bootstrap--导航条下的搜索框中引入小图标

<form action="" class="navbar-form">
  <div class="form-group has-feedback">
    <label for="pw"></label>
    <span class="glyphicon glyphicon-search form-control-feedback"></span>
    <input type="text" id="pw" class="form-control" placeholder="search">
  </div>
</form>

　　主要css解释

.has-feedback {
  position: relative;
}
  .navbar-form .has-feedback .form-control-feedback {
    top: 0;
  }
.form-control-feedback {
  position: absolute;
  top: 0;
  right: 0;
  z-index: 2;
  display: block;
  width: 34px;
  height: 34px;
  line-height: 34px;
  text-align: center;
  pointer-events: none;
}