C# Excel使用NPOI

using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System.IO;
 private void ReadPatternExcel(string filePath,int sheetIndex)
        {
            IWorkbook workBook = null;
            ISheet sheet;
            try
            {
                FileInfo fileInfo = new FileInfo(filePath);
                if(fileInfo.Exists)
                {
                    FileStream fs = fileInfo.OpenRead();
                    switch (fileInfo.Extension)
                    {
                        //xls是03，用HSSFWorkbook打开，.xlsx是07或者10用XSSFWorkbook打开
                        case ".xls":
                            workBook = new HSSFWorkbook(fs);
                            break;
                        case ".xlsx":
                            workBook = new XSSFWorkbook(fs);
                            break;
                        default:
                            break;
                    }
                    fs.Close();//关闭文件流
                }

                if(workBook!=null)
                {
                    sheet = workBook.GetSheetAt(sheetIndex);
                    IRow headerRow = sheet.GetRow(0);
                    int colCount = headerRow.LastCellNum;//列数
                    //遍历
                    for(int i=sheet.FirstRowNum;i<=sheet.LastRowNum;i++)
                    {
                        Console.Write("row "+i.ToString()+" ");
                        NPOI.SS.UserModel.IRow row = sheet.GetRow(i);//得到一行
                        for(int j=row.FirstCellNum;j<row.LastCellNum;j++)
                        {
                            string data = row.GetCell(j).ToString();
                            Console.Write(data);
                        }
                        Console.WriteLine();
                    }
                }


            }
            catch(Exception e)
            {
                MessageBox.Show(e.Message.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                workBook = null;
                sheet = null;
            }

        }