BindingResult和普通目标对象都没有...异常

当您在logincontroller中显示showAllComments.jsp时，您需要添加一个表单bean类（即Comment）作为模型的属性。

@RequestMapping(value = "/log_in", method = RequestMethod.POST)public ModelAndView tryToLogin(@RequestParam("uName") String uName, @RequestParam("pW") String pW,      HttpServletResponse response, HttpServletRequest request) {    ModelAndView ret = new ModelAndView("login", "command", new User());    User user = userService.existingUser(uName, pW);    loggedInUser = new User();    model.addAttribute("command", new Comment());    if (user != null) {        Map<String, Object> model = new HashMap<String, Object>(); model.put("COMMENTS", allComments); model.put("LOGGED_IN_USER", loggedInUser);        ret = ModelAndView("showAllComments", model);    }    return ret;}

这应该工作正常。

更新

使用“命令”作为命令对象名称不是一个好习惯。对于班级注释，您可以使用“注释”或类似的内容。如果这样做，请使用以下代码更新表单。

<form:form method="post" action="postNewComment.html" commandName="comment">    <table>        <tr> <td><form:label path="comment">         COMMENT     </form:label></td> <td><form:input path="comment" /></td>        </tr>        <tr> <td colspan="2"><input type="submit"     value="WRITE" /></td>        </tr>    </table></form:form>

在所有其他地方进行相同的更改，即

model.addAttribute("comment", new Comment());

和

@ModelAttribute("comment")

更新2

    @RequestMapping(value="userRegistration", method = RequestMethod.GET)public ModelAndView showUserRegistrationForm(Model model){    model.addAttribute("user", new AccountDetailsForm());    return new ModelAndView("userRegistration");}