一、引言

昨天公司EDI導入功能出現問題，經排查是由於引用Com組件Microsoft.Office.Interop.Excel.dll，操作Excel引起，可是現在客戶電腦壓根都沒裝Office，還倒個鬼數據啊（畫個圈圈xx下之前寫這個功能的人），一次重構操作Excel功能之旅由此開始。。。

二、NPOI操作Excel

1.整個Excel（工作薄）：WorkBook，包含的頁（工作表）：Sheet， 行：Row， 單元格：Cell。

2.HSSFWorkbook:是操作Excel2003以前（包括2003）的版本，擴展名是.xls ；

XSSFWorkbook:是操作Excel2007及以上的版本，擴展名是.xlsx。

3.NPOI組件下載地址：https://npoi.codeplex.com/

4.如果是.NET Framwork環境，請將下載的npoi組件都引用一下，如果是.NET Core環境，就在NuGet程序包中搜索安裝 DotNetCore.NPOI 這個程序包即可

5.NPOI源碼地址：https://github.com/tonyqus/npoi

下面是NPOI讀寫Excel的例子，ExcelHelper是自己封裝的類庫，包括創建Excel，Excel寫入txt，Excel寫入DataTable，DataTable寫入Excel等

using System;
using System.Collections.Generic;
 
using System.Linq;
using System.Text;
using NPOI.HSSF.UserModel;//HSSFWorkbook
using NPOI.SS.UserModel;//ISheet
using System.IO;
using NPOI.XSSF.UserModel;
using System.Data;

namespace NetUtilityLib
{
    public class ExcelHelper
    {
        /// <summary>
        /// 基礎demo 創建默認版本的excel 
        /// </summary>
 

        /// <param name="path">需要創建的excel路徑</param>
        private static void CreateExcel(string path)
        {
            try
            {
                #region  //操作excel 03版本
                //創建工作薄
                HSSFWorkbook hssfworkbook = new HSSFWorkbook();
                hssfworkbook.CreateSheet("Sheet1");
                hssfworkbook.CreateSheet("Sheet2");
                hssfworkbook.CreateSheet("Sheet3");
                //根據名稱獲取指定Sheet頁
                ISheet sheet = hssfworkbook.GetSheet("Sheet1");
                //根據索引 創建所在行  row range 0~65535
                IRow row = sheet.CreateRow(1);
                for (int i = 0; i < 20; i++)
                {
                    ICell cell = row.CreateCell(i);//在行中創建單元格
                    cell.SetCellValue(i);//向單元格張添加數據
                }
                //打開excel文件,不存在就創建excel
                using (FileStream file = new FileStream(@"F:/test.xls", FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    //將工作薄hssfworkbook 寫入excel
                    hssfworkbook.Write(file);
                }
                #endregion
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.StackTrace);
                throw new Exception(ex.Message);
            }
        }
        /// <summary>
        /// 創建工作薄
        /// </summary>
        /// <param name="path">excel路徑</param>
        /// <param name="workbook">創建的工作薄</param>
        /// <returns>創建工作薄是否成功</returns>
        private static bool GetWorkbook(string path, out IWorkbook workbook)
        {
            if (path.IndexOf("xlsx") > 0)
            {
                workbook = new XSSFWorkbook();//07 及以上
            }
            else if (path.IndexOf("xls") > 0)
            {
                workbook = new HSSFWorkbook();//03
            }

            else
            {
                workbook = null;
                return false;
            }
            return true;
        }
        /// <summary>
        /// 讀取時 創建工作薄
        /// </summary>
        /// <param name="path">excel的路徑</param>
        /// <param name="workbook">將數據讀進工作薄</param>
        /// <param name="fs">數據流</param>
        /// <returns>數據是否能夠讀進excel中</returns>
        private static bool GetWorkbook(string path, out IWorkbook workbook, FileStream fs)
        {
            if (path.IndexOf("xlsx") > 0)
            {
                workbook = new XSSFWorkbook(fs);//07 及以上
            }
            else if (path.IndexOf("xls") > 0)
            {
                workbook = new HSSFWorkbook(fs);//03
            }

            else
            {
                workbook = null;
                return false;
            }
            return true;
        }
        /// <summary>
        /// 創建一個excel
        /// </summary>
        /// <param name="path">要創建的excel路徑及名稱</param>
        /// <param name="sheetNames">要創建的excel的sheet頁名稱集合</param>
        /// <returns>創建是否成功</returns>
        public static bool CreateExcel(string path, IList<string> sheetNames)
        {
            try
            {
                IWorkbook workbook = null;
                FileStream fs = null;
                if (!GetWorkbook(path, out workbook)) { return false; }
                if (sheetNames.Count > 0)
                {
                    foreach (string sheetName in sheetNames)
                    {
                        workbook.CreateSheet(sheetName);
                    }
                }
                else
                {
                    workbook.CreateSheet("Sheet1");
                    workbook.CreateSheet("Sheet2");
                    workbook.CreateSheet("Sheet3");
                }
                using (fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    workbook.Write(fs);
                }
                return true;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.StackTrace);
                throw new Exception(ex.Message);
            }

        }
        /// <summary>
        /// 將excel中數據導入到txt中
        /// </summary>
        /// <param name="excelPath">要導出的excel路徑及名稱</param>
        /// <param name="txtPath">要導入的txtl路徑及名稱</param>
        /// <returns>是否導入txt成功</returns>
        public static bool ExcelToTxt(string excelPath, string txtPath)
        {
            try
            {
                IWorkbook workbook = null;
                FileStream fs = null;
                object cellValue = DBNull.Value;
                StringBuilder sbr = new StringBuilder();
                using (fs = new FileStream(excelPath, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    if (!GetWorkbook(excelPath, out workbook, fs)) { return false; }
                    for (int i = 0; i < workbook.NumberOfSheets; i++)  //NumberOfSheets是excel中總共的表數
                    {
                        ISheet sheet = workbook.GetSheetAt(i);   //讀取當前表數據
                        for (int j = 0; j <= sheet.LastRowNum; j++)  //LastRowNum 是當前表的總行數
                        {
                            IRow row = sheet.GetRow(j);  //讀取當前行數據
                            if (row != null)
                            {
                                sbr.Append("\r\n");//換行
                                for (int k = 0; k <= row.LastCellNum; k++)  //LastCellNum 是當前行的總列數
                                {
                                    ICell cell = row.GetCell(k);  //當前表格
                                    if (cell != null)
                                    {
                                        cellValue = GetCellValue(cell);
                                    }
                                    sbr.Append(cellValue + "\t");   //獲取表格中的數據
                                    cellValue = DBNull.Value;
                                }
                            }
                        }
                    }
                }
                sbr.ToString();
                using (StreamWriter wr = new StreamWriter(new FileStream(txtPath, FileMode.Append)))  //把讀取excel文件的數據寫入txt文件中
                {
                    wr.Write(sbr.ToString());
                    wr.Flush();
                }
                return true;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.StackTrace);
                throw new Exception(ex.Message);
            }
        }
        /// <summary>
        /// 將excel中的數據導入到DataTable中
        /// </summary>
        /// <param name="data">要導入的excel路徑及名稱</param>
        /// <param name="sheetName">excel工作薄sheet的名稱</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public static DataTable ExcelToDataTable(string excelPath, string sheetName, bool isFirstRowColumn)
        {
            IWorkbook workbook = null;
            ISheet sheet = null;
            FileStream fs = null;
            object cellValue = DBNull.Value;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                using (fs = new FileStream(excelPath, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    if (!GetWorkbook(excelPath, out workbook, fs)) { return null; }

                    if (sheetName != null)
                    {
                        sheet = workbook.GetSheet(sheetName);
                        if (sheet == null) //如果沒有找到指定的sheetName對應的sheet，則嘗試獲取第一個sheet
                        {
                            sheet = workbook.GetSheetAt(0);
                        }
                    }
                    else
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                    if (sheet != null)
                    {
                        IRow firstRow = sheet.GetRow(0);
                        int cellCount = firstRow.LastCellNum; //一行最後一個cell的編號 即總的列數

                        if (isFirstRowColumn)
                        {
                            for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                            {
                                ICell cell = firstRow.GetCell(i);
                                if (cell != null)
                                {
                                    cellValue = GetCellValue(cell);
                                    if (cellValue != null)
                                    {
                                        DataColumn column = new DataColumn(cellValue.ToString());
                                        data.Columns.Add(column);
                                    }
                                }
                            }
                            startRow = sheet.FirstRowNum + 1;
                        }
                        else
                        {
                            for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                            {
                                DataColumn column = new DataColumn();
                                data.Columns.Add(column);
                            }
                            startRow = sheet.FirstRowNum;
                        }

                        //最後一列的標號
                        int rowCount = sheet.LastRowNum;
                        for (int i = startRow; i <= rowCount; ++i)
                        {
                            IRow row = sheet.GetRow(i);
                            if (row == null) continue; //沒有數據的行默認是null　　　　　　　

                            DataRow dataRow = data.NewRow();
                            for (int j = row.FirstCellNum; j < cellCount; ++j)
                            {
                                dataRow[j] = row.GetCell(j) == null ? DBNull.Value : GetCellValue(row.GetCell(j));
                            }
                            data.Rows.Add(dataRow);
                        }
                    }
                }
                return data;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine("Exception: " + ex.Message);
                return null;
            }
        }
        /// <summary>
        /// 將DataTable數據導入到excel中
        /// </summary>
        /// <param name="data">要導入的excel路徑及名稱</param>
        /// <param name="data">要導入的數據</param>
        /// <param name="isColumnWritten">DataTable的列名是否要導入</param>
        /// <param name="sheetName">要導入的excel的sheet的名稱</param>
        /// <returns>導入數據行數(包含列名那一行)</returns>
        public static int DataTableToExcel(string excelPath, DataTable data, string sheetName, bool isColumnWritten)
        {
            int i = 0;
            int j = 0;
            int count = 0;
            IWorkbook workbook = null;
            ISheet sheet = null;
            FileStream fs = null;

            try
            {
                using (fs = new FileStream(excelPath, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    if (!GetWorkbook(excelPath, out workbook)) { return -1; }
                    sheetName = sheetName != "" ? sheetName : "Sheet1";
                    sheet = workbook.CreateSheet(sheetName);
                    if (isColumnWritten == true) //寫入DataTable的列名
                    {
                        IRow row = sheet.CreateRow(0);
                        for (j = 0; j < data.Columns.Count; ++j)
                        {
                            row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                        }
                        count = 1;
                    }
                    else
                    {
                        count = 0;
                    }

                    for (i = 0; i < data.Rows.Count; ++i)
                    {
                        IRow row = sheet.CreateRow(count);
                        for (j = 0; j < data.Columns.Count; ++j)
                        {
                            row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                        }
                        ++count;
                    }
                    workbook.Write(fs); //寫入到excel
                    return count;
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine("Exception: " + ex.Message);
                return -1;
            }
        }
        /// <summary>
        /// 獲取excel中單元格的數據
        /// </summary>
        /// <param name="pCell">獲取到的單元格</param>
        /// <returns>單元格中數據</returns>
        private static object GetCellValue(ICell pCell)
        {
            object objReturn;
            try
            {
                switch (pCell.CellType)
                {
                    case CellType.Blank:
                        objReturn = DBNull.Value;
                        break;
                    //case CellType.Boolean:
                    //    break;
                    //case CellType.Error:
                    //    break;
                    case CellType.Formula:
                        objReturn = TryReturn(pCell);
                        break;
                    case CellType.Numeric:
                        if (pCell.CellStyle.DataFormat == 14 || pCell.CellStyle.DataFormat == 22 || pCell.CellStyle.DataFormat == 165 || pCell.CellStyle.DataFormat == 164 || pCell.CellStyle.DataFormat == 191 || pCell.CellStyle.DataFormat == 195)//14為日期類型
                        {
                            //來自Excel單元格的數據如果能轉為日期類型，則取DateCellValue 不可以則NumericCellValue
                            DateTime dtCellValue;
                            if (DateTime.TryParse(pCell.ToString(), out dtCellValue))
                            {
                                if (pCell.ToString().IndexOf(",") > -1)
                                    objReturn = pCell.NumericCellValue;
                                else
                                    objReturn = pCell.DateCellValue;
                            }
                            else
                            {
                                objReturn = pCell.NumericCellValue;
                            }
                        }
                        else
                        {
                            objReturn = pCell.NumericCellValue;
                        }
                        break;
                    case CellType.String:
                        objReturn = pCell.StringCellValue;
                        break;
                    //case CellType.Unknown:
                    //    break;
                    default:
                        objReturn = pCell.ToString();
                        break;
                }
                return objReturn;
            }
            catch (Exception)
            {
                objReturn = pCell.ToString();
            }
            return objReturn;
        }
        /// <summary>
        /// 用於容錯,當NumericCellValue出現異常時,默認取StringCellValue的值.
        /// </summary>
        /// <param name="pCell"></param>
        /// <returns></returns>
        private static object TryReturn(ICell pCell)
        {
            object objReturn;
            try
            {
                objReturn = pCell.NumericCellValue;
                return objReturn;
            }
            catch
            {
                objReturn = pCell.StringCellValue;
                return objReturn;
            }
        }
    }
}

源代碼已上傳至：https://github.com/jdzhang1221/NetUtilityLib

寫在後面：

如果你是大牛，請多多批評指正文中不足；

如果你和博主一樣是小白，請點下右下角推薦，因為你的支持是我堅持不懈的動力；

如感興趣請多提寶貴意見，大家互相學習，共同進步！

參考：

http://www.cnblogs.com/savorboard/p/dotnetcore-npoi.html

http://www.cnblogs.com/knowledgesea/archive/2012/11/16/2772547.html

http://www.cnblogs.com/luxiaoxun/p/3374992.html

https://github.com/tonyqus/npoi

NPOI操作Excel