data-dismiss 用法

<div class="col-md-12">
<div class="alert alert-danger alert-dismissible fade in" role="alert">
<button class="close" type="button" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">*</span>
</button>
<h4>网站程序有漏洞，急需修复！</h4>
<p>当前版本程序(V1.22)存在严重安全问题，容易造成攻击，请即可修复！</p>
<p>
<button class="btn btn-danger">立即修复</button>
<button class="btn btn-default" data-dismiss="alert">稍后处理</button>
</p>
</div>
</div>