1、整个Excel表格叫做工作表：WorkBook（工作薄），包含的叫页（工作表）：Sheet；行：Row；单元格Cell。
2、NPOI是POI的C#版本，NPOI的行和列的index都是从0开始
3、POI读取Excel有两种格式一个是HSSF，另一个是XSSF。 HSSF和XSSF的区别如下：
HSSF is the POI Project's pure Java implementation of the Excel '97(-2007) file format. (.xls)
XSSF is the POI Project's pure Java implementation of the Excel 2007 OOXML (.xlsx) file format.
即：HSSF适用2007以前的版本（.xls）,XSSF适用2007版本及其以上的(.xlsx)。
using System; using System.Collections.Generic; using System.Linq; using System.Text; using NPOI.SS.UserModel; using NPOI.XSSF.UserModel; using NPOI.HSSF.UserModel; using System.IO; using System.Data; namespace NetUtilityLib { public class ExcelHelper : IDisposable { private string fileName = null; //文件名 private IWorkbook workbook = null; private FileStream fs = null; private bool disposed; public ExcelHelper(string fileName) { this.fileName = fileName; disposed = false; } /// <summary> /// 将DataTable数据导入到excel中 /// </summary> /// <param name="data">要导入的数据</param> /// <param name="isColumnWritten">DataTable的列名是否要导入</param> /// <param name="sheetName">要导入的excel的sheet的名称</param> /// <returns>导入数据行数(包含列名那一行)</returns> public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten) { int i = 0; int j = 0; int count = 0; ISheet sheet = null; fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite); if (fileName.IndexOf(".xlsx") > 0) // 2007版本 workbook = new XSSFWorkbook(); else if (fileName.IndexOf(".xls") > 0) // 2003版本 workbook = new HSSFWorkbook(); try { if (workbook != null) { sheet = workbook.CreateSheet(sheetName); } else { return -1; } if (isColumnWritten == true) //写入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); //写入到excel return count; } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); return -1; } } /// <summary> /// 将excel中的数据导入到DataTable中 /// </summary> /// <param name="sheetName">excel工作薄sheet的名称</param> /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param> /// <returns>返回的DataTable</returns> public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn) { ISheet sheet = null; DataTable data = new DataTable(); int startRow = 0; try { fs = new FileStream(fileName, FileMode.Open, FileAccess.Read); if (fileName.IndexOf(".xlsx") > 0) // 2007版本 workbook = new XSSFWorkbook(fs); else if (fileName.IndexOf(".xls") > 0) // 2003版本 workbook = new HSSFWorkbook(fs); if (sheetName != null) { sheet = workbook.GetSheet(sheetName); if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet { sheet = workbook.GetSheetAt(0); } } else { sheet = workbook.GetSheetAt(0); } if (sheet != null) { IRow firstRow = sheet.GetRow(0); int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数 if (isFirstRowColumn) { for (int i = firstRow.FirstCellNum; i < cellCount; ++i) { ICell cell = firstRow.GetCell(i); if (cell != null) { string cellValue = cell.StringCellValue; if (cellValue != null) { DataColumn column = new DataColumn(cellValue); data.Columns.Add(column); } } } startRow = sheet.FirstRowNum + 1; } else { startRow = sheet.FirstRowNum; } //最后一列的标号 int rowCount = sheet.LastRowNum; for (int i = startRow; i <= rowCount; ++i) { IRow row = sheet.GetRow(i); if (row == null) continue; //没有数据的行默认是null DataRow dataRow = data.NewRow(); for (int j = row.FirstCellNum; j < cellCount; ++j) { if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null dataRow[j] = row.GetCell(j).ToString(); } data.Rows.Add(dataRow); } } return data; } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); return null; } } public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!this.disposed) { if (disposing) { if (fs != null) fs.Close(); } fs = null; disposed = true; } } } }
操作实列:
string localFilePath = ""; DataTable dtExcel = new DataTable(); //点了保存按钮进入 if (openFileDialog1.ShowDialog() == DialogResult.OK)// openFileDialog1不要再问我这是什么！ { //获得文件路径 localFilePath = openFileDialog1.FileName.ToString(); string strMs = (localFilePath.Split('.')[1]).ToString(); if (strMs != "xlsx" && strMs != "xls") { MessageBox.Show("请导入正确的Excel文件"); return; } try { using (ExcelHelper excelHelper = new ExcelHelper(localFilePath)) { dtExcel = excelHelper.ExcelToDataTable("MySheet", true); dtAll = dtExcel; } } catch { MessageBox.Show("其它程序正在占用文件不能导入"); return; } if (dtExcel != null) { try { Double allDou = 0, ShuiDou = 0; DataTable datNew = dtExcel.DefaultView.ToTable(false, new string[] { "序号", "商品名称", "规格型号", "计量单位", "单价", "数量", "金额", "税率" }); datNew.Columns.Add("税额"); foreach (DataRow row in datNew.Rows) { row["金额"] = (Double.Parse(row["单价"].ToString()) * Double.Parse(row["数量"].ToString())).ToString(); row["税额"] = (Double.Parse(row["金额"].ToString()) * 0.17).ToString(); allDou = allDou + Double.Parse(row["金额"].ToString()); ShuiDou = ShuiDou + (Double.Parse(row["金额"].ToString()) * 0.17); if (radioYes.Checked) { row["单价"] = (Double.Parse(row["单价"].ToString()) / 1.17); } } txtAll.Text = (ShuiDou + allDou).ToString(); txtShui.Text = ShuiDou.ToString(); txtTotalAll.Text = allDou.ToString(); GvList.DataSource = datNew; } catch { MessageBox.Show("其它程序正在占用文件不能导入"); } } else { MessageBox.Show("其它程序正在占用文件不能导入"); } }