{#         multiple多选           #}
<div class="btn btn-primary btn-xs upload" style="position: relative">
    <div><i class="fa fa-upload" aria-hidden="true"></i> 上传文件</div>
    <input type="file" multiple name="uploadFile" id="uploadFile">
</div>

css样式
        .panel-default > .panel-heading .function .upload {
            overflow: hidden;
        }

        .panel-default > .panel-heading .function .upload input {
            opacity: 0;
            position: absolute;
            top: 0;
            bottom: 0;
            width: 76px;
            left: -2px;
            overflow: hidden;
        }