spring的自生一个bug

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context.xsd">

   <!-- 注册数据源：Spring内置数据源 -->
   <!-- 
   <bean id="myDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
           <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
           <property name="url" value="jdbc:mysql://127.0.0.1:3366/test"/>
           <property name="username" value="root"/>
           <property name="password" value="111"/>
   </bean>
    -->
   <!-- 注册数据源：DBCP -->
   <!-- 
   <bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource">
           <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
           <property name="url" value="jdbc:mysql://127.0.0.1:3366/test"/>
           <property name="username" value="root"/>
           <property name="password" value="111"/>
   </bean>
    -->
   <!-- 注册数据源：C3P0 -->
   <!-- 
   <bean id="myDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
           <property name="driverClass" value="com.mysql.jdbc.Driver"/>
           <property name="jdbcUrl" value="jdbc:mysql://127.0.0.1:3366/test"/>
           <property name="user" value="root"/>
           <property name="password" value="111"/>
   </bean>
    -->
   <!-- 注册数据源：C3P0 -->
   <bean id="myDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
           <property name="driverClass" value="${jdbc.driver}"/>
           <property name="jdbcUrl" value="${jdbc.url}"/>
           <property name="user" value="${jdbc.user}"/>
           <property name="password" value="${jdbc.password}"/>
   </bean>
   
   <!-- 注册属性文件：方式一 -->
   <!-- 
   <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
           <property name="location" value="classpath:jdbc.properties"/>
   </bean>
    -->
   <!-- 注册属性文件：方式二 -->
   <context:property-placeholder location="classpath:jdbc.properties"/>
   
   <!-- 注册Jdbc模板对象 -->
   <!-- 
   <bean id="myJdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
           <property name="dataSource" ref="myDataSource"/>
   </bean>
   <bean id="studentDao" class="com.bjpowernode.dao.StudentDaoImpl">
           <property name="jdbcTemplate" ref="myJdbcTemplate"/>
   </bean>
    -->
   <!-- 注册Dao -->
   <bean id="studentDao" class="com.bjpowernode.dao.StudentDaoImpl">
           <property name="dataSource" ref="myDataSource"/>
   </bean>
   
   <!-- 注册Service -->
   <bean id="studentService" class="com.bjpowernode.service.StudentServiceImpl">
           <property name="dao" ref="studentDao"/> //如果是动态代理生成dao实现类，这里注入使用接口，一般接口IStudentDao以I开头，如果是StudentDao命名的接口，这里的studentDao首字母是小写s
   </bean>