html的table列表根据奇数还是偶数行显示不同颜色

<tr <s:if test="#sts.even"> class="table_1" onMouseOut="this.className='table_1'" onMouseOver="this.className='tab_over'"</s:if><s:else> class="table_2" onMouseOut="this.className='table_2'" onMouseOver="this.className='tab_over'"</s:else>>