ResourceCataloguer.java

package fi.markoa.proto.libload;

import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;


public class ResourceCataloguer {
  private enum Protocol { JAR, FILE }

  public List<String> listResourceDirectory(String dir) {
    URL u = this.getClass().getResource("/"+dir);
    Protocol protocol = Protocol.valueOf(u.getProtocol().toUpperCase());
    List<String> res = new ArrayList<String>();
    switch (protocol) {
      case JAR:
        try {
          JarURLConnection juc = (JarURLConnection)u.openConnection();
          for (Enumeration<JarEntry> en = juc.getJarFile().entries(); en.hasMoreElements(); ) {
            JarEntry je = en.nextElement();
            if(!je.isDirectory() && je.getName().startsWith(dir+"/")) {
              res.add("/"+je.getName());
            }
          }
        } catch (IOException ex) {
          throw new RuntimeException("failed to open jar file: "+u, ex);
        }
        break;
      case FILE:
        for(File f : (new File(u.getFile())).listFiles()) { // only top-level directory
          res.add(String.format("/%s/%s", dir, f.getName()));
        }
        break;
      default:
        throw new RuntimeException(String.format("unsupported protocol: %s, %s", protocol, u));
    }
    return res;
  }

  public static void main(String ... args) throws Exception {
    ResourceCataloguer m = new ResourceCataloguer();
    for(String f : m.listResourceDirectory("lib")) {
      System.out.println("res: "+f+", "+m.getClass().getResource(f));
    }
  }

}