Added getDirectoryContents

src/dorkbox/util/LocationResolver.java

@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.net.URLDecoder;
@@ -31,8 +32,12 @@ import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Enumeration;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.Vector;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
 import java.util.regex.Pattern;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipInputStream;
@@ -333,6 +338,64 @@ class LocationResolver {
         }
     }
 
+    /**
+     * List directory contents for a resource folder. Not recursive.
+     * This is basically a brute-force implementation.
+     * Works for regular files and also JARs.
+     *
+     * @author Greg Briggs
+     * @param clazz Any java class that lives in the same place as the resources you want.
+     * @param path Should end with "/", but not start with one.
+     * @return Just the name of each member item, not the full paths.
+     *
+     *
+     * @throws URISyntaxException
+     * @throws IOException
+     */
+    String[] getDirectoryContents(Class clazz, String path) throws URISyntaxException, IOException {
+        URL dirURL = clazz.getClassLoader().getResource(path);
+        if (dirURL != null && dirURL.getProtocol().equals("file")) {
+            /* A file path: easy enough */
+            return new File(dirURL.toURI()).list();
+        }
+
+        if (dirURL == null) {
+            /*
+             * In case of a jar file, we can't actually find a directory.
+             * Have to assume the same jar as clazz.
+             */
+            String me = clazz.getName().replace(".", "/") + ".class";
+            dirURL = clazz.getClassLoader().getResource(me);
+        }
+
+        if (dirURL.getProtocol()
+                  .equals("jar")) {
+            /* A JAR path */
+            String jarPath = dirURL.getPath().substring(5, dirURL.getPath().indexOf("!")); //strip out only the JAR file
+
+            JarFile jar = new JarFile(URLDecoder.decode(jarPath, "UTF-8"));
+            Enumeration<JarEntry> entries = jar.entries(); //gives ALL entries in jar
+            Set<String> result = new HashSet<String>(); //avoid duplicates in case it is a subdirectory
+
+            while (entries.hasMoreElements()) {
+                String name = entries.nextElement().getName();
+                if (name.startsWith(path)) { //filter according to the path
+                    String entry = name.substring(path.length());
+                    int checkSubdir = entry.indexOf("/");
+                    if (checkSubdir >= 0) {
+                        // if it is a subdirectory, we just return the directory name
+                        entry = entry.substring(0, checkSubdir);
+                    }
+                    result.add(entry);
+                }
+            }
+            return result.toArray(new String[result.size()]);
+        }
+
+        throw new UnsupportedOperationException("Cannot list files for URL " + dirURL);
+    }
+
+
     @SuppressWarnings("Duplicates")
     private static
     class Root {