java - 使用@Valid 会抛出异常并且在基本的 Spring 3.0 MVC 程序中不起作用

Question

我正在使用 Spring In Action 3rd Action 学习 Spring MVC ，我已经实现了显示用户注册表单的基本程序，一旦我们提交了表单，它将使用 @Valid 进行验证。 .

这是我的 Spring Controller :

@Controller
@RequestMapping("/spitter")
public class SpitterController {
        private final SpitterService spitterService;

        @Inject
        public SpitterController(SpitterService spitterService) {
            this.spitterService = spitterService;
        }

        @RequestMapping(method = RequestMethod.GET, params = "new")
        public String createSpitterProfile(Model model) {
            Spittle spittle = new Spittle();
            model.addAttribute(spittle);

            model.addAttribute(new Spitter());
            return "spittles/edit";
        }

            @RequestMapping(method = RequestMethod.POST)
            public String addSpitterFromForm(@Valid Spitter spitter,
            BindingResult bindingResult) {
               if (bindingResult.hasErrors()) {
                    return "spittles/edit";
               }
               spitterService.saveSpitter(spitter);
               return "redirect:/spitter/" + spitter.getUsername();
                }
             }

这是我的 Spitter类文件:

package com.habuma.spitter.domain;

import java.util.List;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

public class Spitter {
    private Long id;

    @Size(min = 3, max = 20, message = "User name must be between 3 and 20 characters long.")
    @Pattern(regexp = "^[a-zA-Z0-9]+$", message = "Username must be alphanumeric with no spaces")
    private String username;

    @Size(min = 6, max = 20, message = "The password must be atleast 6 characters long.")
    private String password;

    @Size(min = 3, max = 50, message = "Your full name must be between 3 and 50 characters long.")
    private String fullName;

    @Pattern(regexp = "[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}", message = "Invalid email address.")
    private String email;

    private List<Spittle> spittles;
    private boolean updateByEmail;

    ......Setters & Getters.....

    @Override
    public boolean equals(Object obj) {
        Spitter other = (Spitter) obj;
        return other.fullName.equals(fullName)
                && other.username.equals(username)
                && other.password.equals(password);
    }

    @Override
    public int hashCode() {
        return super.hashCode();
    }
}

这是我的 edit.jsp显示给用户注册的文件:

<%@ taglib prefix="sf" uri="http://www.springframework.org/tags/form"%>
<div>
    <h2>Create a free Spitter account</h2>
    <sf:form method="POST" modelAttribute="spitter" enctype="multipart/form-data">
        <fieldset>
            <table cellspacing="0">
                <tr>
                    <th><label for="user_full_name">Fullname:</label></th>
                    <td><sf:input path="fullName" size="15" id="user_full_name" />
                        <sf:errors path="fullName" cssClass="error" /></td>
                </tr>
                <tr>
                    <th><label for="user_screen_name">Username:</label></th>
                    <td><sf:input path="username" size="15" maxlength="15"
                            id="user_screen_name" /> <small id="username_msg">No spaces,please.</small>
                        <sf:errors path="username" cssClass="error" /></td>
                </tr>
                <tr>
                    <th><label for="user_password">Password:</label></th>
                    <td><sf:password path="password" size="30" showPassword="true"
                            id="user_password" /> <small>6
                            characters or more (betricky!)</small> <sf:errors path="password"
                            cssClass="error" /></td>
                </tr>
                <tr>
                    <th><label for="user_email">EmailAddress:</label></th>
                    <td><sf:input path="email" size="30" id="user_email" /> <small>In
                            case you forget something</small> <sf:errors path="email"
                            cssClass="error" /></td>
                </tr>
                <tr>
                    <th></th>
                    <td><sf:checkbox path="updateByEmail"
                            id="user_send_email_newsletter" /> <label
                        for="user_send_email_newsletter">Send me email updates!</label></td>
                </tr>
                <tr>
                    <th><label for="image">Profile image:</label></th>
                    <td><input name="image" type="file" />
                </tr>
                <tr>
                    <th></th>
                    <td><input name="commit" type="submit"
                        value="I accept.Createmyaccount." /></td>
                </tr>
            </table>
        </fieldset>
    </sf:form>
</div>

要加载表单，我访问的 URL 为:http://localhost:8081/SpringInAction3/spitter?new ，加载表单后，我只是提交表单而不输入任何详细信息，以便我可以检查我的表单是否得到验证。但是我遇到了以下异常:

java.lang.NullPointerException
    com.habuma.spitter.domain.Spitter.equals(Spitter.java:87)
    org.hibernate.validator.engine.resolver.SingleThreadCachedTraversableResolver$TraversableHolder.equals(SingleThreadCachedTraversableResolver.java:138)
    java.util.HashMap.get(HashMap.java:305)
    org.hibernate.validator.engine.resolver.SingleThreadCachedTraversableResolver.isReachable(SingleThreadCachedTraversableResolver.java:45)
    org.hibernate.validator.engine.ValidatorImpl.isValidationRequired(ValidatorImpl.java:757)
    org.hibernate.validator.engine.ValidatorImpl.validateConstraint(ValidatorImpl.java:324)
    org.hibernate.validator.engine.ValidatorImpl.validateConstraintsForRedefinedDefaultGroup(ValidatorImpl.java:273)
    org.hibernate.validator.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:256)
    org.hibernate.validator.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:210)
    org.hibernate.validator.engine.ValidatorImpl.validate(ValidatorImpl.java:119)
    org.springframework.validation.beanvalidation.SpringValidatorAdapter.validate(SpringValidatorAdapter.java:106)
    org.springframework.validation.DataBinder.validate(DataBinder.java:760)

我得到 NullPointerException在我的 equals Splitter的方法|类(class)。请让我知道我哪里做错了？

Edit:

当我尝试打印我的 Spitter 对象中字段的值时，我得到的所有字段均为空值，这导致了 NullPointerException .

这次我删除了 equals和 hashCode我的方法 Spitter类，现在当我提交表单时，验证没有发生，页面将转到 http://localhost:8081/SpringInAction3/spitter/null没有显示任何错误。

为什么在这种情况下没有进行验证？另外，如果我只是按照那本书中的步骤操作，我会得到 NullPointerException，这不是预期的。请让我知道我哪里做错了？

根据这篇 SO 帖子:@Valid (jsr 303) not working in Spring mvc 3.0 , 我也有标签 <mvc:annotation-driven/>在我的配置文件中。

Answer 1

到目前为止，我看到一个错误。 sf:form 属性 enctype 设置为 multipart/form-data 但它只用于文件上传，所以我猜 spring mvc 使用的是 MultipartResolver 而不是数据绑定(bind)将表单数据绑定(bind)到表单支持对象的机制，请尝试将其更改为 application/x-www-form-urlencoded，这是您的案例的默认和正确类型。