
           <case value="b" resultType="bus">
               <result property="capacity" column="capacity"/>
           </case>
       </discriminator>
   </resultMap>
</mapper>

VehicleMapper mapper = session.getMapper(VehicleMapper.class);
Vehicle vehicle = mapper.getVechicleById("1");
System.out.println(vehicle.getName());
Car car = mapper.getCarByName("路虎007");
System.out.println(car.getBand());

public interface TagMapper {
    /**
     * This method was generated by MyBatis Generator.
     * This method corresponds to the database table t_tag
     *
     * @mbg.generated
     */
    long countByExample(TagExample example);
    /**
     * This method was generated by MyBatis Generator.
     * This method corresponds to the database table t_tag
     *
     * @mbg.generated
     */
    int deleteByExample(TagExample example);
}

public interface TagExtendMapper extends TagMapper {
    ...
}

<mapper namespace="com.xxx.dao.mapper.TagMapper">
  <resultMap id="BaseResultMap" type="com.xxx.dao.Tag">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
    -->
    <id column="id" jdbcType="CHAR" property="id" />
    <result column="tag_name" jdbcType="VARCHAR" property="tagName" />
    <result column="tag_alias" jdbcType="VARCHAR" property="tagAlias" />
  </resultMap>
</mapper>

<mapper namespace="com.xxx.dao.TagExtendMapper">
    <select id="xxxxx" resultMap="com.xxx.dao.mapper.TagMapper.BaseResultMap"> <!-- 这里时原始命名空间加上结果集id -->
    </select>
</mapper>

<mapper namespace="com.xxx.dao.TagExtendMapper">
   <resultMap id="ExtBaseResultMap" type="com.xxx.dao.Tag" extend="com.xxx.dao.mapper.TagMapper.BaseResultMap">
       ...
  </resultMap>
</mapper>