Xuất DataTable, DataView, Dataset[0] ra Excel nhanh chóng không cần add com...

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;

namespace DynamicForm
{
    public class ExportTableToExcel
    {
        public static void exportToExcel(DataTable sourceTable, string fileName)
        {
            exportToExcel(sourceTable, fileName, 0);
        }
        public static void exportToExcel(DataSet sourceDataset, string fileName)
        {
            exportToExcel(sourceDataset.Tables[0], fileName);
        }
        public static void exportToExcel(DataView sourceDataView, string fileName)
        {
            exportToExcel(sourceDataView.ToTable(), fileName);
        }
        public static void exportToExcel(DataSet sourceDataset, string fileName, int NOPs)
        {
            exportToExcel(sourceDataset.Tables[0], fileName, NOPs);
        }
        public static void exportToExcel(DataView sourceDataView, string fileName,int NOPs)
        {
            exportToExcel(sourceDataView.ToTable(), fileName, NOPs);
        }
      
        private static string decimalFormatPlace(int NOPs)//num of places
        {
            //if (NOPs < 0)
            //{
            //    throw new Exception("Parameter is not valid!");
            //}
            if (NOPs == 0)
                return "0";

            string strReturn = "0.";
                      
            if (NOPs >= 0)
            {
                for (int i = 0; i < NOPs; i++)
                {
                    strReturn += "0";
                }
            }
            return strReturn;
        }
        public static void exportToExcel(DataTable sourceTable, string fileName, int NOPs)
        {
            if (sourceTable.Rows.Count <= 0)
                throw new Exception("No data!");
            System.IO.StreamWriter excelDoc;

            excelDoc = new System.IO.StreamWriter(fileName);
            string startExcelXML = "\r\n<workbook "="" +                  "xmlns=\"urn:schemas-microsoft-com:office:spreadsheet\"\r\n" +
                  " xmlns:o=\"urn:schemas-microsoft-com:office:office\"\r\n " +
                  "xmlns:x=\"urn:schemas-    microsoft-com:office:" +
                  "excel\"\r\n xmlns:ss=\"urn:schemas-microsoft-com:" +
                  "office:spreadsheet\">\r\n \r\n " +
                  "\r\n " +
                  "\r\n " +
                  "\r\n <numberformat" +                  " ss:Format=\"@\"/>\r\n \r\n <style "="" +                   "ss:ID=\"Decimal\">\r\n \r\n </style>\r\n " +                   "\r\n " +                   "\r\n ";
            const string endExcelXML = "";

            int rowCount = 0;
            int sheetCount = 1;
         
            excelDoc.Write(startExcelXML);
            excelDoc.Write("");
            excelDoc.Write("");
            excelDoc.Write("");
            for (int x = 0; x < sourceTable.Columns.Count; x++)
            {
                excelDoc.Write("");
                excelDoc.Write(sourceTable.Columns[x].ColumnName);
                excelDoc.Write("");
            }
            excelDoc.Write("");
            foreach (DataRow x in sourceTable.Rows)
            {
                rowCount++;
                //if the number of rows is > 64000 create a new page to continue output

                if (rowCount == 64000)
                {
                    rowCount = 0;
                    sheetCount++;
                    excelDoc.Write("
");
                    excelDoc.Write(" ");
                    excelDoc.Write("");
                    excelDoc.Write("");
                }
                excelDoc.Write(""); //ID=" + rowCount + "

                for (int y = 0; y < sourceTable.Columns.Count; y++)
                {
                    System.Type rowType;
                    rowType = x[y].GetType();
                    switch (rowType.ToString())
                    {
                        case "System.String":
                            string XMLstring = x[y].ToString();
                            XMLstring = XMLstring.Trim();
                            XMLstring = XMLstring.Replace("&", "&");
                            XMLstring = XMLstring.Replace(">", ">");
                            XMLstring = XMLstring.Replace("<", "<");
                            excelDoc.Write("" +
                                           "");
                            excelDoc.Write(XMLstring);
                            excelDoc.Write("");
                            break;
                        case "System.DateTime":
                            //Excel has a specific Date Format of YYYY-MM-DD followed by

                            //the letter 'T' then hh:mm:sss.lll Example 2005-01-31T24:01:21.000

                            //The Following Code puts the date stored in XMLDate

                            //to the format above

                            DateTime XMLDate = (DateTime)x[y];
                            string XMLDatetoString = ""; //Excel Converted Date

                            XMLDatetoString = XMLDate.Year.ToString() +
                                 "-" +
                                 (XMLDate.Month < 10 ? "0" +
                                 XMLDate.Month.ToString() : XMLDate.Month.ToString()) +
                                 "-" +
                                 (XMLDate.Day < 10 ? "0" +
                                 XMLDate.Day.ToString() : XMLDate.Day.ToString()) +
                                 "T" +
                                 (XMLDate.Hour < 10 ? "0" +
                                 XMLDate.Hour.ToString() : XMLDate.Hour.ToString()) +
                                 ":" +
                                 (XMLDate.Minute < 10 ? "0" +
                                 XMLDate.Minute.ToString() : XMLDate.Minute.ToString()) +
                                 ":" +
                                 (XMLDate.Second < 10 ? "0" +
                                 XMLDate.Second.ToString() : XMLDate.Second.ToString()) +
                                 ".000";
                            excelDoc.Write("" +
                                         "");
                            excelDoc.Write(XMLDatetoString);
                            excelDoc.Write("");
                            break;
                        case "System.Boolean":
                            excelDoc.Write("" +
                                        "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.Int16":
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            excelDoc.Write("" +
                                    "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.Decimal":
                        case "System.Double":
                            excelDoc.Write("" +
                                  "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.DBNull":
                            excelDoc.Write("" +
                                  "");
                            excelDoc.Write("");
                            excelDoc.Write("");
                            break;
                        default:
                            throw (new Exception(rowType.ToString() + " not handled."));
                    }
                }
                excelDoc.Write("");
            }
            excelDoc.Write("");
            excelDoc.Write(" ");
            excelDoc.Write(endExcelXML);
            excelDoc.Close();
        }
    }
}