Spring 配置中的 ${}

    <!-- ============ GENERAL DEFINITIONS========== -->

<!-- Configurer that replaces ${...} placeholders with values from a properties file -->

<!-- (in this case, JDBC-related settings for the dataSource definition below) -->

<bean id="propertyConfigurer"

class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<property name="location">

<value>classpath:spring/jdbc-oracle.properties</value>

</property>

</bean>

<!-- =========== RESOURCE DEFINITIONS ============ -->

<!-- Local DataSource that works in any environment -->

<bean id="dataSource"

class="org.springframework.jdbc.datasource.DriverManagerDataSource">

<property name="driverClassName">

<value>${jdbc.driverClassName}</value>

</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>

当jdbc-oracle.properties文件加载下后，${}即可取出其中的内容