How to read file using NPOI
Simple read example below:
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
//.....
private void button1_Click(object sender, EventArgs e)
{
HSSFWorkbook hssfwb;
using (FileStream file = new FileStream(@"c:\test.xls", FileMode.Open, FileAccess.Read))
{
hssfwb= new HSSFWorkbook(file);
}
ISheet sheet = hssfwb.GetSheet("Arkusz1");
for (int row = 0; row <= sheet.LastRowNum; row++)
{
if (sheet.GetRow(row) != null) //null is when the row only contains empty cells
{
MessageBox.Show(string.Format("Row {0} = {1}", row, sheet.GetRow(row).GetCell(0).StringCellValue));
}
}
}
By the way: on NPOI website here in Download section there is example package - a pack of C# examples. Try it, if you haven't yet. :)
I find NPOI very usefull for working with Excel Files, here is my implementation (Comments are in Spanish, sorry for that):
This Method Opens an Excel (both xls or xlsx) file and converts it into a DataTable.
/// <summary>Abre un archivo de Excel (xls o xlsx) y lo convierte en un DataTable.
/// LA PRIMERA FILA DEBE CONTENER LOS NOMBRES DE LOS CAMPOS.</summary>
/// <param name="pRutaArchivo">Ruta completa del archivo a abrir.</param>
/// <param name="pHojaIndex">Número (basado en cero) de la hoja que se desea abrir. 0 es la primera hoja.</param>
private DataTable Excel_To_DataTable(string pRutaArchivo, int pHojaIndex)
{
// --------------------------------- //
/* REFERENCIAS:
* NPOI.dll
* NPOI.OOXML.dll
* NPOI.OpenXml4Net.dll */
// --------------------------------- //
/* USING:
* using NPOI.SS.UserModel;
* using NPOI.HSSF.UserModel;
* using NPOI.XSSF.UserModel; */
// AUTOR: Ing. Jhollman Chacon R. 2015
// --------------------------------- //
DataTable Tabla = null;
try
{
if (System.IO.File.Exists(pRutaArchivo))
{
IWorkbook workbook = null; //IWorkbook determina si es xls o xlsx
ISheet worksheet = null;
string first_sheet_name = "";
using (FileStream FS = new FileStream(pRutaArchivo, FileMode.Open, FileAccess.Read))
{
workbook = WorkbookFactory.Create(FS); //Abre tanto XLS como XLSX
worksheet = workbook.GetSheetAt(pHojaIndex); //Obtener Hoja por indice
first_sheet_name = worksheet.SheetName; //Obtener el nombre de la Hoja
Tabla = new DataTable(first_sheet_name);
Tabla.Rows.Clear();
Tabla.Columns.Clear();
// Leer Fila por fila desde la primera
for (int rowIndex = 0; rowIndex <= worksheet.LastRowNum; rowIndex++)
{
DataRow NewReg = null;
IRow row = worksheet.GetRow(rowIndex);
IRow row2 = null;
IRow row3 = null;
if (rowIndex == 0)
{
row2 = worksheet.GetRow(rowIndex + 1); //Si es la Primera fila, obtengo tambien la segunda para saber el tipo de datos
row3 = worksheet.GetRow(rowIndex + 2); //Y la tercera tambien por las dudas
}
if (row != null) //null is when the row only contains empty cells
{
if (rowIndex > 0) NewReg = Tabla.NewRow();
int colIndex = 0;
//Leer cada Columna de la fila
foreach (ICell cell in row.Cells)
{
object valorCell = null;
string cellType = "";
string[] cellType2 = new string[2];
if (rowIndex == 0) //Asumo que la primera fila contiene los titlos:
{
for (int i = 0; i < 2; i++)
{
ICell cell2 = null;
if (i == 0) { cell2 = row2.GetCell(cell.ColumnIndex); }
else { cell2 = row3.GetCell(cell.ColumnIndex); }
if (cell2 != null)
{
switch (cell2.CellType)
{
case CellType.Blank: break;
case CellType.Boolean: cellType2[i] = "System.Boolean"; break;
case CellType.String: cellType2[i] = "System.String"; break;
case CellType.Numeric:
if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType2[i] = "System.DateTime"; }
else
{
cellType2[i] = "System.Double"; //valorCell = cell2.NumericCellValue;
}
break;
case CellType.Formula:
bool continuar = true;
switch (cell2.CachedFormulaResultType)
{
case CellType.Boolean: cellType2[i] = "System.Boolean"; break;
case CellType.String: cellType2[i] = "System.String"; break;
case CellType.Numeric:
if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType2[i] = "System.DateTime"; }
else
{
try
{
//DETERMINAR SI ES BOOLEANO
if (cell2.CellFormula == "TRUE()") { cellType2[i] = "System.Boolean"; continuar = false; }
if (continuar && cell2.CellFormula == "FALSE()") { cellType2[i] = "System.Boolean"; continuar = false; }
if (continuar) { cellType2[i] = "System.Double"; continuar = false; }
}
catch { }
} break;
}
break;
default:
cellType2[i] = "System.String"; break;
}
}
}
//Resolver las diferencias de Tipos
if (cellType2[0] == cellType2[1]) { cellType = cellType2[0]; }
else
{
if (cellType2[0] == null) cellType = cellType2[1];
if (cellType2[1] == null) cellType = cellType2[0];
if (cellType == "") cellType = "System.String";
}
//Obtener el nombre de la Columna
string colName = "Column_{0}";
try { colName = cell.StringCellValue; }
catch { colName = string.Format(colName, colIndex); }
//Verificar que NO se repita el Nombre de la Columna
foreach (DataColumn col in Tabla.Columns)
{
if (col.ColumnName == colName) colName = string.Format("{0}_{1}", colName, colIndex);
}
//Agregar el campos de la tabla:
DataColumn codigo = new DataColumn(colName, System.Type.GetType(cellType));
Tabla.Columns.Add(codigo); colIndex++;
}
else
{
//Las demas filas son registros:
switch (cell.CellType)
{
case CellType.Blank: valorCell = DBNull.Value; break;
case CellType.Boolean: valorCell = cell.BooleanCellValue; break;
case CellType.String: valorCell = cell.StringCellValue; break;
case CellType.Numeric:
if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; }
else { valorCell = cell.NumericCellValue; } break;
case CellType.Formula:
switch (cell.CachedFormulaResultType)
{
case CellType.Blank: valorCell = DBNull.Value; break;
case CellType.String: valorCell = cell.StringCellValue; break;
case CellType.Boolean: valorCell = cell.BooleanCellValue; break;
case CellType.Numeric:
if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; }
else { valorCell = cell.NumericCellValue; }
break;
}
break;
default: valorCell = cell.StringCellValue; break;
}
//Agregar el nuevo Registro
if (cell.ColumnIndex <= Tabla.Columns.Count - 1) NewReg[cell.ColumnIndex] = valorCell;
}
}
}
if (rowIndex > 0) Tabla.Rows.Add(NewReg);
}
Tabla.AcceptChanges();
}
}
else
{
throw new Exception("ERROR 404: El archivo especificado NO existe.");
}
}
catch (Exception ex)
{
throw ex;
}
return Tabla;
}
This Second method does the oposite, saves a DataTable into an Excel File, yeah it can either be xls or the new xlsx, your choise!
/// <summary>Convierte un DataTable en un archivo de Excel (xls o Xlsx) y lo guarda en disco.</summary>
/// <param name="pDatos">Datos de la Tabla a guardar. Usa el nombre de la tabla como nombre de la Hoja</param>
/// <param name="pFilePath">Ruta del archivo donde se guarda.</param>
private void DataTable_To_Excel(DataTable pDatos, string pFilePath)
{
try
{
if (pDatos != null && pDatos.Rows.Count > 0)
{
IWorkbook workbook = null;
ISheet worksheet = null;
using (FileStream stream = new FileStream(pFilePath, FileMode.Create, FileAccess.ReadWrite))
{
string Ext = System.IO.Path.GetExtension(pFilePath); //<-Extension del archivo
switch (Ext.ToLower())
{
case ".xls":
HSSFWorkbook workbookH = new HSSFWorkbook();
NPOI.HPSF.DocumentSummaryInformation dsi = NPOI.HPSF.PropertySetFactory.CreateDocumentSummaryInformation();
dsi.Company = "Cutcsa"; dsi.Manager = "Departamento Informatico";
workbookH.DocumentSummaryInformation = dsi;
workbook = workbookH;
break;
case ".xlsx": workbook = new XSSFWorkbook(); break;
}
worksheet = workbook.CreateSheet(pDatos.TableName); //<-Usa el nombre de la tabla como nombre de la Hoja
//CREAR EN LA PRIMERA FILA LOS TITULOS DE LAS COLUMNAS
int iRow = 0;
if (pDatos.Columns.Count > 0)
{
int iCol = 0;
IRow fila = worksheet.CreateRow(iRow);
foreach (DataColumn columna in pDatos.Columns)
{
ICell cell = fila.CreateCell(iCol, CellType.String);
cell.SetCellValue(columna.ColumnName);
iCol++;
}
iRow++;
}
//FORMATOS PARA CIERTOS TIPOS DE DATOS
ICellStyle _doubleCellStyle = workbook.CreateCellStyle();
_doubleCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("#,##0.###");
ICellStyle _intCellStyle = workbook.CreateCellStyle();
_intCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("#,##0");
ICellStyle _boolCellStyle = workbook.CreateCellStyle();
_boolCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("BOOLEAN");
ICellStyle _dateCellStyle = workbook.CreateCellStyle();
_dateCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("dd-MM-yyyy");
ICellStyle _dateTimeCellStyle = workbook.CreateCellStyle();
_dateTimeCellStyle.DataFormat = workbook.CreateDataFormat().GetFormat("dd-MM-yyyy HH:mm:ss");
//AHORA CREAR UNA FILA POR CADA REGISTRO DE LA TABLA
foreach (DataRow row in pDatos.Rows)
{
IRow fila = worksheet.CreateRow(iRow);
int iCol = 0;
foreach (DataColumn column in pDatos.Columns)
{
ICell cell = null; //<-Representa la celda actual
object cellValue = row[iCol]; //<- El valor actual de la celda
switch (column.DataType.ToString())
{
case "System.Boolean":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Boolean);
if (Convert.ToBoolean(cellValue)) { cell.SetCellFormula("TRUE()"); }
else { cell.SetCellFormula("FALSE()"); }
cell.CellStyle = _boolCellStyle;
}
break;
case "System.String":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.String);
cell.SetCellValue(Convert.ToString(cellValue));
}
break;
case "System.Int32":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Numeric);
cell.SetCellValue(Convert.ToInt32(cellValue));
cell.CellStyle = _intCellStyle;
}
break;
case "System.Int64":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Numeric);
cell.SetCellValue(Convert.ToInt64(cellValue));
cell.CellStyle = _intCellStyle;
}
break;
case "System.Decimal":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Numeric);
cell.SetCellValue(Convert.ToDouble(cellValue));
cell.CellStyle = _doubleCellStyle;
}
break;
case "System.Double":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Numeric);
cell.SetCellValue(Convert.ToDouble(cellValue));
cell.CellStyle = _doubleCellStyle;
}
break;
case "System.DateTime":
if (cellValue != DBNull.Value)
{
cell = fila.CreateCell(iCol, CellType.Numeric);
cell.SetCellValue(Convert.ToDateTime(cellValue));
//Si No tiene valor de Hora, usar formato dd-MM-yyyy
DateTime cDate = Convert.ToDateTime(cellValue);
if (cDate != null && cDate.Hour > 0) { cell.CellStyle = _dateTimeCellStyle; }
else { cell.CellStyle = _dateCellStyle; }
}
break;
default:
break;
}
iCol++;
}
iRow++;
}
workbook.Write(stream);
stream.Close();
}
}
}
catch (Exception ex)
{
throw ex;
}
}
With this 2 methods you can Open an Excel file, load it into a DataTable, do your modifications and save it back into an Excel file.
Hope you guys find this usefull.
It might be helpful to rely on the Workbook factory to instantiate the workbook object since the factory method will do the detection of xls or xlsx for you. Reference: http://apache-poi.1045710.n5.nabble.com/How-to-check-for-valid-excel-files-using-POI-without-checking-the-file-extension-td2341055.html
IWorkbook workbook = WorkbookFactory.Create(inputStream);
If you're not sure of the Sheet's name but you are sure of the index (0 based), you can grab the sheet like this:
ISheet sheet = workbook.GetSheetAt(sheetIndex);
You can then iterate through the rows using code supplied by the accepted answer from mj82