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 = ;
int j = ;
int count = ;
ISheet sheet = null; fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
if (fileName.IndexOf(".xlsx") > ) // 2007版本
workbook = new XSSFWorkbook();
else if (fileName.IndexOf(".xls") > ) // 2003版本
workbook = new HSSFWorkbook(); try
{
if (workbook != null)
{
sheet = workbook.CreateSheet(sheetName);
}
else
{
return -;
} if (isColumnWritten == true) //写入DataTable的列名
{
IRow row = sheet.CreateRow();
for (j = ; j < data.Columns.Count; ++j)
{
row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
}
count = ;
}
else
{
count = ;
} for (i = ; i < data.Rows.Count; ++i)
{
IRow row = sheet.CreateRow(count);
for (j = ; 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 -;
}
} /// <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 = ;
try
{
fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
if (fileName.IndexOf(".xlsx") > ) // 2007版本
workbook = new XSSFWorkbook(fs);
else if (fileName.IndexOf(".xls") > ) // 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();
}
}
else
{
sheet = workbook.GetSheetAt();
}
if (sheet != null)
{
IRow firstRow = sheet.GetRow();
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 + ;
}
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;
}
}
}
}
补充个方法
/// <summary>
/// 获取单元格的值（读取异常的时候调用）
/// </summary>
/// <param name="Cell"></param>
/// <returns></returns>
private object GetCellValue(ICell Cell)
{
object value = null;
try
{
switch (Cell.CellType)
{
case CellType.Blank:
value = Cell.StringCellValue;
break;
case CellType.String:
value = Cell.StringCellValue;
break;
case CellType.Numeric:
value = Cell.NumericCellValue.ToString();
break;
case CellType.Boolean:
value = Cell.BooleanCellValue;
break;
case CellType.Formula:
value = Cell.RichStringCellValue;
break;
case CellType.Error:
value = Cell.ErrorCellValue;
break;
case CellType.Unknown:
value = Cell.ToString();
break; }
}
catch (Exception)
{
value = System.DBNull.Value;
}
return value;
}
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 = ; i < ; ++i)
{
data.Columns.Add("Columns_" + i.ToString(), typeof(string));
} for (int i = ; i < ; ++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 = ; i < data.Rows.Count; ++i)
{
for (int j = ; 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 > )
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);
}
}
}
补充调用方法：
HttpPostedFileBase excelFile = Request.Files["fileName"]; //取到上传域
if (null != excelFile)
{
string fileName = Path.GetFileName(excelFile.FileName); //取到文件的名称 excelFile.SaveAs(Server.MapPath("~/Upload/") + System.IO.Path.GetFileName(excelFile.FileName));
string a = Server.MapPath("~/Upload/" + fileName);
ExcelHelper eh = new ExcelHelper(a); if (fileName.Equals("") || null == fileName)
{ //没有选择文件就上传的话，则跳回到上传页面
return false;
}
ExcelHelper eh = new ExcelHelper(a);
参考：http://www.cnblogs.com/luxiaoxun/p/3374992.html
