gistfile1.java

ClassLoader cl = new SecureClassLoader() {

   @Override
   protected URL findResource(final String name) {
      final Asset a = archive.get(name);
      if (a == null) {
         return null;
      }
      try {
         return new URL(null, "archive:/" + name, new URLStreamHandler() {

            @Override
            protected java.net.URLConnection openConnection(URL u) throws java.io.IOException {
               return new URLConnection(u) {

                  @Override
                  public void connect() throws IOException {
                  }

                  @Override
                  public InputStream getInputStream()
                          throws IOException {
                     return a.openStream();
                  }
               };
            }

            ;
         });
      } catch (Exception e) {
         return null;
      }
   }

   @Override
   protected Enumeration<URL> findResources(String name) throws IOException {
      Iterator<URL> it = new ArrayList<URL>(0).iterator();
      URL resource = findResource(name);
      if (resource != null) {
         it = Arrays.asList(resource).iterator();
      }
      final Iterator<URL> i = it;
      return new Enumeration<URL>() {

         @Override
         public boolean hasMoreElements() {
            return i.hasNext();
         }

         @Override
         public URL nextElement() {
            return i.next();
         }
      };
   }
};

Thread.currentThread().setContextClassLoader(cl);