public interface IReader
    {
        DataTable Read(String path);
    }

    //使用NPOI读取Excel
    public class NPOIExcelReader : IReader
    {
        public DataTable Read(String path)
        {
            var dt = new DataTable();

            using (var fs = File.OpenRead(path))
            {
                var xss = new XSSFWorkbook(fs);
                var sheet = xss.GetSheetAt(0);

                var temp = xss.NumberOfSheets;

                var header = sheet.GetRow(0);
                foreach (var col in header)
                {
                    dt.Columns.Add(col.StringCellValue);
                }

                for (var i = 1; i < sheet.LastRowNum; i++)
                {
                    var row = sheet.GetRow(i);

                    var dr = dt.NewRow();

                    dr[0] = row.GetCell(0).StringCellValue;
                    dr[1] = row.GetCell(1).StringCellValue;
                    dr[2] = row.GetCell(2).DateCellValue;
                    dr[3] = row.GetCell(3).NumericCellValue;

                    dt.Rows.Add(dr);
                }
            }

            return dt;
        }
    }

    //使用OLEDB读取Excel
    public class OleDbExcelReader : IReader
    {
        public DataTable Read(String path)
        {
            var strConn = $"Provider=Microsoft.ACE.OLEDB.12.0;Extended Properties=Excel 12.0 XML;Data Source={path};";
            using (var conn = new OleDbConnection(strConn))
            {
                conn.Open();

                var sheets = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                var adapter = new OleDbDataAdapter($"SELECT * FROM [{sheets.Rows[0]["TABLE_NAME"]}]", strConn);
                var dt = new DataTable();
                adapter.Fill(dt);

                return dt;
            }
        }
    }

    //使用OLEDB读取CSV
    public class CSVReader : IReader
    {
        public DataTable Read(String path)
        {
            var fullPath = Path.GetFullPath(path);
            var strConn = $@"Provider=Microsoft.Jet.OleDb.4.0;Extended Properties='Text;HDR=YES;FMT=Delimited';Data Source={Path.GetDirectoryName(fullPath)};";
            using (var conn = new OleDbConnection(strConn))
            {
                conn.Open();

                var adapter = new OleDbDataAdapter($"SELECT * FROM [{ Path.GetFileName(path) }]", strConn);
                var dt = new DataTable();
                adapter.Fill(dt);
                return dt;
            }
        }
    }

    //纯文本读取CSV
    public class TextReader : IReader
    {
        public DataTable Read(String path)
        {
            var dt = new DataTable();
            using (var reader = new StreamReader(path, Encoding.Default))
            {
                var header = reader.ReadLine().Split(',');
                foreach (var item in header)
                {
                    dt.Columns.Add(item);
                }

                String line = null;
                while ((line = reader.ReadLine()) != null)
                {
                    var array = line.Split(',');

                    var row = dt.NewRow();
                    for (var i = 0; i < array.Length; i++)
                        row[i] = array[i];

                    dt.Rows.Add(row);
                }
            }
            return dt;
        }
    }