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. 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,XSSF适用2007版本及其以上的。
下面是用NPOI读写Excel的例子：ExcelHelper封装的功能主要是把DataTable中数据写入到Excel中，或者是从Excel读取数据到一个DataTable中。
ExcelHelper类：
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; } /// /// 将DataTable数据导入到excel中 /// /// 要导入的数据 /// DataTable的列名是否要导入 /// 要导入的excel的sheet的名称 /// 导入数据行数(包含列名那一行) 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; } } /// /// 将excel中的数据导入到DataTable中 /// /// excel工作薄sheet的名称 /// 第一行是否是DataTable的列名 /// 返回的DataTable 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; } } }} 测试代码：
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data;namespace NPOIExcelExample{ class Program { static DataTable GenerateData() { DataTable data = new DataTable(); for (int i = 0; i < 5; ++i) { data.Columns.Add("Columns_" + i.ToString(), typeof(string)); } for (int i = 0; i < 10; ++i) { DataRow row = data.NewRow(); row["Columns_0"] = "item0_" + i.ToString(); row["Columns_1"] = "item1_" + i.ToString(); row["Columns_2"] = "item2_" + i.ToString(); row["Columns_3"] = "item3_" + i.ToString(); row["Columns_4"] = "item4_" + i.ToString(); data.Rows.Add(row); } return data; } static void PrintData(DataTable data) { if (data == null) return; for (int i = 0; i < data.Rows.Count; ++i) { for (int j = 0; j < data.Columns.Count; ++j) Console.Write("{0} ", data.Rows[i][j]); Console.Write("\n"); } } static void TestExcelWrite(string file) { try { using (ExcelHelper excelHelper = new ExcelHelper(file)) { DataTable data = GenerateData(); int count = excelHelper.DataTableToExcel(data, "MySheet", true); if (count > 0) Console.WriteLine("Number of imported data is {0} ", count); } } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); } } static void TestExcelRead(string file) { try { using (ExcelHelper excelHelper = new ExcelHelper(file)) { DataTable dt = excelHelper.ExcelToDataTable("MySheet", true); PrintData(dt); } } catch (Exception ex) { Console.WriteLine("Exception: " + ex.Message); } } static void Main(string[] args) { string file = "..\\..\\myTest.xlsx"; TestExcelWrite(file); TestExcelRead(file); } }} 签于这篇文章阅读量较高，更新一下我使用Aspose.Cells的另一个版本：
PS：Aspose是要收费的
using System;using System.Collections.Generic;using System.Data;using System.IO;using System.Linq;using System.Text;using Aspose.Cells;namespace NetUtilityLib{ public static class ExcelHelper { public static int DataTableToExcel(DataTable data, string fileName, string sheetName, bool isColumnNameWritten) { int num = -1; try { Workbook workBook; Worksheet worksheet = null; if (File.Exists(fileName)) workBook = new Workbook(fileName); else workBook = new Workbook(); if (sheetName == null) { if (workBook.Worksheets.Count > 0) { worksheet = workBook.Worksheets[0]; } else { sheetName = "Sheet1"; workBook.Worksheets.RemoveAt(sheetName); worksheet = workBook.Worksheets.Add(sheetName); } } if (worksheet != null) { worksheet.Cells.Clear(); num = worksheet.Cells.ImportDataTable(data, isColumnNameWritten, 0, 0, false); workBook.Save(fileName); } } catch (Exception ex) { Console.WriteLine(ex.Message); } return num; } public static void AddOneRowToExcel(DataRow dataRow, string fileName, string sheetName) { try { Workbook workBook; if (File.Exists(fileName)) workBook = new Workbook(fileName); else workBook = new Workbook(); Worksheet worksheet=null; if (sheetName == null) { worksheet = workBook.Worksheets[0]; } else { worksheet = workBook.Worksheets[sheetName]; } if (worksheet != null) { worksheet.Cells.ImportDataRow(dataRow, worksheet.Cells.MaxDataRow + 1,0); //worksheet.Cells.ImportArray(dataArray, worksheet.Cells.MaxDataRow+1, 0, false); workBook.Save(fileName); } } catch (Exception ex) { Console.WriteLine(ex.Message); } } public static DataTable ExcelToDataTable(string fileName, string sheetName, bool isFirstRowColumnName) { DataTable data = new DataTable(); try { Workbook workbook = null; FileInfo fileInfo = new FileInfo(fileName); if (fileInfo.Extension.ToLower().Equals(".xlsx")) workbook = new Workbook(fileName, new LoadOptions(LoadFormat.Xlsx)); else if (fileInfo.Extension.ToLower().Equals(".xls")) workbook = new Workbook(fileName, new LoadOptions(LoadFormat.Excel97To2003)); if (workbook != null) { Worksheet worksheet = null; if (sheetName != null) { worksheet = workbook.Worksheets[sheetName]; } else { worksheet = workbook.Worksheets[0]; } if (worksheet != null) { data = worksheet.Cells.ExportDataTable(0, 0, worksheet.Cells.MaxRow+1, worksheet.Cells.MaxColumn+1, isFirstRowColumnName); return data; } } else { return data; } } catch (Exception ex) { Console.WriteLine(ex.Message); } return data; } }}
Excel相关DLL下载：
1.NPOI下载地址：
2.NPOI学习系列教程推荐：
参考：