一、根據模板匯出excel資料

//模板路徑

string path = “D:\\xxxx.xlsx”;

IWorkbook workbook = null;

//用workbook 以流的形式開啟模板excel檔案

using (FileStream file = new FileStream(path, FileMode.Open, FileAccess.Read))
{
workbook = new XSSFWorkbook(file);
}

ISheet sheet = workbook.GetSheetAt(0);
IRow row = null;
MemoryStream ms = new MemoryStream();
for (int i = 2; i < list.Count + 2; i++)
{
row = sheet.CreateRow(i);
row.CreateCell(0).SetCellValue((i - 1).ToString());
}
workbook.Write(ms);
ms.Flush();
ms.Seek(0, SeekOrigin.Begin);
return File(ms, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", name + ".xlsx");

二、匯出

HSSFWorkbook workbook = new HSSFWorkbook();
     HSSFSheet sheet = workbook.CreateSheet();
 
     //填充表頭
     HSSFRow dataRow = sheet.CreateRow(0);
     foreach (DataColumn column in dtSource.Columns)
     {
         dataRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
     }
 
 
     //填充內容
     for (int i = 0; i < dtSource.Rows.Count; i++)
     {
         dataRow = sheet.CreateRow(i + 1);
         for (int j = 0; j < dtSource.Columns.Count; j++)
         {
             dataRow.CreateCell(j).SetCellValue(dtSource.Rows[i][j].ToString());
         }
     }
　　　 MemoryStream ms = new MemoryStream();
　　　　workbook.Write(ms);
　　　　ms.Flush();
　　　　ms.Seek(0, SeekOrigin.Begin);
　　　　return File(ms, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", name + ".xlsx");

三、匯入

/// <summary>
/// 讀取excel表格中的資料,將Excel檔案流轉化為dataTable資料來源
/// 預設第一行為標題
/// </summary>
/// <param name="stream">excel文件檔案流</param>
/// <param name="fileType">文件格式</param>
/// <param name="isSuccess">是否轉化成功</param>
/// <param name="resultMsg">轉換結果訊息</param>
/// <returns></returns>
public DataTable ExcelToDataTable(Stream stream, string fileType, out bool isSuccess, out string resultMsg)
{
isSuccess = false;
resultMsg = "Excel檔案流成功轉化為DataTable資料來源";
var excelToDataTable = new DataTable();

try
{
//Workbook物件代表一個工作簿,首先定義一個Excel工作薄
IWorkbook workbook;

//XSSFWorkbook 適用XLSX格式，HSSFWorkbook 適用XLS格式

#region 判斷Excel版本

switch (fileType)
{
//.XLSX是07版(或者07以上的)的Office Excel
case ".xlsx":
workbook = new XSSFWorkbook(stream);
break;
//.XLS是03版的Office Excel
case ".xls":
workbook = new HSSFWorkbook(stream);
break;

default:
throw new Exception("Excel文件格式有誤");
}

#endregion 判斷Excel版本

var sheet = workbook.GetSheetAt(0);
var rows = sheet.GetRowEnumerator();

var headerRow = sheet.GetRow(0);
int cellCount = headerRow.LastCellNum;//最後一行列數（即為總列數）

//獲取第一行標題列資料來源,轉換為dataTable資料來源的表格標題名稱
for (var j = 0; j < cellCount; j++)
{
var cell = headerRow.GetCell(j);
excelToDataTable.Columns.Add(cell.ToString());
}

//獲取Excel表格中除標題以為的所有資料來源，轉化為dataTable中的表格資料來源
for (var i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
{
var dataRow = excelToDataTable.NewRow();

var row = sheet.GetRow(i);

if (row == null) continue; //沒有資料的行預設是null　

for (int j = row.FirstCellNum; j < cellCount; j++)
{
if (row.GetCell(j) != null)//單元格內容非空驗證
{
#region NPOI獲取Excel單元格中不同型別的資料

//獲取指定的單元格資訊
var cell = row.GetCell(j);
switch (cell.CellType)
{
//首先在NPOI中數字和日期都屬於Numeric型別
//通過NPOI中自帶的DateUtil.IsCellDateFormatted判斷是否為時間日期型別
case CellType.Numeric when DateUtil.IsCellDateFormatted(cell):
dataRow[j] = cell.DateCellValue;
break;

case CellType.Numeric:
//其他數字型別
dataRow[j] = cell.NumericCellValue;
break;
//空資料型別
case CellType.Blank:
dataRow[j] = "";
break;
//公式型別
case CellType.Formula:
{
if (fileType == ".xls")
{
cell.SetCellType(CellType.String);
dataRow[j] = cell.StringCellValue;
//HSSFFormulaEvaluator eva = new HSSFFormulaEvaluator(workbook);
//dataRow[j] = eva.Evaluate(cell).StringValue;
break;
}
else
{
cell.SetCellType(CellType.String);
//XSSFFormulaEvaluator eva = new XSSFFormulaEvaluator(workbook);
dataRow[j] = cell.StringCellValue;
break;
}
}
//布林型別
case CellType.Boolean:
dataRow[j] = row.GetCell(j).BooleanCellValue;
break;
//錯誤
case CellType.Error:
dataRow[j] = row.GetCell(j).ErrorCellValue;
break;
//其他型別都按字串型別來處理（未知型別CellType.Unknown，字串型別CellType.String）
default:
dataRow[j] = cell.StringCellValue;
break;
}

#endregion NPOI獲取Excel單元格中不同型別的資料
}
}
excelToDataTable.Rows.Add(dataRow);
}

isSuccess = true;
}
catch (Exception e)
{
resultMsg = e.Message;
}

return excelToDataTable;
}