一：直接使用context命名空间

如：

<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"
	xmlns:websocket="http://www.springframework.org/schema/websocket"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
	   http://www.springframework.org/schema/beans/spring-beans.xsd
	   http://www.springframework.org/schema/websocket
       http://www.springframework.org/schema/websocket/spring-websocket.xsd
	   http://www.springframework.org/schema/context 
	   http://www.springframework.org/schema/context/spring-context.xsd">

<context:property-placeholder location="classpath:log4j.properties" />

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
	<property name="locations" value="http://www.mamicode.com/classpath:jdbc.properties" />
</bean>

<property name="url" value="http://www.mamicode.com/${jdbc.url}"/>