前端加弹窗

前端加一段js即可

<script th:inline="javascript">
  /*<![CDATA[*/
    var msg = /*[[${msg}]]*/null;
    if(msg!=null){
        alert(msg);
    }
  /*]]>*/
</script>

后端request方法

@RequestMapping("/pollution")
public String pollutionWeb(HttpServletRequest request) {
   
    request.setAttribute(Constants.MSG, "暂无数据");

    return "pollution";
}