Clojure list subfolders in resources in uberjar

Question

I have a folder structure like this:

• resources
  • a
    • b
      • x.txt
    • c
      • x.txt

I've created my runnable jar with lein uberjar.

When running my jar, I want to list the subfolders of a.

I know I can get the contents of resources/a/b/x.txt using clojure.java.io

(slurp (clojure.java.io/resource "a/b/x.txt"))

But I can't find a simple way to list the subfolders.

(clojure.java.io/file (clojure.java.io/resource "a")) just results in a java.lang.IllegalArgumentException: Not a file because it isn't a file, it's a resource inside the jar file.

Is there a library that does this?

Answer 1

A different approach (but I must admit that it doesn't feel entirely satisfactory) is to read the contents at compile time. Assuming you have a function list-files that gives you the list from your project root directory:

(defmacro compile-time-filelist []
  `'~(list-files "resources/a"))

or

(defmacro compile-time-filelist []
  (vec (list-files "resources/a")))

Answer 2

You can recursively list all items in a dir using file-seq function. Example:

(let [files (file-seq (clojure.java.io/file "resources"))
      dir? #(.isDirectory %)]
  (map dir? files))

You can also call .listFiles or .list on a File object. The first gives file objects, the second gives filenames.

You can find additional examples here and here.