// 讀取xlsx
private void ReadExcelFiles(string folderPath)
{
    if (!Directory.Exists(folderPath))
    {
        MessageBox.Show("指定的文件夾路徑不存在");
        return;
    }
    
    // ===創(chuàng)建一個(gè)新的工作簿===
    IWorkbook workbook = new XSSFWorkbook();
    ISheet sheet = workbook.CreateSheet("Sheet1");

    // 定義表頭
    string[] headers = {
        "字段1", "字段2", "字段3", "字段4", "字段5"
    };

    // 創(chuàng)建表頭行
    IRow headerRow = sheet.CreateRow(0);
    for (int i = 0; i < headers.Length; i++)
    {
        headerRow.CreateCell(i).SetCellValue(headers[i]);
    }
    // ===創(chuàng)建一個(gè)新的工作簿===


    int rowIndex = 1;
    var files = Directory.GetFiles(folderPath, "*.xlsx");
    foreach (var file in files)
    {
        try
        {
            if (!File.Exists(file))
            {
                MessageBox.Show($"文件 {file} 不存在");
                continue;
            }

            using (var fileStream = new FileStream(file, FileMode.Open, FileAccess.Read))
            {
                IWorkbook workbook2 = new XSSFWorkbook(fileStream);
                ISheet sheet2 = workbook2.GetSheetAt(0); // 獲取第一個(gè)工作表

                // 獲取行數(shù)
                int rowCount = sheet2.PhysicalNumberOfRows;
                for (int rr = 0; rr < rowCount; rr++)
                {
                    IRow row = sheet2.GetRow(rr + 1); // 獲取第二行

                    if (row != null)
                    {
                        var rowValues = row.Cells.Select(cell => cell.ToString()).ToArray();

                        IRow dataRow = sheet.CreateRow(rowIndex);
                        for (int i = 0; i < rowValues.Length; i++)
                        {
                            dataRow.CreateCell(i).SetCellValue(rowValues[i]);
                        }
                    }

                    rowIndex++;
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show($"讀取文件 {Path.GetFileName(file)} 時(shí)發(fā)生錯(cuò)誤: {ex.Message}");
        }
    }

    // ===保存文件===
    string filePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "alldata.xlsx");
    using (var fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))
    {
        workbook.Write(fs);
    }
    // ===/保存文件===
}

using System;
using System.IO;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;  // 對(duì)于 .xlsx 格式
// using NPOI.HSSF.UserModel;  // 對(duì)于 .xls 格式

class Program
{
    static void Main()
    {
        string filePath = "your_file_path.xlsx";
        
        using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        {
            IWorkbook workbook = new XSSFWorkbook(fileStream);  // 對(duì)于 .xlsx 文件
            ISheet sheet = workbook.GetSheetAt(0);
            foreach (IRow row in sheet)
            {
                foreach (ICell cell in row)
                {
                    Console.Write($"{cell.ToString()} ");
                }
                Console.WriteLine();
            }
        }
    }
}

using System;
using System.IO;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;  // 對(duì)于 .xlsx 格式
// using NPOI.HSSF.UserModel;  // 對(duì)于 .xls 格式

class Program
{
    static void Main()
    {
        string filePath = "your_file_path.xlsx";
        
        IWorkbook workbook = new XSSFWorkbook();
        ISheet sheet = workbook.CreateSheet("Sheet1");
        
        IRow row = sheet.CreateRow(0);
        ICell cell = row.CreateCell(0);
        cell.SetCellValue("Hello, NPOI!");
        
        using (FileStream fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write))
        {
            workbook.Write(fileStream);
        }
    }
}