C# Excel导入以流的方式保存，不保存到本地

在System.IO名称空间中有以下类 

BinaryReader/Writer 

TextReader/Writer 

Stream 

其中类Stream为抽象类。由此有三个派生类： 

MemoryStream：对内存进行读取与写入 

BufferedStream：对缓冲器进行读取/写入 

FileStream：对文件执行读取与写入 

TextReader/Writer为抽象类。由此派生类： 

StreamReader/StreamWirter 

StringReader/StreamWriter 

需要引入命名空间: 

using System.IO

protected void btnExcel_Click(object sender, EventArgs e)
    {
        //exel导入以流的方式存储
        HttpFileCollection files = HttpContext.Current.Request.Files;
        if (files == null || files.Count == 0)
        {
            throw new Exception("您没有选择导入文件！");
        }
        bool useOldVersionOfExcel = false;
        string aLastName = files[0].FileName.Substring(files[0].FileName.LastIndexOf(".") + 1, (files[0].FileName.Length - files[0].FileName.LastIndexOf(".") - 1)); //扩展名
        if (aLastName == "xlsx")
        {
            useOldVersionOfExcel = false;
        }else
        {
            useOldVersionOfExcel = true;
        }
        DataSet ds = ExcelSteamToDataSet(fulV12.FileContent, useOldVersionOfExcel);

        #region MyRegion
        //string fullName = HttpContext.Current.Server.MapPath("~") + @"导入Excel" + System.IO.Path.GetExtension(files[0].FileName).ToLower();
        //files[0].SaveAs(fullName);
        //DataSet ds = ExcelToDataSet(fullName);
        //if (File.Exists(fullName))
        //    File.Delete(fullName);


        DataTable dt = new DataTable();
        DataColumn col1 = new DataColumn("sid");
        dt.Columns.Add(col1);
        DataColumn dc1 = new DataColumn("V1", Type.GetType("System.String"));
        DataColumn dc2 = new DataColumn("V2", Type.GetType("System.String"));
        DataColumn dc3 = new DataColumn("V3", Type.GetType("System.String"));
        DataColumn dc7 = new DataColumn("V7", Type.GetType("System.String"));
        DataColumn dc4 = new DataColumn("V4", Type.GetType("System.String"));
        DataColumn dc5 = new DataColumn("V5", Type.GetType("System.String"));
        DataColumn dc9 = new DataColumn("V9", Type.GetType("System.String"));
        DataColumn dc10 = new DataColumn("V10", Type.GetType("System.String"));
        dt.Columns.Add(dc1);
        dt.Columns.Add(dc2);
        dt.Columns.Add(dc3);
        dt.Columns.Add(dc7);
        dt.Columns.Add(dc4);
        dt.Columns.Add(dc5);
        dt.Columns.Add(dc9);
        dt.Columns.Add(dc10);
        if (ds.Tables[0].Rows.Count > 0)
        {
            for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
            {
                DataRow dr = dt.NewRow();
                dr["V1"] = ds.Tables[0].Rows[i][0].ToString();
                dr["V2"] = ds.Tables[0].Rows[i][1].ToString();
                dr["V3"] = ds.Tables[0].Rows[i][2].ToString();
                dr["V7"] = ds.Tables[0].Rows[i][3].ToString();
                dr["V4"] = ds.Tables[0].Rows[i][4].ToString();
                dr["V5"] = ds.Tables[0].Rows[i][5].ToString();
                dr["V9"] = ds.Tables[0].Rows[i][6].ToString();
                dr["V10"] = ds.Tables[0].Rows[i][7].ToString();
                dt.Rows.Add(dr);
            }

        }
        BindGridView(dt);

        #endregion




    }

// <summary> 流的方式接收，进行读取内容
    /// 
    /// </summary>
    /// <param name="fs"></param>
    /// <returns></returns>
    public static DataSet ExcelSteamToDataSet(Stream fs,bool useOldVersionOfExcel)
    {
        DataSet res = new DataSet();
        IWorkbook workbook;// = new XSSFWorkbook(fs);
        if (useOldVersionOfExcel)
        {
            //旧版
            workbook = new HSSFWorkbook(fs);
        }
        else
        {   //2017以上版本
            workbook = new XSSFWorkbook(fs);
        }
       
        int sheetNum = workbook.NumberOfSheets;
        for (int index = 0; index < sheetNum; index++)
        {
            ISheet sheet = workbook.GetSheetAt(index);
            DataTable dt = new DataTable(sheet.SheetName);
            if (sheet.LastRowNum == 0)
            {
                continue;
            }
            //表头  
            IRow header = sheet.GetRow(sheet.FirstRowNum);
            List<int> columns = new List<int>();
            for (int i = 0; i < header.LastCellNum; i++)
            {
                object obj = header.GetCell(i);
                if (obj == null || obj.ToString() == string.Empty)
                {
                    dt.Columns.Add(new DataColumn("Columns" + i.ToString()));
                }
                else
                    dt.Columns.Add(new DataColumn(obj.ToString()));
            }
            //数据  
            for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
            {
                DataRow dr = dt.NewRow();
                bool hasValue = false;
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    try
                    {
                        if (sheet.GetRow(i) == null)
                        {
                            hasValue = false;
                            break;
                        }

                        //判断当前单元格的内容是否为日期格式的数据，是则进行处理
                        ICell cell = sheet.GetRow(i).GetCell(j);
                        if (cell.CellType == CellType.Numeric && DateUtil.IsCellDateFormatted(cell))
                        {
                            dr[j] = cell.DateCellValue.ToString();
                        }
                        else
                        {
                            dr[j] = cell.ToString();
                        }
                        //dr[j] = sheet.GetRow(i).GetCell(j);
                        if (dr[j] != null && dr[j].ToString() != string.Empty)
                        {
                            hasValue = true;
                        }
                    }
                    catch { }
                }
                if (hasValue)
                {
                    dt.Rows.Add(dr);
                }
            }
            res.Tables.Add(dt);
        }
        return res;
    }

 版本很旧啦，突然跟我说文件不能保存在本地，只能以流的方式保存，