DataTable to File - vb.net

Question

Sub DataTable2CSV(ByVal table As DataTable, ByVal filename As String)
DataTable2CSV(table, filename, vbTab)
End Sub
Sub DataTable2CSV(ByVal table As DataTable, ByVal filename As String, _
ByVal sepChar As String)
Dim writer As System.IO.StreamWriter
Try
writer = New System.IO.StreamWriter(filename)
' first write a line with the columns name
Dim sep As String = ""
Dim builder As New System.Text.StringBuilder
For Each col As DataColumn In table.Columns
builder.Append(sep).Append(col.ColumnName)
sep = sepChar
Next
writer.WriteLine(builder.ToString())
' then write all the rows
For Each row As DataRow In table.Rows
sep = ""
builder = New System.Text.StringBuilder
For Each col As DataColumn In table.Columns
builder.Append(sep).Append(row(col.ColumnName))
sep = sepChar
Next
writer.WriteLine(builder.ToString())
Next
Finally
If Not writer Is Nothing Then writer.Close()
End Try
End Sub
I found this piece of coding on the internet after searching for "DataTable to File VB.net". What I would like to do is output this in filestream, is it possible to set up a response outputstream? Thanks
EDIT: To Clarify (Change up) Here is what I am working with now:
Protected Sub DoExportFinancials()
Dim ef As New ExportFinancials()
ef.Behavior = ExportFinancials.ObjectBehavior.Export
If ef.Load() = True Then
Me.GridView4.DataSource = ef.DT
Me.GridView4.DataBind()
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
Response.AddHeader("content-disposition", "attachment;filename=FileName.xls")
' Response.Charset = ""
'Response.Cache.SetCacheability(HttpCacheability.NoCache)
Dim stringWrite As StringWriter = New StringWriter
Dim htmlWrite As HtmlTextWriter = New HtmlTextWriter(stringWrite)
GridView4.RenderControl(htmlWrite)
Response.Write(stringWrite.ToString())
Response.End()
End If

Answer 1

The below should work,
Dim FilePath As String = serverPath & "\App_Data\" & FileName
Response.Clear()
Response.ContentType = "text/csv"
Response.AddHeader("Content-Disposition", "attachment; filename=" & FileName)
Response.TransmitFile(FilePath)
Response.End()
EDIT: Based on more details of Question,
[Change] : How to pass DataTable to Response Stream as CSV/Excel file, without writing it to Disk on server.
One way of accomplishing the above is first to Bind DataTable to a GridView and then the contents of GridView can be passed to the response stream using the below,
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
Response.AddHeader("content-disposition", "attachment;filename=FileName.xls")
Response.Charset = "" Response.Cache.SetCacheability(HttpCacheability.NoCache)
Dim stringWrite As StringWriter = New StringWriter
Dim htmlWrite As HtmlTextWriter = New HtmlTextWriter(stringWrite)
grid.RenderControl(htmlWrite) Response.Write(stringWrite.ToString())
Response.End()