用properties文件读取数据库的配置文件

当properties文件在src目录下时！！！以下三种路径都是正确的。（经过实验验证都可以读到配置文件），classpath不需要大写字母
<bean id="property"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <value>classpath:jdbc.properties</value>
        </property>
    </bean>

<bean id="property"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <value>jdbc.properties</value>
        </property>
    </bean>

<bean id="property"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <value>/jdbc.properties</value>
        </property>
    </bean>

 Ｓｐｒｉｎｇ中读取配置文件ｐｒｏｐｅｒｔｉｅｓ

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