code: public Serializable getFieldValue(Attribute<T, Serializable> attr, T entity) {
          Serializable val = attr.get(entity);
          CryptHandler cryptHandler = attr.attach();
          if (cryptHandler != null) val = (Serializable) cryptHandler.decrypt(val);
          return val;
      }
docs: 数据库的值转换成数字段值
  
  @param attr   Attribute
  @param entity 记录对象
  
  @return Object