Open an existing Excel file using C#.

using System;
using System.Text;
using System.IO;

protected void BtnOpen_Click(object sender, EventArgs e)
{
            try
            {
                string XlsPath = Server.MapPath(@"~/abc.xlsx");
                FileInfo fileDet = new System.IO.FileInfo(XlsPath);
                Response.Clear();
                Response.Charset = "UTF-8";
                Response.ContentEncoding = Encoding.UTF8;
                Response.AddHeader("Content-Disposition", "attachment; filename=" + Server.UrlEncode(fileDet.Name));
                Response.AddHeader("Content-Length", fileDet.Length.ToString());
                Response.ContentType = "application/ms-excel";
                Response.WriteFile(fileDet.FullName);
                Response.End();
            }
            catch (Exception ex)
            {
                throw ex;
            }
}