一个servlet处理多个功能

servlet中：

String servletPath = request.getServletPath();
        String methodName = servletPath.substring(1);
        methodName = methodName.substring(0, methodName.length() - 3);
        Method method;
        try {
            method = getClass().getDeclaredMethod(methodName,
                    HttpServletRequest.class, HttpServletResponse.class);
            method.invoke(this, request,response);
        } catch (NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }

    private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        System.out.println("update");
    }
    private void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<User> list = dao.getAll();
        request.setAttribute("list", list);
        request.getRequestDispatcher("/index.jsp").forward(request, response);;
        System.out.println("query");
    }
    private void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        System.out.println("delete");
    }private void add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        System.out.println("add");
    }

web.xml文件：

 <servlet-mapping>
    <servlet-name>UserServlet</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>

jsp：

<a href="add.do">add</a>
<a href="delete.do">delete</a>
<a href="query.do">query</a>
<a href="update.do">update</a>