1. a标签访问request等，如果直接在url中拼接是不行的，不允许访问，如：

//控制器
    @GetMapping
    public String index(@RequestParam(value = "page", defaultValue = "1") Integer page,
                        @RequestParam(value = "limit", defaultValue = "10") Integer limit,
                        @RequestParam(value = "user_id", required = false) Integer userId,
                        Model model
    ) {
        PageInfo<Trade> list = service.findByPage(page, limit, userId);
        if (list.getList().size() == 0) {
            return "admin/404";
        }
        model.addAttribute("list", list);
        return path + "/index";
    }

<a th:href="${'/admin/trade?page='+page}">test</a>，这里page、limit、user_id是不允许访问的（在普通标签中可用，如：<div th:text="${page}">test</div>），会报错，只能通过下面这种方式来访问

                <div class="layui-box layui-laypage layui-laypage-default" id="layui-laypage-1">
                    <a th:href="@{'/admin/trade'(page=${list.getPrePage()},user_id=${#request.getParameter('user_id')})}"
                       class="layui-laypage-prev"
                       th:classappend="${list.isHasPreviousPage()?'':'layui-disabled'}">
                        <i class="layui-icon"></i>
                    </a>
                    <a th:href="@{'/admin/trade'(page=${page},user_id=${#request.getParameter('user_id')})}"
                       th:each="page : ${list.getNavigatepageNums()}"
                       th:classappend="${list.getPageNum()==page?'layui-laypage-curr':''}">
                        <em class="layui-laypage-em"></em><em th:text="${page}">1</em>
                    </a>
                    <a th:href="@{/admin/trade(page=${list.getNextPage()},user_id=${#request.getParameter('user_id')})}"
                       class="layui-laypage-next"
                       th:classappend="${list.isHasNextPage()?'':'layui-disabled'}">
                        <i class="layui-icon"></i>
                    </a>
                </div>