“Could not format discriminator value to SQL string...”错误的解决方法

继承映射关系中如果映射到一张表中，则父类子类都必须加上discriminator-value属性，否则会报此错误，另：discriminator-value类型默认是String类型的；

<?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 package="com.xx.domain">
	<!-- 继承关系之映射成一张表 -->
	<!-- 父类的也必须加上discriminator-value属性 -->
	<class name="Animal" table="t_animal" discriminator-value="0">
		<id name="id">
			<generator class="native" />
		</id>
		<discriminator column="type" type="int"/>
		<property name="name" not-null="true" />
		<subclass name="Pepole" discriminator-value="1">
			<property name="sex" ></property>
		</subclass>
		<subclass name="Dog" discriminator-value="2">
			<property name="age" ></property>
		</subclass>
	</class>

</hibernate-mapping>