博主的開發環境是 spring boot +mybatis + layui +thymeleaf

解決方案:
如果你的controller不打算返回模板的話就一定別忘了給它加上@Resopnsebody註解.
eg:

    @RequestMapping(value = "/sys_stuff/edit")
    public String edit(String id, Model model) {
        if (id == null) {
            Stuffs stuff = new Stuffs();
        }
        Stuffs stuff = qingYunService.findStuffById
 
(Integer.parseInt(id));
        System.out.println(stuff.toString());
        model.addAttribute("stuff", stuff);
        return "modifystuff";
    }

    //    @ResponseBody 要加上  
    @RequestMapping(value = "/sys_stuff/update")
    @ResponseBody
    public Result update(@RequestParam("name") String name ,
                       @RequestParam("id"
 
) String id,
                       @RequestParam("lid") String lid,
                       @RequestParam("mid") String mid) {
        Stuffs stuff = qingYunService.findStuffById(Integer.parseInt(id));
        stuff.setName(name);

        System.out.println("次型別id=====>>>"+lid+"主型別id=====>>>"
 
+mid);
        LittleTypes littleType = qingYunService.findLittleTypeById(Integer.parseInt(lid));

        System.out.println("初始littetype============>>>>>"+littleType.toString());
        littleType.setMainTypes(qingYunService.findMainTypeById(Integer.parseInt(mid)));

        stuff.setLittleTypes(littleType);
        qingYunService.modifyStuff(stuff);
        Result result = Result.success();
        return Result.success();
    }

報錯資訊:

"Error resolving template "sys_stuff/update", template might not exist or might not be accessible by any of the configured Template Resolvers"

番外:

這個報錯資訊最讓人矇蔽的不是我看不懂意思,而是我壓根就沒有寫sys_stuff/update這個模板,還有我從未打算渲染這個模板!!

所以,這就讓我摸不著頭腦了……….

曾經我以為我Ajax(阿加克斯)有問題!然後把js改來改去也不成功!各位看官可以看看我的ajax麼!

<script th:src="@{/lib/layui/layui.js}"></script>
<script type="text/javascript" th:inline="javascript">

    layui.config({
        base: '/js/layui-modules/'
    }).use(['form', 'layer', 'laypage', 'tools'], function () {
        var $ = layui.jquery,
            form = layui.form(),
            laypage = layui.laypage,
            tools = layui.tools;
        //監聽提交

        //監聽提交  data是什麼  傳送到後臺?????
        form.on('submit(btnSave)', function(data) {
            //roleId在這裡沒多少用
            $.ajax({
                type: 'POST',
                url: /*[[@{/sys_stuff/update}]]*/'',
                dataType:'json',
                data: data.field,
                async: true,
                success: function (result) {
                    console.log(result.code)
                    //媽的 沒加@Responsebody註解
                    if (result.code == 0) {
                        layer.msg('success:儲存成功', {icon: 1, time:1000});
                        setTimeout(function(){
                            top.layer.closeAll('iframe');
                            //重新整理父親的頁面
                            parent.refreshIframe();
                        },800);
                    } else {
                        consol.alert(result.code);
                        layer.msg('eles:儲存失敗！'+result.msg, {icon: 2, time:1000});
                    }
                },
                error: function (result, type) {
                    layer.msg('error:儲存失敗！', { icon: 2, time:1000 });
                }
            });
            console.log(data.field)
            return false;
        });

    });

</script>