什么是NPOI ?
简而言之，NPOI就是可以在没有Office的情况下对Word或Excel文档进行读写等操作。
使用方式 :
1、准备NPOI的dll文件
下载链接：https://npoi.codeplex.com/releases
2、将下载的dll文件引入项目中
3、引用命名空间
须知：
1、Excel表格分为：WorkBook（工作薄）-> Sheet（工作表） -> 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
代码如下：
1 /// <summary> 2 /// 将DataTable导入到Excel 3 /// </summary> 4 /// <param name="data">要导入的数据</param> 5 /// <param name="filepath">导入的文件路径（包含文件名称）</param> 6 /// <param name="sheename">要导入的表名</param> 7 /// <param name="iscolumwrite">是否写入列名</param> 8 /// <returns>导入Excel的行数</returns> 9 public int DataTableToExcel(DataTable data, string filepath, string sheename, bool iscolumwrite) 10 { 11 int i = 0; 12 int j = 0; 13 int count = 0; 14 ISheet sheet = null; 15 using (fs = new FileStream(filepath, FileMode.OpenOrCreate, FileAccess.ReadWrite)) 16 { 17 //根据Excel不同版本实例不同工作铺 18 if (filepath.IndexOf(".xlsx") > 0) // 2007版本 19 { 20 workbook = new XSSFWorkbook(); 21 } 22 else if (filepath.IndexOf(".xls") > 0) // 2003版本 23 workbook = new HSSFWorkbook(); 24 25 try 26 { 27 if (workbook != null) 28 { 29 sheet = workbook.CreateSheet(sheename); 30 } 31 else 32 { 33 return -1; 34 } 35 36 if (iscolumwrite == true) //写入DataTable的列名 37 { 38 IRow row = sheet.CreateRow(0); 39 for (j = 0; j < data.Columns.Count; ++j) 40 { 41 row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName); 42 } 43 count = 1; 44 } 45 else 46 { 47 count = 0; 48 } 49 50 for (i = 0; i < data.Rows.Count; ++i) 51 { 52 IRow row = sheet.CreateRow(count); 53 for (j = 0; j < data.Columns.Count; ++j) 54 { 55 row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString()); 56 } 57 count++; 58 } 59 workbook.Write(fs); //写入到excel 60 return count; 61 } 62 catch (Exception ex) 63 { 64 Console.WriteLine("Exception: " + ex.Message); 65 return -1; 66 } 67 finally { fs.Close(); fs.Dispose(); } 68 } 69 } 1 /// <summary> 2 /// 将Excel导入DataTable 3 /// </summary> 4 /// <param name="filepath">导入的文件路径（包括文件名）</param> 5 /// <param name="sheetname">工作表名称</param> 6 /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param> 7 /// <returns>DataTable</returns> 8 public DataTable ExcelToDataTable(string filepath, string sheetname, bool isFirstRowColumn) 9 { 10 ISheet sheet = null;//工作表 11 DataTable data = new DataTable(); 12 13 var startrow = 0; 14 using (fs = new FileStream(filepath, FileMode.Open, FileAccess.Read)) 15 { 16 try 17 { 18 if (filepath.IndexOf(".xlsx") > 0) // 2007版本 19 workbook = new XSSFWorkbook(fs); 20 else if (filepath.IndexOf(".xls") > 0) // 2003版本 21 workbook = new HSSFWorkbook(fs); 22 if (sheetname != null) 23 { 24 sheet = workbook.GetSheet(sheetname); 25 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 26 { 27 sheet = workbook.GetSheetAt(0); 28 } 29 } 30 else 31 { 32 sheet = workbook.GetSheetAt(0); 33 } 34 if (sheet != null) 35 { 36 IRow firstrow = sheet.GetRow(0); 37 int cellCount = firstrow.LastCellNum; //行最后一个cell的编号 即总的列数 38 if (isFirstRowColumn) 39 { 40 for (int i = firstrow.FirstCellNum; i < cellCount; i++) 41 { 42 ICell cell = firstrow.GetCell(i); 43 if (cell != null) 44 { 45 string cellvalue = cell.StringCellValue; 46 if (cellvalue != null) 47 { 48 DataColumn column = new DataColumn(cellvalue); 49 data.Columns.Add(column); 50 } 51 } 52 } 53 startrow = sheet.FirstRowNum + 1; 54 } 55 else 56 { 57 startrow = sheet.FirstRowNum; 58 } 59 //读数据行 60 int rowcount = sheet.LastRowNum; 61 for (int i = startrow; i < rowcount; i++) 62 { 63 IRow row = sheet.GetRow(i); 64 if (row == null) 65 { 66 continue; //没有数据的行默认是null 67 } 68 DataRow datarow = data.NewRow();//具有相同架构的行 69 for (int j = row.FirstCellNum; j < cellCount; j++) 70 { 71 if (row.GetCell(j) != null) 72 { 73 datarow[j] = row.GetCell(j).ToString(); 74 } 75 } 76 data.Rows.Add(datarow); 77 } 78 } 79 return data; 80 } 81 catch (Exception ex) 82 { 83 Console.WriteLine("Exception: " + ex.Message); 84 return null; 85 } 86 finally { fs.Close(); fs.Dispose(); } 87 } 88 } 测试代码：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Data; 6 7 using NPOIHelperTool; 8 using Bll; 9 namespace ConsoleApplication1 10 { 11 class Program 12 { 13 static void Main(string[] args) 14 { 15 DataTable data = new DataTable(); 16 for (int i = 0; i < 5; ++i) 17 { 18 data.Columns.Add("Columns_" + i.ToString(), typeof(string)); 19 } 20 21 for (int i = 0; i < 10; ++i) 22 { 23 DataRow row = data.NewRow(); 24 row["Columns_0"] = "item0_" + i.ToString(); 25 row["Columns_1"] = "item1_" + i.ToString(); 26 row["Columns_2"] = "item2_" + i.ToString(); 27 row["Columns_3"] = "item3_" + i.ToString(); 28 row["Columns_4"] = "item4_" + i.ToString(); 29 data.Rows.Add(row); 30 } 31 32 ExcelHelper h = new ExcelHelper(); 33 DataTable de = h.ExcelToDataTable(@"E:\Myuser.xls", "Sheet1", true); 34 int c = h.DataTableToExcel(data, @"E:\Test.xls", "sheet1", true); 35 IList<student> a = TypeUtil.ToList<student>(de); 36 } 37 38 } 39 class student 40 { 41 public string Id { get; set; } 42 public string Name { get; set; } 43 public string nc { get; set; } 44 } 45 } 参考：
https://www.cnblogs.com/Raning/p/5872822.html
https://blog.csdn.net/dcrmg/article/details/52356236
http://www.cnblogs.com/Erik_Xu/archive/2012/06/08/2541957.html
作者：遥远的Ta