验证状态
Bootstrap 包含了错误、警告和成功消息的验证样式。只需要对父元素简单地添加适当的 class（.has-warning、 .has-error 或 .has-success）即可使用验证状态。
实例：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Bootstrap历练实例：验证状态</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width,initial-scale=1.0" />
<link rel="stylesheet" href="bootstrap-3.3.5-dist/css/bootstrap.min.css" />
</head>
<body>
<div class="container">
<form class="form-horizontal" role="form">
<div class="form-group has-success">
<label for="success" class="control-label col-sm-2">输入成功：</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="success" />
</div>
</div>
<br />
<div class="form-group has-warning">
<label for="warning" class="control-label col-sm-2">输入警告：</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="warning" />
</div>
</div>
<br />
<div class="form-group has-danger">
<label for="danger" class="control-label col-sm-2">输入危险：</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="danger" />
</div>
</div>
<br />
<div class="form-group has-error">
<label for="error" class="control-label col-sm-2">输入危险：</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="error" />
</div>
</div>
</form>
</div>
<script src="jQuery/jquery-2.1.4.js"></script>
<script src="bootstrap-3.3.5-dist/js/bootstrap.min.js"></script>
</body>
</html>