import java.io.File;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

public class TestAddUrl {

 public static void main(String[] args) throws Exception {
 URLClassLoader classLoader = (URLClassLoader) TestAddUrl.class.getClassLoader();
 String dir = "/Users/kimmking/Downloads/Hello";
 Method method = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
 method.setAccessible(true);
 method.invoke(classLoader, new File(dir).toURL());

 Class klass = Class.forName("Hello",true, classLoader);
 Object obj = klass.newInstance();
 Method hello = klass.getDeclaredMethod("hello");
 hello.invoke(obj);
 }

}