【C#】NPOI execl下载

 public class ExcelHelper
    {
        public static string Version
        {
            get { return "0.1"; }
        }

        readonly static int EXCEL03_MaxRow = 65535;
        public static DataTable ToDataTable<T>(IEnumerable<T> collection, string lang = null)
        {
            var props = typeof(T).GetProperties();
            var dt = new DataTable();
            if (lang != null && lang.ToLower() == "zh-cn")
            {
                PropertyInfo[] peroperties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
                foreach (PropertyInfo property in peroperties)
                {
                    object[] objs = property.GetCustomAttributes(typeof(DescriptionAttribute), true);
                    if (objs.Length > 0)
                    {
                        dt.Columns.Add(((DescriptionAttribute)objs[0]).Description);
                    }
                    else
                    {
                        dt.Columns.Add(new DataColumn(property.Name, property.PropertyType));
                    }
                }
            }
            else
            {
                dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name, p.PropertyType)).ToArray());
            }

            if (collection.Count() > 0)
            {
                for (int i = 0; i < collection.Count(); i++)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in props)
                    {
                        object obj = pi.GetValue(collection.ElementAt(i), null);
                        tempList.Add(obj);
                    }
                    object[] array = tempList.ToArray();
                    dt.LoadDataRow(array, true);
                }
            }
            return dt;
        }

        public static FileStream SaveFile<T>(string path,IEnumerable<T> collection,string tableName,string lang)
        {
            try
            {
                IWorkbook book = new HSSFWorkbook();
                var table = ToDataTable<T>(collection, lang);
                table.TableName = tableName;
                FillWorkBookData(book, table);
                FileStream file = new FileStream(path, FileMode.Create);
                book.Write(file);
                file.Close();
                file.Dispose();

                return new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
            }
            catch (Exception ex)
            {
                return null;
            }
        }

        public static FileStream SaveFile(string path, DataSet set)
        {
            try
            {
                IWorkbook book = new HSSFWorkbook();

                for(int i = 0; i < set.Tables.Count;i++)
                {
                    FillWorkBookData(book, set.Tables[i]);
                }

                FileStream file = new FileStream(path, FileMode.Create);
                book.Write(file);
                file.Close();
                file.Dispose();

                return new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
            }
            catch (Exception ex)
            {
                return null;
            }
        }

        public static IWorkbook FillWorkBookDataForPage(IWorkbook book,DataTable dt)
        {
            book = book ?? new HSSFWorkbook();
            if (dt.Rows.Count < EXCEL03_MaxRow)
                FillWorkBookData(book,dt, 0, dt.Rows.Count - 1);
            else
            {
                int page = dt.Rows.Count / EXCEL03_MaxRow;
                for (int i = 0; i < page; i++)
                {
                    int start = i * EXCEL03_MaxRow;
                    int end = (i * EXCEL03_MaxRow) + EXCEL03_MaxRow - 1;
                    dt.TableName = $"{dt.TableName}-i";
                    FillWorkBookData(book, dt, start, end); 
                }
                int lastPageItemCount = dt.Rows.Count % EXCEL03_MaxRow;
                dt.TableName = $"{dt.TableName}-{page}";
                FillWorkBookData(book,dt, dt.Rows.Count - lastPageItemCount, lastPageItemCount);
            }
            return book;
        }

        public static IWorkbook FillWorkBookData(IWorkbook book, DataTable dt, ICellStyle style, int startRow = 0, int endRow = -1)
        {
            book = book ?? new HSSFWorkbook();

            ISheet sheet = book.CreateSheet(dt.TableName);

            ICellStyle cellStyle = book.CreateCellStyle();
            IFont font = book.CreateFont();
            font.FontHeightInPoints = 12;
            font.Boldweight = (short)FontBoldWeight.Bold;
            cellStyle.BorderTop = cellStyle.BorderRight = cellStyle.BorderBottom = cellStyle.BorderLeft = BorderStyle.Thin;
            cellStyle.SetFont(font);

            IRow header = sheet.CreateRow(0);
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                ICell cell = header.CreateCell(i);
                string val = dt.Columns[i].Caption ?? dt.Columns[i].ColumnName;
                cell.SetCellValue(val);
                cell.CellStyle = cellStyle;
            }
            int rowIndex = 1;
            if (endRow < 0) endRow = dt.Rows.Count-1;

            for (int i = startRow; i <= endRow; i++)
            {
                DataRow dtRow = dt.Rows[i];
                IRow excelRow = sheet.CreateRow(rowIndex++);
                for (int j = 0; j < dtRow.ItemArray.Length; j++)
                {
                    var col = excelRow.CreateCell(j);
                    col.SetCellValue(dtRow[j].ToString());
                    if (style != null)
                    {
                        col.CellStyle = style;
                    }
                }
            }

            return book;
        }

        /// <summary>
        /// 添加数据表格默认样式
        /// </summary>
        /// <param name="book"></param>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static IWorkbook FillWorkBookData(IWorkbook book,DataTable dt, int startRow = 0, int endRow = -1)
        {
            book = book ?? new HSSFWorkbook();

            ICellStyle cellStyle = book.CreateCellStyle();
            cellStyle.BorderTop = cellStyle.BorderRight = cellStyle.BorderBottom = cellStyle.BorderLeft = BorderStyle.Thin;

            return FillWorkBookData(book, dt, cellStyle, startRow, endRow);
        }

    }

[HttpPost, Route("api/Template/GetColumnFile")]
        public HttpResponseMessage GetColumnFile([FromBody]GetColumnRequest req)
        {
            HttpResponseMessage result;

            try
            {
                var columns = service.GetColumn(req.Object, req.TableName) ?? new List<VColumn>();
                var tables = service.GetTable(req.Object) ?? new List<VTable>();
                DataSet set = new DataSet();
                var coltable = ExcelHelper.ToDataTable(columns, "zh-cn");
                coltable.TableName = $"{req.TableName}表信息";
                set.Tables.Add(coltable);
                var tabTable = ExcelHelper.ToDataTable(tables);
                tabTable.TableName = $"{req.Object.Database}数据库信息";
                set.Tables.Add(tabTable);


                string basePath = System.Web.Hosting.HostingEnvironment.MapPath(@"~/") + "TransitionFile\\";
                string fileName = Guid.NewGuid().ToString();
                string path = $"{basePath}{fileName}.xls";

                DirectoryHelper.CreateIfNotExists(basePath);

                var stream = ExcelHelper.SaveFile(path, set);

                result = new HttpResponseMessage(System.Net.HttpStatusCode.OK) { Content = new StreamContent(stream) };
                
                result.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
                result.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment")
                {
                    FileName = HttpUtility.UrlEncode("123.xls")
                };

                return result;
            }
            catch (Exception ex)
            {
                return new HttpResponseMessage(HttpStatusCode.NotFound);
            }
        }

testClick(){
      var request = {
          tableName: this.columnNodeData.label,
          object: this.columnNodeData.conn
        };
      this.$http
        .post("/api/Template/GetColumnFile",pamas,{ ‘responseType‘: ‘blob‘}) //请求方式 post get put delete等等
        .then(res => {
          var blob = new Blob([res.data], {type: ‘application/vnd.openxmlformats-officedocument.wordprocessingml.document;charset=utf-8‘}); //application/vnd.openxmlformats-officedocument.wordprocessingml.document这里表示doc类型
          var contentDisposition = res.headers[‘content-disposition‘];  //从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 设置的文件名;
          var patt = new RegExp("filename=([^;]+\\.[^\\.;]+);*");
          var result = patt.exec(contentDisposition);
          var filename = result[1];
          var downloadElement = document.createElement(‘a‘);
          var href = window.URL.createObjectURL(blob); //创建下载的链接
          downloadElement.style.display = ‘none‘;
          downloadElement.href = href;
          downloadElement.download =filename ; //下载后文件名
          document.body.appendChild(downloadElement);
          downloadElement.click(); //点击下载
          document.body.removeChild(downloadElement); //下载完成移除元素
          window.URL.revokeObjectURL(href); //释放掉blob对象
        })
        .catch(err => {
          this.$message.error(err);
        });
    }

     //var workbook = ExcelToHtmlUtils.LoadXls(path);

                //ExcelToHtmlConverter excelToHtmlConverter = new ExcelToHtmlConverter();

                ////set output parameter
                //excelToHtmlConverter.OutputColumnHeaders = false;
                //excelToHtmlConverter.OutputHiddenColumns = true;
                //excelToHtmlConverter.OutputHiddenRows = true;
                //excelToHtmlConverter.OutputLeadingSpacesAsNonBreaking = false;
                //excelToHtmlConverter.OutputRowNumbers = true;
                //excelToHtmlConverter.UseDivsToSpan = true;

                ////process the excel file
                //excelToHtmlConverter.ProcessWorkbook(workbook);

                ////output the html file
                //excelToHtmlConverter.Document.Save(Path.ChangeExtension(path, "html"));