LayUI多文件上传，支持历史上传预览

   <div class="layui-upload">
                    <button type="button" class="layui-btn layui-btn-normal" id="ID-upload-demo-files">选择多文件</button>

                    <div class="layui-upload-list">
                        <table class="layui-table">
                            <colgroup>
                                <col style="min-width: 100px;">
                                <col width="100">
                                <col width="150">
                                <col width="260">
                                <col width="100">
                            </colgroup>
                            <thead>
                            <th>图片</th>
                            <th>文件名</th>
                            <th>大小</th>
                            <th>上传进度</th>
                            <th>操作</th>
                            </thead>
                            @*历史数据*@
                            <tbody id="ID-upload-pre-files-list">
                                @{
                                    var filelist = ViewData["UploadedList"] as List<MultiPics>;
                                    if (filelist != null && filelist.Count > 0)
                                    {
                                        foreach (var file in filelist)
                                        {
                                            <tr id="fileList@((filelist.IndexOf(file)+1).ToString())">
                                                <td>
                                                    <img src="@file.Content" class="tdPreImg">
                                                </td>
                                                <td>
                                                    <i class="del-img" id="@((filelist.IndexOf(file)+1).ToString())" data-src="@file.FilePath"></i>@file.FileName
                                                </td>
                                                <td>@file.FileSize KB</td>
                                                <td>已上传</td>
                                                <td>
                                                    @*因为layui按钮会提交，此处后台加载的图片，不用layui按钮*@
                                                    <input type="button" value="删除" class="btn_del" id="btn_del@((filelist.IndexOf(file)+1).ToString())" data-index="@((filelist.IndexOf(file)+1).ToString())" />
                                                </td>
                                            </tr>
                                        }
                                    }
                                }
                            </tbody>
                            @*当前上传*@
                            <tbody id="ID-upload-demo-files-list">
                            </tbody>
                        </table>
                    </div>

                    <button type="button" class="layui-btn" id="ID-upload-demo-files-action">开始上传</button>
                </div>

 layui.use(function () {
            var upload = layui.upload;
            var element = layui.element;
            var $ = layui.$;
            var deliveryId = $("#LogID").val();

            // 制作多文件上传表格
            var uploadListIns = upload.render({
                elem: '#ID-upload-demo-files',
                elemList: $('#ID-upload-demo-files-list'), // 列表元素对象
                url: '/Ship/OrderInfo/UploadImages?id=' + deliveryId,
                accept: 'images',
                multiple: true,
                number: 10,
                exts: "png|jpg|jpeg",
                auto: false,
                bindAction: '#ID-upload-demo-files-action',
                choose: function (obj) {
                    var that = this;
                    // 将每次选择的文件追加到文件队列
                    var files = this.files = obj.pushFile();
                    // 读取本地文件
                    obj.preview(function (index, file, result) {
                        //console.log('choose' + index)
                        var tr = $(['<tr id="upload-' + index + '">',
                            '<td>'
                                + '<img src=\'' + result + '\' class=\'tdPreImg\'>'
                            + '</td>',

                            '<td>'
                            + '<i class="del-img" id="del-'+index+'" data-src=""></i>'
                            + file.name + '</td>',
                            '<td>' + (file.size / 1024).toFixed(1) + 'kb</td>',
                            '<td><div class="layui-progress" lay-filter="progress-demo-' + index + '">'
                            + '<div class="layui-progress-bar" lay-percent=""></div></div>'
                            + '</td>',

                            '<td>',

                            '<button class="layui-btn layui-btn-xs demo-reload layui-hide">重传</button>',
                            '<button class="layui-btn layui-btn-xs layui-btn-danger demo-delete">删除</button>',
                            '</td>',

                            '</tr>'].join(''));

                        // 单个重传
                        tr.find('.demo-reload').on('click', function () {
                            obj.upload(index, file);
                        });

                        // 删除
                        tr.find('.demo-delete').on('click', function () {
                            delete files[index]; // 删除对应的文件
                            tr.remove(); // 删除表格行
                            // 清空 input file 值，以免删除后出现同名文件不可选
                            uploadListIns.config.elem.next()[0].value = '';
                        });

                        that.elemList.append(tr);
                        element.render('progress'); // 渲染新加的进度条组件
                    });
                },
                done: function (res, index, upload) { // 成功的回调
                    //console.log('done' + index)

                    // 删除文件队列已经上传成功的文件【很重要防止之前的图片重复上传】
                    delete this.files[index];
                    var that = this;

                    var tr = that.elemList.find('tr#upload-' + index);
                    var tds = tr.children();
                    if (res.result) { //上传成功
                        $('#del-' + index).attr('data-src', res.data)

                        //清空操作
                        tds.eq(3).html('');
                        tds.eq(3).html('上传成功！');
                    }
                    else {
                        this.error(index, upload);
                        tds.eq(3).html('上传失败！');
                        //弹框显示错误信息
                        layer.msg("上传失败！" + res.msg);
                        //调试人员查看，暂时保留
                        console.log("上传失败！" + res.msg + "#" + res.data);
                    }
                },
                allDone: function (obj) { // 多文件上传完毕后的状态回调
                    console.log(obj);
                },
                error: function (index, upload) { // 错误回调

                    var that = this.elemList.find('tr#upload-' + index);
                    //console.log(that);
                    that.find(".demo-reload").removeClass('layui-hide');
                },
                progress: function (n, elem, e, index) {
                    element.progress('progress-demo-' + index, n + '%'); // 执行进度条。n 即为返回的进度百分比
                }
            });
        });

    var main = {
            @*初始化，静态js*@
            Init: function () {
                $(document).ready(function () {
                    @* Layui自带图片删除，历史图片的删除需特殊处理 *@
                    $(".btn_del").click(function () {
                        var _index = this.getAttribute("data-index");
                        var _tr = $("#fileList" + _index);
                        $("#ID-upload-pre-files-list")[0].removeChild(_tr[0]);
                    })
                });
            },
            @* 获取参数，前台不提交文件，后台绑定 *@
            SaveSignBack: function () {
                @*图片地址列表*@
                var _BackImage = "";
                @*发货日志*@
                var _ID = $("#LogID").val();
var _Note= $("#Note").val();

                //图片提取并限制数量
                var images_ids = $('.del-img');
                @*限制上传图片数量*@
                if (images_ids.length > 10) {
                    layer.msg("图片最多选择10张");
                    return false;
                }

                @*以|竖线分割，拼接字符串*@
                if (images_ids.length) {
                    var images = '';
                    $.each(images_ids, function (index, val) {
                        if (images == '') {
                            images += $(val).attr('data-src')
                        } else {
                            images += '|' + $(val).attr('data-src')
                        }
                    });
                    //$(data.form).append('<input name="images" type="hidden" value="' + images + '">');//插入表单

                    //图片参数赋值
                    _BackImage= images;
                }

                @*获取表单内容序列化*@
                //var fileForm = $("#form1").serialize();

                //上传了图片，直接修改
                if (_BackImage.length) {
                    main.FormSubmit(_LogID, _Note, _BackImage);
                }
                //未上传图片，弹框提示
                else {
                    $.messager.confirm("提示", "您未上传图片，确定提交吗？", function (data) {
                        //确定
                        if (data) {
                            main.FormSubmit(_LogID, _Note, _BackImage);
                            return;
                        }
                        //修改，不处理
                        else { }
                    });
                }
             },
            @* 提交后台 *@
            FormSubmit: function (_LogID, _Note, _BackImage) {
                $.post("/ControllerName/OrderInfo/BackSubmit",
                        {
                            LogID: _LogID,
                            Note: _Note,
                            Images: _BackImage
                        },
                        function (obj) {
                            if (obj.result) {
                                layer.msg(obj.msg);
                                //parent.refresh();
                                parent.location.reload();
                                parent.CloseWin();
                            }
                            else {
                                $.messager.alert('Info', obj.msg, 'info');
                            }
                        }
                    );
            },
        }

        $(function () {
            main.Init();
        })

　　　　public ActionResult UploadImages(int ID = 0)
　　　　{
            ////防止异常加载图片覆盖，延时半秒 SaveAs
            //System.Threading.Thread.Sleep(500);

            try
            {
                #region 数据校验
                //登录状态校验
                if (CurrentUser.Id == 0)
                {
                    return Json(new { result = false, msg = "登录失效！", data = "" });
                }

                //获取回签单图片列表
                HttpFileCollectionBase files = HttpContext.Request.Files;
                //图片非空校验
                if (files.Count == 0)
                {
                    return Json(new { result = false, msg = "上传失败！请上传回签单图片！", data = "" });
                }

                //单个图片轮询上传，只能单张上传
                if (files.Count > 1)
                {
                    return Json(new { result = false, msg = "参数错误！", data = "" });
                }
                #endregion

                //上传文件计数
                var successCount = 0;
                //图片相对路径（用于数据库保存）
                string FilePath = string.Empty;
                //循环保存图片，实际单个图片上传
                for (int i = 0; i < files.Count; i++)
                {
                    #region 拼接文件名（不含路径）
                    //文件类型
                    var fileType = string.Empty;
                    //获取文件类型
                    if (files[i].ContentType == "image/jpeg" || files[i].ContentType == "image/jpg")
                    {
                        fileType = ".jpg";
                    }
                    else if (files[i].ContentType == "image/png")
                    {
                        fileType = ".png";
                    }

                    // 生成随机4位数字
                    var rand = (new Random()).Next(1000, 10000).ToString();
                    //文件名
                    var _name = ID + "_" + CurrentUser.Id + "_" + DateTime.Now.ToString("yyMMddHHmmsss") + "_" + rand;
                    //拼接文件名 回签图片名称格式：发货日志Id_上传人_年月日_4位随机数
                    var book = _name + fileType;
                    #endregion

                    //获取配置文件的回签单保存路径 SignBackUrl
                    string savePath = System.Configuration.ConfigurationManager.AppSettings["FileUrl"];
                    //按月分文件夹
                    FilePath = DateTime.Now.ToString("yyyyMM") + "/" + book;
                    //文件完整路径
                    string fileFullPath = savePath + "/" + FilePath;

                    //没有文件夹则创建
                    if (!Directory.Exists(savePath + "/" + DateTime.Now.ToString("yyyyMM")))
                    {
                        Directory.CreateDirectory(savePath + "/" + DateTime.Now.ToString("yyyyMM"));
                    }

                    #region 文件大小校验
                    //保存图片到服务器上
                    files[i].SaveAs(fileFullPath);

                    //创建文件 获取文件大小
                    var fileInfo = new FileInfo(fileFullPath);
                    //获取文件大小，单位KB  1KB=1024byte(字节)
                    decimal fileSize = (decimal)(fileInfo.Length > 0 ? (fileInfo.Length / 1024) : 0);
                    //2MB转成KB
                    var _2mb = (decimal)2 * 1024;
                    //获取大小异常
                    if (fileSize == 0)
                    {
                        //计算文件大小异常
                        return Json(new { result = false, msg = "计算文件大小异常 !", data = FilePath });
                    }
                    else if (fileSize != 0 && fileSize > _2mb)
                    {
                        //文件大小超出2MB
                        return Json(new { result = false, msg = "文件大小超出2MB，请修改后重试 !", data = FilePath });
                    }
                    #endregion//累计成功计数
                    successCount++;
                }

                if (successCount == files.Count)
                {
                    //成功返回，回调图片地址列表(相对地址)
                    return Json(new { result = true, msg = "上传成功 !", data = FilePath });
                }
                else
                {
                    //失败
                    return Json(new { result = false, msg = "上传失败 !", data = "[上传文件数: " + successCount + "]" });
                }
            }
            catch (Exception ex)
            {
                //抛出异常
                return Json(new { result = false, msg = "上传异常，请重试 !", data = "[Exception: " + ex.Message + "]" });
            }
        }