xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<beans>


	<bean id="customerD" class="cn.edu.uestc.dao.CustomerDaoImpl"/>
	<bean id="cusromerS" class="cn.edu.uestc.service.CustomerServiceImpl">
		<property name="dao">
			<ref bean="customerD" />
		</property>
	</bean>
	<bean id="customerC" class="cn.edu.uestc.controller.Customer">
		<property name="name">
			<value>xiaoming</value>
		</property>
		<property name="num">
			<value>123456</value>
		</property>
		<property name="service">
			<ref bean="cusromerS" />
		</property>
	</bean>
</beans>
 

報錯：org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 2 in XML document from class path resource [SpringDemo.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 8; cvc-elt.1: 找不到元素 'beans' 的宣告。
   ……
Caused by: org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 8; cvc-elt.1: 找不到元素 'beans' 的宣告。
   ……

修改：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd/spring-beans-2.0.dtd">
<beans>
......
</beans>