Excel导入到DataTable ，DataTable导入到Excel

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;
using NPOI.SS.Util;
using NPOI.HSSF.Util;using System;
using System.Collections.Gene