/// 获取虚拟目录名称
        String contextPath=req.getContextPath();
        System.out.println(contextPath);
        //获取Servlet映射路径 getServletPath()
        String servletPath =req.getServletPath();
        System.out.println(servletPath);
        /// 获取访问者IP getRemoteAddr()
        String ip = req.getRemoteAddr();
        System.out.println(ip);
        // 获取请求消息的数据 getQueryString
        String queryString = req.getQueryString();
        System.out.println(queryString);

        /// 获取统一资源标识符
        String requestURI=req.getRequestURI();
        System.out.println(requestURI);

        //获取统一资源定位符
        StringBuffer requestURL=req.getRequestURL();
        System.out.println(requestURL);
        /*

            /ServletDemo07
            0:0:0:0:0:0:0:1
            null
            /ServletDemo07
            http://localhost:8080/ServletDemo07
         */