If you want to use a Camel route, to pickup files, then something like this
from("file:inbox")
.convertBodyTo(Properties.class)
.log("The foo value is {${body[foo]}")
.log("The bar value is {${body[bar]}")
What we then need is a type converter from java.io.File -> java.util.Properties. Which we could add to camel-core out of the box.
I logged a ticket to add that type converter out of the box in Camel: https://issues.apache.org/jira/browse/CAMEL-7312