bootstrap3 input 输入框图标背景

<div style="padding: 100px 100px 10px;">
<form class="bs-example bs-example-form" role="form">
<div class="input-group input-group-lg">
<span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>
<input type="text" class="form-control">
</div><br>
<div class="input-group">
<span class="input-group-addon">@</span>
<input type="text" class="form-control">
</div><br>
<div class="input-group input-group-sm">
<span class="input-group-addon">@</span>
<input type="text" class="form-control">
</div>
</form>
</div>

//在<pre name="code" class="html"><span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>

这里面你可以加你想要的，换图标的话去官网找吧，后面的<i></i>就是控制图标的。