<form action="">

<div class="form-group">

    <div class="input-group">

        <input

        type="text"

        class="form-control"

        placeholder="请输入用户名" />

        <div class="input-group-append">

            <div class="input-group-text">

                <i class="fa fa-user" aria-hidden="true"></i>

            </div>

        </div>

    </div>

</div>

<div class="formgroup">

    <div class="input-group">

        <input

        type="password"

        class="form-control"

        placeholder="请输入密码" />

        <div class="input-group-append">

            <div class="input-group-text">

                <i class="fa fa-lock" aria-hidden="true"></i>

            </div>

        </div>

    </div>

</div>

</form>