spring的xml中引入单个配置文件
<context:property-placeholder location="classpath:release/jdbc.properties" />
spring的xml中引入多个配置文件(需要加ignore-unresolvable="true")
//模糊匹配
<context:property-placeholder location="classpath:release/*.properties" ignore-unresolvable="true"/>
//精准匹配
<context:property-placeholder location="classpath:release/jdbc.properties,classpath:release/config.properties,classpath:release/ireport.properties" ignore-unresolvable="true"/>
需要注意的是context:property-placeholder标签只能出现一次，所以如果在xml中配置多个context:property-placeholder，spring默认只识别第一个
