docs: public static Class getSuperClassGenericType(Class clazz, int index) {
          Type genType = clazz.getGenericSuperclass();//得到泛型父类  
          //如果没有实现ParameterizedType接口，即不支持泛型，直接返回Object.class
  
          if (!(genType instanceof ParameterizedType)) {
              return Object.class;   
          }  
          //返回表示此类型实际类型参数的Type对象的数组,数组里放的都是对应类型的Class, 如BuyerServiceBean extends DaoSupport<Buyer,Contact>就返回Buyer和Contact类型   
          Type[] params = ((ParameterizedType) genType).getActualTypeArguments();                   
          if (index >= params.length || index < 0) { 
          	 throw new IllegalArgumentException("index "+ (index<0 ? " must > 0 " : " over total arguments"));
          }      
          if (!(params[index] instanceof Class)) {
              return Object.class;   
          }   
          return (Class) params[index];
      }