超市订单管理系统，用户管理实现

  public void query(HttpServletRequest req, HttpServletResponse resp){

        //查询用户列表
        //从前端获取数据
        String queryUserName = req.getParameter("queryname");
        String temp = req.getParameter("queryUserRole");
        String pageIndex = req.getParameter("pageIndex");
        int queryUserRole = 0;

        //获取用户列表
        UserServiceImpl userService = new UserServiceImpl();

        //第一次走这个页面，一定是第一页，页面大小是固定的
        int pageSize = 5;//可以把这个写到配置文件中，方便后期修改
        int currentPageNo=1;


        if (queryUserName == null){
            queryUserName = "";
        }

        if (temp!=null&& !temp.equals("")){
            queryUserRole =Integer.parseInt(temp);//解析页面，转换成整数型
        }
        if(pageIndex!=null){
            try {
                currentPageNo = Integer.parseInt(pageIndex);
            } catch (Exception e) {
                try {
                    resp.sendRedirect("error.jsp");
                } catch (IOException ioException) {
                    ioException.printStackTrace();
                }
            }
        }

        //获取用户总数(分页：上一页，下一页情况)
        int totalCount = userService.getUserCount(queryUserName, queryUserRole);
        //总页数支持
        PageSupport pageSupport = new PageSupport();
        pageSupport.setCurrentPageNo(currentPageNo);
        pageSupport.setPageSize(pageSize);
        pageSupport.setTotalCount(totalCount);

        //通过分页支持的公共类，查出一共有几页
        int totalPageCount=pageSupport.getTotalPageCount();

        //控制尾页和首页
        if (currentPageNo<1){
            currentPageNo = 1;
        }else if (currentPageNo>totalPageCount){//当页面大于最后一页
            currentPageNo=totalCount;
        }

        //获取用户展示
        List<User> userList = userService.getUserList(queryUserName, queryUserRole, currentPageNo, pageSize);
        req.setAttribute("userList",userList);

        RoleServiceImpl roleService = new RoleServiceImpl();
        List<Role> roleList = roleService.getRoleList();
        req.setAttribute("roleList",roleList);

        req.setAttribute("totalCount",totalCount);
        req.setAttribute("currentPageNo",currentPageNo);
        req.setAttribute("totalPageCount",totalPageCount);
        req.setAttribute("queryUserName",queryUserName);
        req.setAttribute("queryUserRole",queryUserRole);

        //返回前端
        try {
            req.getRequestDispatcher("userlist.jsp").forward(req,resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }