在实际项目中有很多场景遇到需要操作EXCEL文件，而常用到的库就有NPOI；NPOI是开源的POI 项目的.NET版，POI是一个开源的Java读写Excel、WORD等微软OLE2组件文档的项目, 使用 NPOI 你就可以在没有安装 Office 或者相应环境的机器上对 WORD/EXCEL 文档进行读写。在处理Excel文件上，NPOI 可以同时兼容 xls 和 xlsx。

程序集构成

一、引用

在NuGet里搜索NPOI，选择下图的项目安装即可；

二、程序示例：

部分代码如下：

（1）导出EXCEL代码

 public void Export_Excel(string path)  {        string extension= Path.GetExtension(path).ToLower();     IWorkbook workbook;     if (extension==".xlsx")     {         workbook = new XSSFWorkbook();      }      else       {          workbook = new HSSFWorkbook();       }      ISheet sheet = workbook.CreateSheet("表1");      using(FileStream fs=new FileStream(path,FileMode.Create,FileAccess.ReadWrite))      {         IRow row_Head = sheet.CreateRow(0);         for (int i = 0; i < dataGridView1.Columns.Count; i++)          {             ICell cell = row_Head.CreateCell(i);             cell.SetCellValue(dataGridView1.Columns[i].HeaderText);         }         for (int i = 0; i < dataGridView1.Rows.Count; i++)          {             IRow row1 = sheet.CreateRow(i + 1);             for (int j = 0; j < dataGridView1.Columns.Count; j++)             {                ICell cell = row1.CreateCell(j);                if(dataGridView1.Rows[i].Cells[j].Value==null)                      cell.SetCellValue("");                else                      cell.SetCellValue(dataGridView1.Rows[i].Cells[j].Value.ToString());                    }                }      workbook.Write(fs);       workbook.Close();     }   }

（2）读取EXCEL文件代码

public void Import_Excel(string path)        {            DataTable dt = new DataTable();            using (FileStream fsRead = new FileStream(path, FileMode.Open, FileAccess.Read))            {                string extension = Path.GetExtension(path).ToLower();                IWorkbook workbook;                if (extension == ".xlsx")                {                    workbook = new XSSFWorkbook(fsRead);                }                else                {                    workbook = new HSSFWorkbook(fsRead);                }                ISheet sheet = workbook.GetSheetAt(0);                IRow currentRow = sheet.GetRow(0);                //最后一个方格的编号 即总的列数                int cellCount = currentRow.LastCellNum;                dataGridView1.DataSource = null;                for (int i = 0; i < cellCount; i++)                {                    //DataColumn dc = new DataColumn();                    dt.Columns.Add( currentRow.GetCell(i).ToString());//增加列                }                for (int j = 0; j <= sheet.LastRowNum - 1; j++)                {                                        dt.Rows.Add();//增加行                    IRow currentRow1 = sheet.GetRow(j + 1);                    if (currentRow1 != null)                    {                        for (int c = 0; c < currentRow1.LastCellNum; c++)                        {                            ICell cell = currentRow1.GetCell(c);                            if (cell == null || cell.CellType == CellType.Blank)                            {                                dt.Rows[j][c] = DBNull.Value;                            }                            else                            {                                //如果当前单元格不为空，则根据单元格的类型获取数据                                switch (cell.CellType)                                {                                    //只有当单元格的数据类型是数字类型的时候使用cell.NumericCellValue来获取值。其余类型都使用字符串来获取.日期类型数据插入单元格后也是CellType.NUMERIC                                    case CellType.Numeric:                                        //cell.NumericCellValue;                                        dt.Rows[j][c] = cell.NumericCellValue;                                        break;                                    default:                                        //cell.ToString();                                        dt.Rows[j][c] = cell.ToString();                                        break;                                }                            }                        }                    }                }                dataGridView1.DataSource = dt;                workbook.Close();            }        }

三、感谢您的阅读，完整代码已上传，关注点赞后发送私信“NPOI”即可获取。