Struts获取HttpServletRequest / HttpSession / ServletContext / HttpServletResponse对象

通过ServletActionContext.类直接获取：
public String rsa() throws Exception{
HttpServletRequest request = ServletActionContext.getRequest();
ServletContext servletContext = ServletActionContext.getServletContext();
HttpSession session = request.getSession() ;
HttpServletResponse response = ServletActionContext.getResponse();
return "scope";
}