making environment specific property files in spring mvc

HI,
I am having following project structure :
resources->properties ->[database.properties, log4j.properties]
I want to create a new project structure in which inside the properties folder there will be following folders
DEV
PROD
QA
each having there own database.properties and log4j.properties file.

I am using maven with spring mvc. How do i make this possible so that when i build the project the right property file gets picked up based on the system environment variables.
eg. if the system environment variable env = DEV then properties files under the dev folder should be used.

Thanks