幕布斯7574896
可以啊，你在对应的li上类名active即可。<div class="dropdown">
<button type="button" class="btn dropdown-toggle" id="dropdownMenu1"
data-toggle="dropdown">
主题
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
<li class="active" role="presentation">
<a role="menuitem" tabindex="-1" href="#">Java</a>
</li>
<li role="presentation">
<a role="menuitem" tabindex="-1" href="#">数据挖掘</a>
</li>
<li role="presentation">
<a role="menuitem" tabindex="-1" href="#">数据通信/网络</a>
</li>
<li role="presentation" class="divider"></li>
<li role="presentation">
<a role="menuitem" tabindex="-1" href="#">分离的链接</a>
</li>
</ul>
</div>