how to use external config file with Spring MVC

I am using Spring MVC framework to develop my Java Web application.
I put a config.properties under src/main/resources.

a=1
c=2

Select allOpen in new window

In my Spring MVC controller, I use code like below to retrieve the config value.

                        InputStream inputStream = getClass().getClassLoader().getResourceAsStream(propFileName);
			if(null != inputStream) {
				prop.load(inputStream);
			} else {
				throw new FileNotFoundException("property file not found in the classpath");
			}
			
			a = prop.getProperty("a");
			b = prop.getProperty("b");

Select allOpen in new window

And then I packaged the project with "mvn clean package" and deployed the war into Tomcat's webapps folder.

However, with this approach, my config.properties is packaged into the war and it is hard to change.

So would some one please provide a way to solve this problem? Can I use spring to read external config file? Please note that I need to read the config file every time the controller method is called instead of loading it when spring starts. Thanks!