使用NPOI库导入导出EXCEL

/// <summary>
/// NPOI 导入excel
/// </summary>
/// <returns></returns>
[HttpPost]
public ActionResult NPOIInport()
{
bool isok = false;
string msg = string.Empty;
var file = Request.Files["Importexcelfile"];//接收的文件对象
var filename = SaveUploadExcel(file);//将文件保存至某一路径下 并形成新的文件名称
var filePath=System.Configuration.ConfigurationManager.AppSettings["Upload"] + @"\excel\" + filename;//新路径
IWorkbook workbook = null; //定义工作簿接口
ISheet sheet=null;//定义sheet表
DataTable data = new DataTable();
FileStream filestream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
if (file.ContentLength>0)
{
if (filePath.IndexOf(".xlsx") > 0)
{
workbook = new XSSFWorkbook(filestream);//.xlsx 文件
}
else
{
workbook = new HSSFWorkbook(filestream);//.xls文件
}
sheet = workbook.GetSheetAt(0);//默认第一个sheet sheet 下标
//sheet = workbook.GetSheet("sheet的名字");//获取想要查询sheet的名字
if (sheet!=null)
{
for (int i = 0; i < sheet.LastRowNum; i++)
{
IRow row = sheet.GetRow(i);//获取第一行 一般都是表头
var firstvalue = row.GetCell(0);//第一行的第一列
var secondvalue = row.GetCell(1);
}
//常见读取excel 已经够用  实际项目中会遇到 再次封装数据形成table  一般这个帮助类会叫**Helper
IRow firstrow = sheet.GetRow(0);
int cellcount = firstrow.LastCellNum;//总列数
for (int i = firstrow.FirstCellNum; i < cellcount; i++)
{
ICell icell = firstrow.GetCell(i);
if (icell!=null)
{
string cellvalue = icell.StringCellValue;//获取当前单元格的value
DataColumn column = new DataColumn(cellvalue);
data.Columns.Add(column);//添加表头
}
}
int startrow = sheet.FirstRowNum + 1;
for (int i = startrow; i < sheet.LastRowNum; i++)
{
IRow row = sheet.GetRow(i);
if (row!=null)
{
DataRow datarow = data.NewRow();
for (int j = row.FirstCellNum; j < cellcount; j++)
{
if (row.GetCell(j)!=null)
{
datarow[j] = row.GetCell(j).ToString();
}
}
data.Rows.Add(datarow);
}
}
//return data;
}

}
return Json(new { Isok = isok, Msg = msg });
}
public static string SaveUploadExcel(HttpPostedFileBase fileexcel)
{
string filename = fileexcel.FileName;
string extension = Path.GetExtension(filename);
int filesize = fileexcel.ContentLength;
if (filesize>int.Parse(System.Configuration.ConfigurationManager.AppSettings["UploadFileSize"]))
{
return "文件超过上限";
}
string dirPath = System.Configuration.ConfigurationManager.AppSettings["Upload"] + @"\excel\";
//生成新的文件名
string newFileName = string.Format("{0}{1}", DateTime.Now.ToString("yyMMddHHmmssfffffff"), extension);

if (!Directory.Exists(dirPath))
Directory.CreateDirectory(dirPath);
fileexcel.SaveAs(dirPath + newFileName);
//返回新生成的文件名称
return newFileName;
}