问弹簧引导:视图无法到达控制器并具有"400 BAD_REQUEST“

EN

                    <td th:text="${Inj.sleepTest}"></td>
                    <td th:text="${Inj.sleepDose}"></td>
                    <td th:text="${Inj.nightTest}"></td>
                    <td th:text="${Inj.comment}"></td>
                    <td>
                        <form th:action="@{/delInj}" method="post">
                            <input type="hidden" id="id_injection" name="id_injection" value="${Inj.id_injection}">
                            <input class="btn btn-danger" type="submit" value="Submit">
                        </form>
                    </td>

@RequestMapping(value="/delInj", method= RequestMethod.POST)
    public ModelAndView delinject(Injection inj){
        ModelAndView mv = new ModelAndView();
        mv.setViewName("userOnly/MyInjections");
        int i = inj.getId_injection();
        System.out.println(i);

        return mv;

    }