Reading properties from a path defined in system property with a default value.

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans>
    <bean id="applicationConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:app-dev.properties</value>
                <value>${app.properties}</value>
            </list>
        </property>
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="true"/>
    </bean>
</beans>