Thus, on the way to classes. You can just use ClassLoader#getResourceAsStream()to get InputStream. Assuming what srcis the root of the classpath and what main/resourcesis the package:
InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream("main/resources/foo.properties");
Properties properties = new Properties();
properties.load(input);
, webapp , , , (, appserver lib JRE lib), ExternalContext#getResourceAsStream().
InputStream input = FacesContext.getCurrentInstance().getExternalContext().getResourceAsStream("main/resources/foo.properties");
Properties properties = new Properties();
properties.load(input);
#{resource}, CSS/JS/image, /resources -. . CSS/JS/image Facelets?