下拉菜單必要的代碼：

<div class="container">

<div class="dropdown">

<button class="btn btn-default dropdown-toggle" id="aa" data-toggle="dropdown" aria-expanded="true">

按鈕</button>

<ul class="dropdown-menu" role="menu" aria-labelledby="aa">

<li><a href="">菜單1</a></li>

<li><a href="">菜單2</a></li>

</ul>

</div>

</div>

可在下拉列表中插入的內容有：a,分割線：<span class="glyphicon glyphicon-xxx" aria-hidden="true"></span>

b,提示信息：<li role="presentation" class="divider"></li>

c,默認不能點擊：<li role="presentation" class="disabled"><a href="jarascript:voidco">xx</a></li>

bootstrap中的下拉菜單