jasperDesign.setScriptletClass("Scriptlet");

File root = new File("/home/am/Desktop");

    Class<?> cls = null;
    try {
        URLClassLoader classLoader = URLClassLoader.newInstance(
                new URL[] { root.toURI().toURL() },
                GenerateReport.class.getClassLoader());
        cls = Class.forName("Scriptlet", true, classLoader);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }