code: public void setExecutor(DaoExecutor executor) {
          this.executor = executor;
          if (executor instanceof NutDaoExecutor) {
          	((NutDaoExecutor)executor).setMeta(meta);
          	((NutDaoExecutor)executor).setExpert(expert);
          }
      }
docs: 设置一个新的 Dao 语句执行器
  
  @param executor
  Dao 语句执行器对象