Widget _sortableTable(BuildContext context) {
    return TDTable(
      columns: [
        TDTableCol(title: '标题', colKey: 'title1', ellipsis: true, sortable: true),
        TDTableCol(title: '标题', colKey: 'title2', sortable: true),
        TDTableCol(title: '标题', colKey: 'title3', sortable: true),
        TDTableCol(title: '标题', colKey: 'title4', sortable: true)
      ],
      data: _getData(9),
    );
  }