1. ติดตั้ง Package NPOI Version 2.4.1
2. อ่านไฟล์ Excel

1.ติดตั้ง Package NPOI Version 2.4.1

PM> Install-Package NPOI -Version 2.4.1

2.อ่านไฟล์ Excel

อ่าน Sheet1 แถวแรก คอลัมน์แรก

using NPOI.SS.UserModel;
using System;
using System.Globalization;
using System.IO;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string filename = @"Workbook1.xlsx";
            using (var fileData = new FileStream(filename, FileMode.Open))
            {
                ExcelFileReader excelFileReader = new ExcelFileReader();
                excelFileReader.InitializeMembers(fileData);
                ISheet sheet1 = excelFileReader.workbook.GetSheet("Sheet1");
                IRow row0 = sheet1.GetRow(0);
                ICell cell0 = row0.GetCell(0);
                string text = cell0.StringCellValue;
                Console.WriteLine(text);
            }

            Console.WriteLine("OK");
        }

        //
        // ExcelFileReader
        //
        public class ExcelFileReader
        {
            public IWorkbook workbook;
            public DataFormatter dataFormatter;
            public IFormulaEvaluator formulaEvaluator;

            //
            // Initialize from a stream of Excel file
            //
            public void InitializeMembers(Stream excelFileStream)
            {
                this.workbook = WorkbookFactory.Create(excelFileStream);
                if (this.workbook != null)
                {
                    this.dataFormatter = new DataFormatter(CultureInfo.InvariantCulture);
                    this.formulaEvaluator = WorkbookFactory.CreateFormulaEvaluator(this.workbook);
                }
            }

            //
            // Get formatted value as string from the specified cell
            //
            public string GetFormattedValue(ICell cell)
            {
                string returnValue = string.Empty;
                if (cell != null)
                {
                    try
                    {
                        // Get evaluated and formatted cell value
                        returnValue = this.dataFormatter.FormatCellValue(cell, this.formulaEvaluator);
                    }
                    catch
                    {
                        // When failed in evaluating the formula, use stored values instead...
                        // and set cell value for reference from formulae in other cells...
                        if (cell.CellType == CellType.Formula)
                        {
                            switch (cell.CachedFormulaResultType)
                            {
                                case CellType.String:
                                    returnValue = cell.StringCellValue;
                                    cell.SetCellValue(cell.StringCellValue);
                                    break;
                                case CellType.Numeric:
                                    returnValue = dataFormatter.FormatRawCellContents(cell.NumericCellValue, 0, cell.CellStyle.GetDataFormatString());
                                    cell.SetCellValue(cell.NumericCellValue);
                                    break;
                                case CellType.Boolean:
                                    returnValue = cell.BooleanCellValue.ToString();
                                    cell.SetCellValue(cell.BooleanCellValue);
                                    break;
                                default:
                                    break;
                            }
                        }
                    }
                }

                return (returnValue ?? string.Empty).Trim();
            }

            //
            // Get unformatted value as string from the specified cell
            //
            public string GetUnformattedValue(ICell cell)
            {
                string returnValue = string.Empty;
                if (cell != null)
                {
                    try
                    {
                        // Get evaluated cell value
                        returnValue = (cell.CellType == CellType.Numeric ||
                        (cell.CellType == CellType.Formula &&
                        cell.CachedFormulaResultType == CellType.Numeric)) ?
                            formulaEvaluator.EvaluateInCell(cell).NumericCellValue.ToString() :
                            this.dataFormatter.FormatCellValue(cell, this.formulaEvaluator);
                    }
                    catch
                    {
                        // When failed in evaluating the formula, use stored values instead...
                        // and set cell value for reference from formulae in other cells...
                        if (cell.CellType == CellType.Formula)
                        {
                            switch (cell.CachedFormulaResultType)
                            {
                                case CellType.String:
                                    returnValue = cell.StringCellValue;
                                    cell.SetCellValue(cell.StringCellValue);
                                    break;
                                case CellType.Numeric:
                                    returnValue = cell.NumericCellValue.ToString();
                                    cell.SetCellValue(cell.NumericCellValue);
                                    break;
                                case CellType.Boolean:
                                    returnValue = cell.BooleanCellValue.ToString();
                                    cell.SetCellValue(cell.BooleanCellValue);
                                    break;
                                default:
                                    break;
                            }
                        }
                    }
                }

                return (returnValue ?? string.Empty).Trim();
            }
        }
    }
}

Link

• Read Excel using NPOI