The following code adds the disabled attribute to <button> buttons.
<!DOCTYPE HTML>
<html>
<head>
<link href="http://java2s.com/style/bootstrap.min.css" rel="stylesheet">
</head><!-- ww w. ja v a 2s . com-->
<body style='margin:20px;'>
<button type="button" class="btn btn-lg btn-primary" disabled="disabled">Primary button</button>
<button type="button" class="btn btn-default btn-lg" disabled="disabled">Button</button>
</body>
</html>