C# NPOI读写XLSX文件

//NPOI读取XLSX格式读取流，需要重新创建流写入

//nuget：  NPOI 2.4.1
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System;
using System.Data;
using System.IO;

namespace ExcelExport
{
    class Program
    {
        static void Main(string[] args)
        {
            string path = @"1.xlsx";
            DataTable dt = GetDataTable();
            DataTableToExcel(dt, path);
        }

        private static DataTable GetDataTable()
        {
           var dt = new DataTable("cart");
            DataColumn dc1 = new DataColumn("prizename", Type.GetType("System.String"));
            DataColumn dc2 = new DataColumn("point", Type.GetType("System.Int16"));
            DataColumn dc3 = new DataColumn("number", Type.GetType("System.Int16"));
            DataColumn dc4 = new DataColumn("totalpoint", Type.GetType("System.Int64"));
            DataColumn dc5 = new DataColumn("prizeid", Type.GetType("System.String"));
            DataColumn dc6 = new DataColumn("Timer", Type.GetType("System.DateTime"));
            dt.Columns.Add(dc1);
            dt.Columns.Add(dc2);
            dt.Columns.Add(dc3);
            dt.Columns.Add(dc4);
            dt.Columns.Add(dc5);
            dt.Columns.Add(dc6);
            //以上代码完成了DataTable的构架，但是里面是没有任何数据的
            //Random r = new Random();
            for (int i = 0; i < 10; i++)
            {
                //int a = r.Next(1, 100);
                DataRow dr = dt.NewRow();
                dr["prizename"] = "娃娃" + i;
                dr["point"] = 10;
                dr["number"] = i;
                dr["totalpoint"] = 10;
                dr["prizeid"] = "001";
                dr["Timer"] = DateTime.Now.AddDays(i);
                dt.Rows.Add(dr);
            }
            return dt;
        }

        public static bool DataTableToExcel(DataTable dt,string path)
        {
            bool result = false;
            IWorkbook workbook = null;
            FileStream fs = null;
            IRow row = null;
            ISheet sheet = null;
            ICell cell = null;

            try
            {
                if (dt != null && dt.Rows.Count > 0)
                {
                    using (fs = new FileStream(path, FileMode.Open, FileAccess.ReadWrite))
                    {
                        workbook = new XSSFWorkbook(fs);
                        sheet = workbook.GetSheetAt(0);//创建一个名称为Sheet0的表  
                        int rowCount = dt.Rows.Count;//行数  
                        int columnCount = dt.Columns.Count;//列数  
                        //设置每行每列的单元格,  
                        for (int i = 0; i < rowCount; i++)
                        {
                            row = sheet.CreateRow(i + 9);//从第多少行开始写
                            for (int j = 0; j < columnCount; j++)
                            {
                                cell = row.CreateCell(j);//excel第二行开始写入数据  
                                cell.SetCellValue(dt.Rows[i][j].ToString());
                            }
                        }
                        using(var file2 = new FileStream(@"..\2.xlsx", FileMode.Create,FileAccess.ReadWrite)){
                            workbook.Write(file2);
                            file2.Close();
                        }

                        workbook.Write(fs);
                        result = true;
                    }
                }
                return result;
            }
            catch (Exception ex)
            {
                if (fs != null)
                {
                    fs.Close();
                }
                return false;
            }
        }
    }
}