how to view a document on browser?

protected void ShowFile(string URL)
       {
           if (URL != null && URL.ToString().Trim() != "")
           {
              
               FileInfo fileInfo = new FileInfo(URL);
               if (fileInfo.Exists)
               {
                   Response.Clear();
                   Response.AddHeader("Content-Disposition", "attachment; filename=" + FileName);
                   Response.AddHeader("Content-Length", fileInfo.Length.ToString());
                   Response.ContentType = "application/octet-stream";
                   Response.Flush();
                   Response.WriteFile(fileInfo.FullName);
                   Response.End();
               }
           }
}