layui框架实战案例(2)：layui文件上传PHP后台参数获取方式及JSON返回格式

<div class=" layui-fluid layui-bg-white">
    <fieldset class="layui-elem-field layui-field-title" style="margin-top: 30px;">
        <legend>拖拽上传</legend>
    </fieldset>
    <div class="layui-upload-drag" id="demoimport">
        <i class="layui-icon"></i>
        <p>点击上传，或将文件拖拽到此处</p>
    </div>
    <fieldset class="layui-elem-field layui-field-title" style="margin-top: 30px;">
        <legend>为节省服务器开销，导入文件均为临时文件。</legend>
    </fieldset>
</div>

   layui.use('upload', function () {
        var $ = layui.jquery
                , upload = layui.upload;
        //拖拽上传
        upload.render({
            elem: '#demoimport'
            , url: '?m=Demo&a=uploadFile'
            , accept: 'file' //普通文件
            , exts: 'xls|xlsx' //只允许上传压缩文件
            , done: function (res) {
                //如果上传失败
                if (res.code == 0) {
                    return layer.msg('上传失败,' + res.err);
                }
                //上传成功
                if (res.code > 0) {
                    layer.alert(res.err, {icon: 6}, function () {
                        var index = parent.layer.getFrameIndex(window.name);
                        parent.layer.close(index);
                        window.parent.location.reload();
                    });
                }
            }
        });
    });

//获取表格的大小，限制上传表格的大小5M
  $file_size = $_FILES['file']['size'];
  if ($file_size > 5 * 1024 * 1024) {
    $res['code'] = '0';
    $res['err']  = '只能上传小于5M大小的文件!';
    die(json_encode($res));
  }
//限制上传表格类型
  $file_type = $_FILES['file']['type'];
  if ($file_type != 'application/vnd.ms-excel') {
    $res['code'] = '0';
    $res['err']  = '上传失败，只能上传excel2003的xls格式!';
    die(json_encode($res));
  }