java - 继续获取: Neither BindingResult nor plain target object for bean name 'index' available as request attribute

Question

我不明白我做错了什么。我有一个 Controller :

@Controller
@RequestMapping(value = "/index.htm")
public class LoginController {

    @Autowired
    private AccountService accountService;

    @RequestMapping(method = RequestMethod.GET)
    public String showForm(Map model) {
        model.put("index", new LoginForm());
        return "index";
    }

    @ModelAttribute("index")
    public LoginForm getLoginForm() {
        return new LoginForm();
    }

    @RequestMapping(method = RequestMethod.POST)
    public String processForm(LoginForm loginForm, BindingResult result,
                              Map model) {

        if (result.hasErrors()) {
            HashMap<String, String> errors = new HashMap<String, String>();
            for (FieldError error : result.getFieldErrors()) {
                errors.put(error.getField(), error.getDefaultMessage());
            }
            model.put("errors", errors);
            return "index";
        }

        List<Account> accounts = accountService.findAll();
        loginForm = (LoginForm) model.get("loginForm");


        model.put("index", loginForm);
        return "loginsuccess";
    }

}

和 Spring html 表单:

<form:form action="index.htm" commandName="index">

    <table cellspacing="10">
        <tr>
            <td>
                <form:label path="username">
                    <spring:message code="main.login.username"/>
                </form:label>
            </td>
            <td>
                <form:input path="username" cssClass="textField"/>
            </td>
        </tr>
        <tr>
            <td>
                <form:label path="password">
                    <spring:message code="main.login.password"/>
                </form:label>
            </td>
            <td>
                <form:password path="password" cssClass="textField"/>
            </td>
        </tr>
        <tr>
            <td>
                <input type="submit" class="button" value="Login"/>
            </td>
        </tr>
    </table>

</form:form>

当我尝试访问 URL:http://localhost:8080/webclient/index.htm

我不断收到此异常:

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'index' available as request attribute

我的 Controller 出了什么问题，为什么我总是遇到这样的异常？

Answer 1

我将进行以下更改。首先，您的 GET 方法应该类似于:

@RequestMapping(method = RequestMethod.GET)
public String showForm(@ModelAttribute("index") LoginForm loginForm) {
    return "index";
}

使用@ModelAttribute注释会自动将“index”放入请求的模型中。

并且您的 POST 方法声明应该类似于:

@RequestMapping(method = RequestMethod.POST)
public String processForm(@ModelAttribute("index") LoginForm loginForm, 
                          BindingResult result, Map model) {

最后，可能是真正的问题，将 Controller 类的 @RequestMapping 注释更改为:

@RequestMapping(value = "/index")

您拥有的“.htm”是多余的。您已经配置了 web.xml 和 Spring 配置来响应“.htm”请求。