.NET 导入导出Excel

第一种方式：OleDb

需要安装office,且读数据慢,而且有数据格式的Cell读出数据不正确等问题.放弃。

第二种方式：NPOI开源库

使用NPOI导入导出Excel应该是.NET开发很常用的手段.

代码如下：

 public ExcelHelper(string fileName)
         {
             this.fileName = fileName;
             disposed = false;
         }

         /// <summary>
         /// 将DataTable数据导入到excel中
         /// </summary>
         /// <param name="data">要导入的数据</param>
         /// <param name="isColumnWritten">DataTable的列名是否要导入</param>
         /// <param name="sheetName">要导入的excel的sheet的名称</param>
         /// <returns>导入数据行数(包含列名那一行)</returns>
         public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten)
         {
             int i = ;
             int j = ;
             int count = ;
             ISheet sheet = null;

             fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
             if (fileName.IndexOf(".xlsx") > ) // 2007版本
                 workbook = new HSSFWorkbook();
             else if (fileName.IndexOf(".xls") > ) // 2003版本
                 workbook = new HSSFWorkbook();

             try
             {
                 if (workbook != null)
                 {
                     sheet = workbook.CreateSheet(sheetName);
                 }
                 else
                 {
                     return -;
                 }

                 if (isColumnWritten == true) //写入DataTable的列名
                 {
                     IRow row = sheet.CreateRow();
                     for (j = ; j < data.Columns.Count; ++j)
                     {
                         row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                     }
                     count = ;
                 }
                 else
                 {
                     count = ;
                 }

                 for (i = ; i < data.Rows.Count; ++i)
                 {
                     IRow row = sheet.CreateRow(count);
                     for (j = ; j < data.Columns.Count; ++j)
                     {
                         row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                     }
                     ++count;
                 }
                 workbook.Write(fs); //写入到excel
                 return count;
             }
             catch (Exception ex)
             {
                 Console.WriteLine("Exception: " + ex.Message);
                 return -;
             }
         }

         /// <summary>
         /// 将excel中的数据导入到DataTable中
         /// </summary>
         /// <param name="sheetName">excel工作薄sheet的名称</param>
         /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
         /// <returns>返回的DataTable</returns>
         public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn)
         {
             ISheet sheet = null;
             DataTable data = new DataTable();
             int startRow = ;
             try
             {
                 fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                 if (fileName.IndexOf(".xlsx") > ) // 2007版本
                     workbook = new XSSFWorkbook(fs);
                 else if (fileName.IndexOf(".xls") > ) // 2003版本
                     workbook = new HSSFWorkbook(fs);

                 if (sheetName != null)
                 {
                     sheet = workbook.GetSheetAt();
                     if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                     {
                         sheet = workbook.GetSheetAt();
                     }
                 }
                 else
                 {
                     sheet = workbook.GetSheetAt();
                 }
                 if (sheet != null)
                 {

                     IRow firstRow = sheet.GetRow();
                     int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数

                     if (isFirstRowColumn)
                     {
                         try
                         {
                             for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                             {
                                 ICell cell = firstRow.GetCell(i);
                                 if (cell != null)
                                 {
                                     string cellValue = cell.StringCellValue;
                                     if (cellValue != null)
                                     {
                                         DataColumn column = new DataColumn(cellValue);
                                         data.Columns.Add(column);
                                     }
                                 }
                             }
                             startRow = sheet.FirstRowNum + ;
                         }
                         catch (Exception e)
                         {

                         }

                     }
                     else
                     {
                         startRow = sheet.FirstRowNum;
                     }

                     //最后一列的标号
                     int rowCount = sheet.LastRowNum;
                     for (int i = startRow; i <= rowCount; ++i)
                     {
                         IRow row = sheet.GetRow(i);
                         if (row == null) continue; //没有数据的行默认是null　　　　　　　

                         DataRow dataRow = data.NewRow();
                         for (int j = row.FirstCellNum; j < cellCount; ++j)
                         {
                             ICell cell = row.GetCell(j);
                             if (cell != null)//同理，没有数据的单元格都默认是null
                             {
                                 if (cell.CellType == CellType.Numeric)
                                 {
                                     //NPOI中数字和日期都是NUMERIC类型的，这里对其进行判断是否是日期类型
                                     if (HSSFDateUtil.IsCellDateFormatted(cell))//日期类型
                                     {
                                         dataRow[j] = cell.DateCellValue;
                                     }
                                     else//其他数字类型
                                     {
                                         dataRow[j] = cell.NumericCellValue;
                                     }
                                 }
                                 else
                                 {

                                     dataRow[j] = cell.ToString();

                                 }

                             }

                         }
                         data.Rows.Add(dataRow);
                     }
                 }
                 fs.Close();
                 return data;
             }
             catch (Exception ex)
             {
                 Console.WriteLine("Exception: " + ex.Message);
                 return null;
             }
         }

在使用一段时间NPOI后，遇到一个问题.当导入大数据量Excel时,很不稳定,经常会出现内存溢出异常.

不稳定在于有时是20W行数据有时是10W行数据就内存溢出.跟踪了一段时间未发现原因所在,百度了

很多解决方案,发现都无法解决NPOI内存溢出的问题.最终还是选择放弃了NPOI转Aspose.

第三种方式：Aspose【收费】

代码如下:

  public DataTable ReadExcel()
         {
             Workbook book = new Workbook(fileName);
             //book.Open(strFileName);
             Worksheet sheet = book.Worksheets[];
             Cells cells = sheet.Cells;
             var dt = cells.ExportDataTableAsString(, , cells.MaxDataRow + , cells.MaxDataColumn + , true);
             return dt;
         }

导出（暂时未使用,所以没调试过）：

public MemoryStream Export<T>(IEnumerable<T> data) //, HttpResponse response
        {
            Workbook workbook = new Workbook();
            Worksheet sheet = (Worksheet)workbook.Worksheets[0];

            PropertyInfo[] ps = typeof(T).GetProperties();
            var colIndex = "A";

            foreach (var p in ps)
            {
                object[] objs = p.GetCustomAttributes(typeof(DescriptionAttribute), true);
                sheet.Cells[colIndex + 1].PutValue(((DescriptionAttribute)objs[0]).Description);
                int i = 2;
                foreach (var d in data)
                {
                    var x = p.GetValue(d, null);
                    if (p.PropertyType.ToString().ToLower() == "system.datetime")
                    {
                        var date = (DateTime)x;
                        sheet.Cells[colIndex + i].PutValue(DateTime.Parse(x.ToString()));

                        Style style = sheet.Cells[colIndex + i].GetStyle();
                        style.Number = 14;
                        sheet.Cells[colIndex + i].SetStyle(style);
                    }
                    else
                    {
                        sheet.Cells[colIndex + i].PutValue(x);
                    }

                    i++;
                }

                colIndex = ((char)(colIndex[0] + 1)).ToString();
            }
            MemoryStream ms = new MemoryStream();
            //导出格式设置xlsx xls
            workbook.Save(ms, new OoxmlSaveOptions(SaveFormat.Xlsx));
            return ms;
            //response.Clear();
            //response.Buffer = true;
            //response.Charset = "utf-8";
            //response.AppendHeader("Content-Disposition", "attachment;filename=xxx.xls");
            //response.ContentEncoding = System.Text.Encoding.UTF8;
            //response.ContentType = "application/ms-excel";
            //response.BinaryWrite(workbook.SaveToStream().ToArray());
            //response.End();
        }

　　

public ActionResult ExportExcel(string ids)
        {
            ExcelHelper helper = new ExcelHelper("导出数据");
            HttpResponse response;
            if (ids.Contains(','))
            {
                var idArr = ids.Split(',');
                try
                {
                    var idList = Array.ConvertAll(idArr, new Converter<string, int>(StrToInt)).ToList();
                    var ests = estSvc.Query(c => (idList.Contains(c.ID))).ToList();
                    List<ExportModel> exportData = new List<ExportModel>();
                    foreach (var i in ests)
                    {
                        var m = new ExportModel();
                        m.Type = i.EstateType == 0 ? "" : dicList.Find(d => d.ID == i.EstateType).Value;
                        m.RegisteDate = i.RegisteDate;
                        m.EstateName = i.EstateName;
                        m.Dept = i.AffilicatedDept;
                        m.Register = i.RegisterName;
                        m.OperateTeam = i.EstateType == 43 || i.EstateType == 44 ? i.OperateTeamChannel : i.OperateTeamProxy;
                        exportData.Add(m);

                    }
                    var s = helper.Export<ExportModel>((IEnumerable<ExportModel>)exportData);
                    Response.Clear();
                    Response.Buffer = true;
                    Response.Charset = "utf-8";
                    Response.AppendHeader("Content-Disposition", "attachment;filename=导出盘源信息.xlsx");
                    Response.ContentEncoding = System.Text.Encoding.UTF8;
                    Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                    Response.BinaryWrite(s.ToArray());
                    Response.End();
                    return null;
                }
                catch (Exception e)
                {
                    return null;
                }
            }
            else
            {
                var ests = estSvc.Query(c => c.ID == Convert.ToInt32(ids)).ToList();
                List<ExportModel> exportData = new List<ExportModel>();
                foreach (var i in ests)
                {
                    var m = new ExportModel();
                    m.Type = i.EstateType == 0 ? "" : dicList.Find(d => d.ID == i.EstateType).Value;
                    m.RegisteDate = i.RegisteDate;
                    m.EstateName = i.EstateName;
                    m.Dept = i.AffilicatedDept;
                    m.Register = i.RegisterName;
                    m.OperateTeam = i.EstateType == 43 || i.EstateType == 44 ? i.OperateTeamChannel : i.OperateTeamProxy;
                    exportData.Add(m);

                }
                var s = helper.Export<ExportModel>((IEnumerable<ExportModel>)exportData);
                Response.Clear();
                Response.Buffer = true;
                Response.Charset = "utf-8";
                Response.AppendHeader("Content-Disposition", "attachment;filename=导出盘源信息.xlsx");
                Response.ContentEncoding = System.Text.Encoding.UTF8;
                Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                Response.BinaryWrite(s.ToArray());
                Response.End();
                return null;
            }
        }