file download code in C#

 #region File download
    private void forceDownload(string filePath, bool forceDownload)
    {
        try
        {
            string path = MapPath(filePath);
            string name = Path.GetFileName(filePath);
            string extension = Path.GetExtension(filePath);
            string contentType = string.Empty;
            switch (extension.ToLower())
            {
                case ".jpg":
                    contentType = "image/JPEG";
                    break;
                case ".gif":
                    contentType = "image/GIF";
                    break;
                case ".html":
                case ".htm":
                    contentType = "image/HTML";
                    break;
                case ".pdf":
                    contentType = "Application/pdf";
                    break;
                case ".doc":
                case ".rtf":
                    //for Microsoft Word files
                    contentType = "Application/msword";
                    break;
                case ".xls":
                    //for Microsoft Excel files
                    contentType = "Application/x-msexcel";
                    break;
                case ".txt":
                    contentType = "text/plain";
                    break;
            }

            if (forceDownload)
            {
                Response.AppendHeader("content-disposition", "attachment; filename=" + name);
            }
            if (contentType != string.Empty)
                //Set the appropriate ContentType.
                Response.ContentType = contentType;
            //Write the file directly to the HTTP content output stream.
            Response.WriteFile(path);
            Response.End();
        }
        catch (Exception errmsg)
        {
            Response.Write(errmsg.Message.ToString());
        }
    }
    #endregion
    protected void LinkButtonDownLoad_Click(object sender, EventArgs e)
    {
        string filePath = ".\\uploadData\\" + LinkButtonDownLoad.Text.Trim();
        if (File.Exists(Server.MapPath(filePath)))
        {
            forceDownload(filePath, true);
        }
        else
        {
            ClientScript.RegisterStartupScript(this.GetType(), "onload", "alert('Sorry, file not found!');", true);
        }
    }
}