asp.net code to download file in c#

if (e.CommandName == "Download")
{
string strFileName = e.CommandArgument.ToString();
string str = ConfigurationManager.AppSettings["AppPathRead"].ToString() + "/"+ strFileName;
FileInfo fileInfo = new FileInfo(str);
if (fileInfo.Exists)
{
Response.Clear();
Response.AddHeader("Content-Disposition", "attachment; filename=" + fileInfo.Name);
Response.AddHeader("Content-Length", fileInfo.Length.ToString());
Response.ContentType = "application/octet-stream";
Response.Flush();
Response.WriteFile(fileInfo.FullName);

}