using Excel = Microsoft.Office.Interop.Excel;

public class ExcelReader
{
    public static void ReadExcelFile()
    {
        // 1. 打開文件對(duì)話框
        OpenFileDialog openFileDialog = new OpenFileDialog
        {
            Filter = "Excel 文件 (*.xls, *.xlsx)|*.xls;*.xlsx",
            Title = "請(qǐng)選擇Excel文件"
        };

        if (openFileDialog.ShowDialog() != DialogResult.OK) return;

        string filePath = openFileDialog.FileName;

        // 2. 創(chuàng)建Excel應(yīng)用實(shí)例
        Excel.Application excelApp = new Excel.Application();
        Excel.Workbook workbook = null;
        Excel.Worksheet worksheet = null;

        try
        {
            // 3. 打開工作簿
            workbook = excelApp.Workbooks.Open(filePath);
            worksheet = workbook.Sheets[1]; // 默認(rèn)讀取第一個(gè)工作表

            // 4. 獲取已使用范圍
            Excel.Range range = worksheet.UsedRange;

            // 5. 遍歷單元格
            for (int row = 1; row <= range.Rows.Count; row++)
            {
                for (int col = 1; col <= range.Columns.Count; col++)
                {
                    // 6. 讀取單元格值
                    object cellValue = range.Cells[row, col].Value2;
                    Console.Write(cellValue?.ToString() ?? "NULL" + "\t");
                }
                Console.WriteLine();
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("讀取失?。? + ex.Message);
        }
        finally
        {
            // 7. 釋放COM對(duì)象（非常重要！）
            if (workbook != null) workbook.Close(false);
            if (excelApp != null) excelApp.Quit();
            ReleaseComObject(worksheet);
            ReleaseComObject(workbook);
            ReleaseComObject(excelApp);
        }
    }

    private static void ReleaseComObject(object obj)
    {
        if (obj != null) System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
    }
}

Install-Package EPPlus

using OfficeOpenXml;
using System.IO;

public class EpplusReader
{
    public static void ReadExcelFile()
    {
        OpenFileDialog openFileDialog = new OpenFileDialog
        {
            Filter = "Excel 文件 (*.xlsx)|*.xlsx",
            Title = "請(qǐng)選擇Excel文件"
        };

        if (openFileDialog.ShowDialog() != DialogResult.OK) return;

        string filePath = openFileDialog.FileName;

        using (var package = new ExcelPackage(new FileInfo(filePath)))
        {
            // 1. 獲取第一個(gè)工作表
            ExcelWorksheet worksheet = package.Workbook.Worksheets[0];

            int rowCount = worksheet.Dimension.Rows;
            int colCount = worksheet.Dimension.Columns;

            // 2. 遍歷單元格
            for (int row = 1; row <= rowCount; row++)
            {
                for (int col = 1; col <= colCount; col++)
                {
                    // 3. 讀取單元格值
                    string cellValue = worksheet.Cells[row, col].Text;
                    Console.Write(cellValue + "\t");
                }
                Console.WriteLine();
            }
        }
    }
}

Install-Package NPOI

using NPOI.HSSF.UserModel;
using NPOI.XSSF.UserModel;
using NPOI.SS.UserModel;

public class NpoiReader
{
    public static void ReadExcelFile()
    {
        OpenFileDialog openFileDialog = new OpenFileDialog
        {
            Filter = "Excel 文件 (*.xls, *.xlsx)|*.xls;*.xlsx",
            Title = "請(qǐng)選擇Excel文件"
        };

        if (openFileDialog.ShowDialog() != DialogResult.OK) return;

        string filePath = openFileDialog.FileName;

        IWorkbook workbook = null;

        using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        {
            // 1. 根據(jù)文件擴(kuò)展名選擇加載器
            if (filePath.EndsWith(".xls"))
            {
                workbook = new HSSFWorkbook(file); // .xls格式
            }
            else if (filePath.EndsWith(".xlsx"))
            {
                workbook = new XSSFWorkbook(file); // .xlsx格式
            }
        }

        if (workbook == null) return;

        ISheet sheet = workbook.GetSheetAt(0); // 獲取第一個(gè)工作表

        // 2. 遍歷行
        for (int rowIndex = 0; rowIndex <= sheet.LastRowNum; rowIndex++)
        {
            IRow row = sheet.GetRow(rowIndex);
            if (row == null) continue;

            // 3. 遍歷單元格
            for (int colIndex = 0; colIndex < row.LastCellNum; colIndex++)
            {
                ICell cell = row.GetCell(colIndex);
                string cellValue = cell?.ToString() ?? "NULL";
                Console.Write(cellValue + "\t");
            }
            Console.WriteLine();
        }
    }
}

// 在finally塊中強(qiáng)制退出
if (excelApp != null)
{
    excelApp.Quit();
    ReleaseComObject(excelApp);
}

if (!File.Exists(filePath))
{
    MessageBox.Show("文件不存在！");
    return;
}

try
{
    workbook = excelApp.Workbooks.Open(filePath);
}
catch (Exception ex)
{
    MessageBox.Show("文件被占用，請(qǐng)關(guān)閉Excel后再試！");
}

private void ImportToDataGridView(string filePath)
{
    dataGridView1.Rows.Clear();
    dataGridView1.Columns.Clear();

    using (var package = new ExcelPackage(new FileInfo(filePath)))
    {
        var worksheet = package.Workbook.Worksheets[0];
        int colCount = worksheet.Dimension.Columns;

        // 添加列頭
        for (int col = 1; col <= colCount; col++)
        {
            dataGridView1.Columns.Add(new DataGridViewTextBoxColumn
            {
                HeaderText = worksheet.Cells[1, col].Text
            });
        }

        // 添加數(shù)據(jù)行
        for (int row = 2; row <= worksheet.Dimension.Rows; row++)
        {
            var cells = new List<string>();
            for (int col = 1; col <= colCount; col++)
            {
                cells.Add(worksheet.Cells[row, col].Text);
            }
            dataGridView1.Rows.Add(cells.ToArray());
        }
    }
}