spring properties的引入

<bean id="propertyConfigurer"     
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">      
    <property name="location" value="/WEB-INF/jdbc.properties"/>  
    <!--
    <property name="location" value="classpath*:data.properties"/>
    -->   
</bean>      
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"       
        destroy-method="close">      
    <property name="driverClassName" value="${jdbc.driverClassName}" />      
    <property name="url" value="${jdbc.url}" />      
    <property name="username" value="${jdbc.username}" />      
    <property name="password" value="${jdbc.password}" />      
</bean>