jquery数据表排序图标放在实际文本下面的行？

$(document).ready(function() {
    $('#example').DataTable( {
        "order": [[ 0, "asc" ]],
        "columnDefs": [
            { "orderable": false, "targets": 1 }
        ],
        "language": {
            "info": "显示 _START_ 到 _END_ 共有 _TOTAL_ 条数据",
            "infoEmpty": "显示 0 到 0 共有 0 条数据",
            "infoFiltered": "(从 _MAX_ 条数据中检索)",
            "paginate": {
                "first": "首页",
                "last": "尾页",
                "next": "下一页",
                "previous": "上一页"
            },
            "search": "搜索:",
            "lengthMenu": "每页显示 _MENU_ 条数据",
            "zeroRecords": "没有找到符合条件的数据",
            "emptyTable": "表格中无数据",
            "loadingRecords": "加载中...",
            "processing": "处理中...",
            "sortAscending": "升序排序",
            "sortDescending": "降序排序",
            "sortable": "可排序",
            "unsortable": "不可排序"
        }
    } );
} );

   <thead>
        <tr>
            <th>列1</th>
            <th>列2</th>
        </tr>
    </thead>
   <tbody>
        <tr>
            <td>数据1</td>
            <td>数据2</td>
        </tr>
        <tr>
            <td>数据3</td>
            <td>数据4</td>
        </tr>
    </tbody>
</table>