请求对象HttpServletRequest——获取各种路径的方法

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println(req.getContextPath());  // /my-web

        System.out.println(req.getServletPath());  // /myServlet

        System.out.println(req.getRemoteAddr());   // 127.0.0.1

        System.out.println(req.getQueryString());  // null

        System.out.println(req.getRequestURI());   // /my-web/myServlet

        System.out.println(req.getRequestURL());   // http://localhost:8080/my-web/myServlet
    }