親フォームを更新して、サブフォームを閉じます.

String msg=(String)request.getAttribute("Msg");
   if(msg!=null){
   	out.println("<script lanaguage=javascript>");
	out.println("alert('"+msg+"')");
	out.println("opener.location.assign(opener.location.href);");
	out.println("window.close();");
	out.println("</script>");
   }

opener.location.assign(opener.location.href);