public static <T>T newInstance(Class<T> interfaceClass){
            try {
                //    
                //  UserDao.class
                String name = interfaceClass.getSimpleName();

                //   
                String className=findClassNameByName(name);

                //
                Class<?> aClass = Class.forName(className);

                Object o = aClass.newInstance();
                return (T) o;
            } catch (Exception e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }

        private static String findClassNameByName(String name) throws DocumentException {
            //
            SAXReader saxReader = new SAXReader();

            //
            InputStream in = BeanFactory.class.getClassLoader().getResourceAsStream("beans.xml");
            //doc
            Document document = saxReader.read(in);
            //xpath 
            Element element = (Element) document.selectSingleNode("//bean[@id="" + name + ""]");

            //
            return element.attributeValue("class");
        }