Spring MVC验证状态400

Question

我刚刚开始学习Spring并坚持使用表单验证(有dao/service和所有默认设置)

我尝试进行验证任务,以防止在字段中插入超过3个符号

@Size (min = 1, max = 3)

之后我想将表单数据插入到DB并将其输出到我的主页上,当数据满足我的验证并且由1到3个符号组成时,一切正常,但是当这些条件不满足时我尝试插入4或者更多的符号,我收到了HTTP STATUS 400.没有DB插入,也没有视图输出.所以我理解有验证,但我不明白为什么它会告诉我HTTP STATUS 400

@Controller
public class BookController {

    @Autowired
    private BookService bookService;

    @RequestMapping(value = "addBook", method = RequestMethod.GET)
    public String addUser(Model model) {

        model.addAttribute("user", new ValidationField());
        model.addAttribute("book", new Book());

        return "addBook";
    }

    @RequestMapping(value = "addBook", method = RequestMethod.POST)
    public String addBook( @ModelAttribute("user") @Valid ValidationField validationField, Book book, BindingResult result) {
        /*this.user(book, result);*/

        if (result.hasErrors()) {
            return "addBook";
        }
        this.bookService.addBook(book);

        return "redirect:/";
    }
}

验证类

public class ValidationField {

    @Size(min = 1, max = 3)
    private String name;

    @Size(min = 1, max = 3)
    private String genre;
}

并查看addBook.jsp

<%@taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@taglib prefix="t" tagdir="/WEB-INF/tags" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<t:tamplate>
  <form:form method="post" action="addBook" commandName="book" modelAttribute="user">
      <form:errors path="*" cssClass="alert alert-danger" element="div" />
        <table>
            <tr>
                <td><form:input path="name"/></td>
                <td><form:errors path="name"/></td>
            </tr>
            <tr>
                <td><form:input path="genre" /></td>
                <td><form:errors path="genre"/></td>
            </tr>
            <tr>
                <td colspan="2"> <input type="submit" value="add book"> </td>
            </tr>
        </table>
    </form:form>
</t:tamplate>

Answer 1

您应该将BindingResult设置为立即遵循ModelAttribute,例如

public String addBook( @ModelAttribute("user") @Valid ValidationField validationField, BindingResult result, Book book)

请查看文档http://docs.spring.io/spring/docs/current/spring-framework-reference/html/mvc.html#mvc-ann-methods

除了BindingResult参数之外,大多数参数可以以任意顺序使用

并继续

Errors或BindingResult参数必须遵循立即绑定的模型对象,因为方法签名可能包含多个模型对象,而Spring将为每个模型对象创建单独的BindingResult实例