Spring allows to externalize string literals in its context configuration files into external properties files, in order to separate application specific settings from framework specific configuration.

<context:property-placeholder/>

This element activates the replacement of ${…} placeholders, resolved against the specified properties file (as a Spring resource location).

<context:property-placeholder
    location = "classpath:dao.properties,
                classpath:services.properties,
                classpath:user.properties,
                /WEB-INF/config/config.properties"
    ignore-unresolvable="true"/>

PropertyPlaceholderConfigurer

A property resource configurer that resolves placeholders in bean property values of context definitions.

<bean
    id="propertyConfigurer"
    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
 
    <property name="locations">
        <list>
            <value>classpath:dao.properties</value>
            <value>classpath:services.properties</value>
            <value>classpath:user.properties</value>
            <value>/WEB-INF/config/config.properties</value>
        </list>
    </property>
 
    <property name="ignoreUnresolvablePlaceholders" value="true"/>
</bean>