public ActionForward index(ActionMapping mapping, ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception {
}
mapping:用于action处理完调用业务层逻辑后页面的跳转，常用mapping.findForward("path");
form:绑定在此action上面的用于接收页面传递参数和向页面传递数据的实体(struts2.x 中的modernDriven模式是对其的一种兼容);