C#_.NetCore_Web項目_EXCEL數據導出

項目需要引用NPOI的Nuget包：DotNetCore.NPOI-v1.2.2 A-前端觸發下載Excel的方法有三種： 1-JS-Url跳轉請求-後臺需要返迴文件流數據： 2-使用form+iframe請求文件流-後臺需要返迴文件流數據： 3-JS-Fetch請求使用Blob保存二進位文件流數據 ...

項目需要引用NPOI的Nuget包：DotNetCore.NPOI-v1.2.2

A-前端觸發下載Excel的方法有三種：

　　1-JS-Url跳轉請求-後臺需要返迴文件流數據：

window.Location.href = "/ajax/toolhelper.js?action=reBuyExport&beginTime=" + beginTime + "&endTime=" + endTime;

　　2-使用form+iframe請求文件流-後臺需要返迴文件流數據：

<form target="downLoadIframe" method="post" action="/ajax/toolhelper.js?action=reBuyExport">
        <div class="form-group">
            <label for="datetime">beginTime:</label>
            <input type="date" class="form-control" name="beginTime" placeholder="Enter beginTime" />
        </div>
        <div class="form-group">
            <label for="datetime">endTime:</label>
            <input type="date" class="form-control" name="endTime" placeholder="Enter endTime">
        </div>
        <button type="submit" class="btn btn-primary" id="btnExport">導出Excel</button>
    </form>
    <iframe id="downLoadIframe" name="downLoadIframe" style="display:none;"></iframe>

　　3-JS-Fetch請求使用Blob保存二進位文件流數據，通過A標簽下載流文件-後臺需要返迴文件流數據：

　　領導推薦這種方法，經過檢驗的，可以應對大文件下載的超時問題

fetch(url).then(function (res) {
                    res.blob().then(function (blob) {
                        var a = document.createElement('a');
                        var url = window.URL.createObjectURL(blob);
                        a.href = url;
                        a.download = fileName;
                        a.click();
                        window.URL.revokeObjectURL(url);
                    });
                });

B-後臺返迴流數據：

Core下的Excel幫助類

/// <summary>
    /// EXCEL幫助類
    /// </summary>
    /// <typeparam name="T">泛型類</typeparam>
    /// <typeparam name="TCollection">泛型類集合</typeparam>
    public class ExcelHelp<T, TCollection> where TCollection : List<T> where T : new()
    {
        public static ExcelHelp<T, TCollection> INSTANCE = new ExcelHelp<T, TCollection>();
        //獲取httpResponse對象原位置，放在這裡不知道會報錯：伺服器無法在發送 HTTP 標頭之後追加標頭
        //可能是這裡拿到的httpResponse對象不是最新請求的對象導致的，將其放到方法內部即可
        //HttpResponse baseResponse = HttpContext.Current.Response;

        /// <summary>
        /// 將數據導出EXCEL
        /// </summary>
        /// <param name="tList">要導出的數據集</param>
        /// <param name="fieldNameAndShowNameDic">鍵值對集合（鍵：欄位名，值：顯示名稱）</param>
        /// <param name="httpResponse">響應</param>
        /// <param name="excelName">文件名（必須是英文或數字）</param>
        /// <returns></returns>
        public async Task ExportExcelData(TCollection tList, Dictionary<string, string> fieldNameAndShowNameDic, HttpResponse httpResponse, string excelName = "exportResult")
        {
            IWorkbook workbook = new HSSFWorkbook();
            ISheet worksheet = workbook.CreateSheet("sheet1");

            List<string> columnNameList = fieldNameAndShowNameDic.Values.ToList();
            //設置首列顯示
            IRow row1 = worksheet.CreateRow(0);
            ICell cell = null;
            ICellStyle cellHeadStyle = workbook.CreateCellStyle();
            //設置首行字體加粗
            IFont font = workbook.CreateFont();
            font.Boldweight = short.MaxValue;
            cellHeadStyle.SetFont(font);
            for (var i = 0; i < columnNameList.Count; i++)
            {
                cell = row1.CreateCell(i);
                cell.SetCellValue(columnNameList[i]);
                cell.CellStyle = cellHeadStyle;
            }

            //根據反射創建其他行數據
            var raws = tList.Count;
            Dictionary<int, PropertyInfo> indexPropertyDic = this.GetIndexPropertyDic(fieldNameAndShowNameDic.Keys.ToList());

            for (int i = 0; i < raws; i++)
            {
                row1 = worksheet.CreateRow(i + 1);

                for (int j = 0; j < fieldNameAndShowNameDic.Count; j++)
                {
                    cell = row1.CreateCell(j);
                    if (indexPropertyDic[j].PropertyType == typeof(int)
                        || indexPropertyDic[j].PropertyType == typeof(decimal)
                        || indexPropertyDic[j].PropertyType == typeof(double))
                    {
                        cell.SetCellValue(Convert.ToDouble(indexPropertyDic[j].GetValue(tList[i])));
                    }
                    else if (indexPropertyDic[j].PropertyType == typeof(DateTime))
                    {
                        cell.SetCellValue(Convert.ToDateTime(indexPropertyDic[j].GetValue(tList[i]).ToString()));
                    }
                    else if (indexPropertyDic[j].PropertyType == typeof(bool))
                    {
                        cell.SetCellValue(Convert.ToBoolean(indexPropertyDic[j].GetValue(tList[i]).ToString()));
                    }
                    else
                    {
                        cell.SetCellValue(indexPropertyDic[j].GetValue(tList[i]).ToString());
                    }
                }
                //設置行寬度自適應
                worksheet.AutoSizeColumn(i, true);
            }

            MediaTypeHeaderValue mediaType = new MediaTypeHeaderValue("application/vnd.ms-excel");
            mediaType.Encoding = System.Text.Encoding.UTF8;

            httpResponse.ContentType = mediaType.ToString();
            //設置導出文件名
            httpResponse.Headers.Add("content-disposition", $"attachment;filename={excelName}.xls");
            MemoryStream ms = new MemoryStream();
            workbook.Write(ms);
            //這句代碼非常重要，如果不加，會報：打開的EXCEL格式與擴展名指定的格式不一致
            ms.Seek(0, SeekOrigin.Begin);
            byte[] myByteArray = ms.GetBuffer();
            httpResponse.Headers.Add("Content-Length", myByteArray.Length.ToString());
            await httpResponse.Body.WriteAsync(myByteArray, 0, myByteArray.Length);
        }

        /// <summary>
        /// 根據屬性名順序獲取對應的屬性對象
        /// </summary>
        /// <param name="fieldNameList"></param>
        /// <returns></returns>
        private Dictionary<int, PropertyInfo> GetIndexPropertyDic(List<string> fieldNameList)
        {
            Dictionary<int, PropertyInfo> indexPropertyDic = new Dictionary<int, PropertyInfo>(fieldNameList.Count);
            List<PropertyInfo> tPropertyInfoList = typeof(T).GetProperties().ToList();
            PropertyInfo propertyInfo = null;
            for (int i = 0; i < fieldNameList.Count; i++)
            {
                propertyInfo = tPropertyInfoList.Find(m => m.Name.Equals(fieldNameList[i], StringComparison.OrdinalIgnoreCase));
                indexPropertyDic.Add(i, propertyInfo);
            }

            return indexPropertyDic;
        }

    }

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Core的中間件請求方法：

TBDataHelper為提前註入的資料庫幫助類，需要改成自己的數據請求類；

自定義的導出文件名，不能輸入中文，暫時還沒有找到解決辦法；

BaseMiddleware為基類，切記基類中只能存常態化的數據，如：下一中間件，配置，緩存。不能存放Request，Response等！！！

public class ToolHelperMiddleware : BaseMiddleware
    {
        public TBDataHelper TBDataHelper { get; set; }
        public ToolHelperMiddleware(RequestDelegate next, ConfigurationManager configurationManager, IMemoryCache memoryCache, TBDataHelper tBDataHelper) : base(next, configurationManager, memoryCache)
        {
            this.TBDataHelper = tBDataHelper;
        }

        public async Task Invoke(HttpContext httpContext)
        {
            var query = httpContext.Request.Query;
            var queryAction = query["action"];

            switch (queryAction)
            {
                case "reBuyExport":
                    await this.ReBuyExport(httpContext);
                    break;
            }
        }

        /// <summary>
        /// 復購數據導出
        /// </summary>
        /// <param name="httpContext"></param>
        /// <returns></returns>
        private async Task ReBuyExport(HttpContext httpContext)
        {
            var request = httpContext.Request;
            var response = httpContext.Response;
            var requestForm = request.Form;

            try
            {
                DateTime beginTime = Convert.ToDateTime(requestForm["beginTime"]);
                DateTime endTime = Convert.ToDateTime(requestForm["endTime"]);

                List<RebuyModel> rebuyModelList = this.TBDataHelper.SelectReBuyList(beginTime, endTime);

                Dictionary<string, string> fieldNameAndShowNameDic = new Dictionary<string, string>(0);
                fieldNameAndShowNameDic.Add("UserID", "用戶ID");
                fieldNameAndShowNameDic.Add("PayCount", "支付數");
                fieldNameAndShowNameDic.Add("BeforeBuyCount", beginTime.ToString("MM/dd") + "之前支付數");

                string fileName = $"{beginTime.ToString("MMdd")}_{endTime.ToString("MMdd")}ReBuyExport_{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")}";
                await ExcelHelp<RebuyModel, List<RebuyModel>>.INSTANCE.ExportExcelData(rebuyModelList, fieldNameAndShowNameDic, response, fileName);
            }
            catch (Exception e)
            {
                throw e;
            }
        }

    }

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/// <summary>
    /// 中間件基類
    /// </summary>
    public abstract class BaseMiddleware
    {
        /// <summary>
        /// 等同於ASP.NET裡面的WebCache(HttpRuntime.Cache)
        /// </summary>
        protected IMemoryCache MemoryCache { get; set; }

        /// <summary>
        /// 獲取配置文件裡面的配置內容
        /// </summary>
        protected ConfigurationManager ConfigurationManager { get; set; }

        /// <summary>
        /// 下一個中間件
        /// </summary>
        protected RequestDelegate Next { get; set; }

        public BaseMiddleware(RequestDelegate next, params object[] @params)
        {
            this.Next = next;
            foreach (var item in @params)
            {
                if (item is IMemoryCache)
                {
                    this.MemoryCache = (IMemoryCache)item;
                }
                else if (item is ConfigurationManager)
                {
                    this.ConfigurationManager = (ConfigurationManager)item;
                }
            }
        }

    }

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