export to excel in asp.net from multipal datatable and multipal sheet

protected void btnexportexcel_Click(object
sender, EventArgs e)

{

DataTable TableName1= new DataTable();

DataTable TableName2= new DataTable();

DataSet ds = new DataSet();

ds.Merge(TableName1);

ds.Merge(TableName2);

ds.Tables[0].TableName = "TableName1";

ds.Tables[1].TableName = "TableName2";

ToExcel(ds, "" + filename + ".xls",
Page.Response);

}

private static string
getWorkbookTemplate()

{

var sb = new StringBuilder(818);

sb.AppendFormat(@"{0}", Environment.NewLine);

sb.AppendFormat(@"{0}", Environment.NewLine);

sb.AppendFormat(@",
Environment.NewLine);

sb.AppendFormat(@" xmlns:o=""urn:schemas-microsoft-com:office:office""{0}",
Environment.NewLine);

sb.AppendFormat(@"
xmlns:x=""urn:schemas-microsoft-com:office:excel""{0}",
Environment.NewLine);

sb.AppendFormat(@"
xmlns:ss=""urn:schemas-microsoft-com:office:spreadsheet""{0}",
Environment.NewLine);

sb.AppendFormat(@"
xmlns:html=""http://www.w3.org/TR/REC-html40"">{0}",
Environment.NewLine);

sb.AppendFormat(@" {0}", Environment.NewLine);

sb.AppendFormat(@"  {0}", Environment.NewLine);

sb.AppendFormat(@"  {0}", Environment.NewLine);

sb.AppendFormat(@"  {0}", Environment.NewLine);

sb.AppendFormat(@" {0}", Environment.NewLine);

sb.Append(@"{0}\r\n");

return
sb.ToString();

}

private static string
replaceXmlChar(string input)

{

input = input.Replace("&", "&amp");

input = input.Replace("<", "<");

input = input.Replace(">", ">");

input = input.Replace("\"", """);

input = input.Replace("'", "'");

return input;

}

private static string
getCell(Type type, object
cellData)

{

var data =
(cellData is DBNull)
? "" : cellData;

if
(type.Name.Contains("Int") ||
type.Name.Contains("Double") ||
type.Name.Contains("Decimal")) return string.Format("{0}", data);

if
(type.Name.Contains("Date")
&& data.ToString() != string.Empty)

{

return string.Format("{0}", Convert.ToDateTime(data).ToString("yyyy-MM-dd"));

}

return string.Format("{0}",
replaceXmlChar(data.ToString()));

}

private static string
getWorksheets(DataSet source)

{

var sw = new StringWriter();

if (source ==
null || source.Tables.Count == 0)

{

sw.Write("\r\n

\r\n\r\n
\r\n");

return
sw.ToString();

}

foreach (DataTable dt in
source.Tables)

{

if
(dt.Rows.Count == 0)

sw.Write(" +
replaceXmlChar(dt.TableName) + "\">\r\n

\r\n  ss:StyleID=\"s62\">\r\n
\r\n");

else

{

//write each row
data

var sheetCount
= 0;

for (int i = 0; i < dt.Rows.Count; i++)

{

if ((i %
rowLimit) == 0)

{

//add close tags
for previous sheet of the same data table

if ((i /
rowLimit) > sheetCount)

{

sw.Write("\r\n\r\n");

sheetCount = (i / rowLimit);

}

sw.Write("\r\n +
replaceXmlChar(dt.TableName) +

(((i / rowLimit) == 0) ? "" : Convert.ToString(i
/ rowLimit)) + "\">\r\n

");

//write column
name row

sw.Write("\r\n");

foreach (DataColumn dc in
dt.Columns)

sw.Write(string.Format("{0}",
replaceXmlChar(dc.ColumnName)));

sw.Write("");

}

sw.Write("\r\n");

foreach (DataColumn dc in
dt.Columns)

sw.Write(getCell(dc.DataType,
dt.Rows[i][dc.ColumnName]));

sw.Write("");

}

sw.Write("\r\n

\r\n");

}

}

return
sw.ToString();

}

public static string
GetExcelXml(DataTable dtInput, string filename)

{

var
excelTemplate = getWorkbookTemplate();

var ds = new DataSet();

ds.Tables.Add(dtInput.Copy());

var worksheets
= getWorksheets(ds);

var excelXml =
string.Format(excelTemplate, worksheets);

return excelXml;

}

public static string
GetExcelXml(DataSet dsInput, string filename)

{

var
excelTemplate = getWorkbookTemplate();

var worksheets
= getWorksheets(dsInput);

var excelXml =
string.Format(excelTemplate, worksheets);

return excelXml;

}

public static void ToExcel(DataSet dsInput, string
filename, HttpResponse response)

{

var excelXml =
GetExcelXml(dsInput, filename);

response.Clear();

response.Buffer = true;

response.BufferOutput = true;

//
response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");

response.Charset = "UTF-8";

response.ContentEncoding =
System.Text.Encoding.UTF8;

//response.ContentType
= "application/vnd.ms-excel";

response.AppendHeader("Content-Type", "application/ms-excel");

response.AppendHeader("Content-disposition", "attachment; filename=" + filename);

response.Write(excelXml);

response.Flush();

response.End();

}

public static void ToExcel(DataTable dtInput, string
filename, HttpResponse response)

{

var ds = new DataSet();

ds.Tables.Add(dtInput.Copy());

ToExcel(ds, filename,
response);

}