Java Code To Grab All Files Located Under A Folder

I am currently using the following Rally API Java code(below...in Java 1.7) to create an object and attach a file to it. This code works fine. But I need the code to be a little less specific and attach all files located under a folder (not just one file). How could one potentially rewrite this code (or use a different constructor/method) to accommodate such a thing? Also additional code how to narrow down results to all files with a creation date >= today.

Java Code:

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.rallydev.rest.RallyRestApi;
import com.rallydev.rest.request.CreateRequest;
import com.rallydev.rest.request.DeleteRequest;
import com.rallydev.rest.request.GetRequest;

[Code] ....