Reading Properties File From Resources Folder

In my java app there is a code which reads the properties file from src/main/resources folder.

Java Code:

@Component("mailerProperties")
public class MailerProperties {
private static Properties properties;
public MailerProperties() {
properties = new Properties();

[Code] ....

Now I need to create a jar file and also remove the properties file from src/main/resources folder and place it outside the jar file(in the same location as jar file) so that data inside it can be changed easily in future.

Question: Currently it uses ClassPathResource("mailer.properties") to read the prop file. What change I need to make to read it from outside the jar file...