NPOIHelper.cs (NPOI 2.1.1)

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Data;
 using System.IO;
 using NPOI.XSSF.UserModel;
 using NPOI.SS.UserModel;

 namespace NetLib
 {
     public static class NPOIHelper
     {
         public static void ExportToFile(DataSet dataSet, string fileFullPath)
         {
             List<DataTable> dts = new List<DataTable>();
             foreach (DataTable dt in dataSet.Tables) dts.Add(dt);
             ExportToFile(dts, fileFullPath);
         }
         public static void ExportToFile(DataTable dataTable, string fileFullPath)
         {
             List<DataTable> dts = new List<DataTable>();
             dts.Add(dataTable);
             ExportToFile(dts, fileFullPath);
         }
         public static void ExportToFile(IEnumerable<DataTable> dataTables, string fileFullPath)
         {
             IWorkbook workbook = new XSSFWorkbook();
             int i = ;
             foreach(DataTable dt in dataTables)
             {
                 string sheetName = string.IsNullOrEmpty(dt.TableName)
                     ? "Sheet " + (++i).ToString()
                     : dt.TableName;
                 ISheet sheet = workbook.CreateSheet(sheetName);

                 IRow headerRow = sheet.CreateRow();
                 for (int j = ; j < dt.Columns.Count; j++)
                 {
                     string columnName = string.IsNullOrEmpty(dt.Columns[j].ColumnName)
                         ? "Column " + j.ToString()
                         : dt.Columns[j].ColumnName;
                     headerRow.CreateCell(j).SetCellValue(columnName);
                 }

                 for (int a = ; a < dt.Rows.Count; a++)
                 {
                     DataRow dr = dt.Rows[a];
                     IRow row = sheet.CreateRow(a + );
                     for (int b = ; b < dt.Columns.Count; b++)
                     {
                         row.CreateCell(b).SetCellValue(dr[b] != DBNull.Value ? dr[b].ToString() : string.Empty);
                     }
                 }
             }

             using (FileStream fs = File.Create(fileFullPath))
             {
                 workbook.Write(fs);
             }
         }

         public static List<DataTable> GetDataTablesFrom(string xlsxFile)
         {
             if (!File.Exists(xlsxFile))
                 throw new FileNotFoundException("文件不存在");

             List<DataTable> result = new List<DataTable>();
             Stream stream = new MemoryStream(File.ReadAllBytes(xlsxFile));
             IWorkbook workbook = new XSSFWorkbook(stream);
             for (int i = ; i < workbook.NumberOfSheets; i++)
             {
                 DataTable dt = new DataTable();
                 ISheet sheet = workbook.GetSheetAt(i);
                 IRow headerRow = sheet.GetRow();

                 int cellCount = headerRow.LastCellNum;
                 for (int j = headerRow.FirstCellNum; j < cellCount; j++)
                 {
                     DataColumn column = new DataColumn(headerRow.GetCell(j).StringCellValue);
                     dt.Columns.Add(column);
                 }

                 int rowCount = sheet.LastRowNum;
                 for (int a = (sheet.FirstRowNum + ); a < rowCount; a++)
                 {
                     IRow row = sheet.GetRow(a);
                     if (row == null) continue;

                     DataRow dr = dt.NewRow();
                     for (int b = row.FirstCellNum; b < cellCount; b++)
                     {
                         if (row.GetCell(b) == null) continue;
                         dr[b] = row.GetCell(b).ToString();
                     }

                     dt.Rows.Add(dr);
                 }
                 result.Add(dt);
             }
             stream.Close();

             return result;
         }
     }
 }

NPOI 项目： http://npoi.codeplex.com/

本地下载：http://files.cnblogs.com/bruceleeliya/NPOI2.1.1.zip