效果
<body>
<div class="container">
<div class="dropdown col-sm-3 col-sm-offset-2">
<button type="button" class="btn btn-danger" data-toggle="dropdown" >
<span class="glyphicon glyphicon-user"></span>
用户
<span class="caret"></span>
</button>
<ul class="dropdown-menu dropdown-menu-left">
<li class="dropdown-header">文件管理</li>
<li class="active"><a href="#">
<span class="glyphicon glyphicon-off"></span>
文件</a></li>
<li class="disabled"><a href="#">Disabled link</a></li>
<li><a href="#">文件</a></li>
<li class="divider"></li>
<li><a href="#">文件</a></li>
</ul>
</div>
</div>
</body>
