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;
}
/// <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;
}
}
}
}
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);
}
}
}
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：NPOI-Lib.rar
1.NPOI下载地址：http://npoi.codeplex.com/releases/view/38113
2.NPOI学习系列教程推荐：http://www.cnblogs.com/tonyqus/archive/2009/04/12/1434209.html
参考：
http://www.cnblogs.com/Erik_Xu/archive/2012/06/08/2541957.html
http://www.cnblogs.com/linzheng/archive/2010/12/20/1912137.html
http://www.cnblogs.com/knowledgesea/archive/2012/11/16/2772547.html
