java - 如何在 ConstraintValidator 中 Autowiring 服务

Question

我正在使用 Spring MVC 编写我的应用程序。我想验证用户注册时数据库中是否存在电子邮件。我编写了自己的注释约束，名为 UniqueEmail。

我的用户实体User.java:

@Entity
@Table(name="users")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "email", length = 100, nullable = false, unique = true)
    @NotEmpty
    @Email
    @UniqueEmail(message = "E-mail is not unique")
    private String email;

    @Column(name = "password", nullable = false)
    @NotEmpty
    @Size(min = 5, message = "size must be more 5")
    private String password;
}

我的注解约束UniqueEmail.java:

@Target({FIELD})
@Retention(RUNTIME)
@Constraint(validatedBy = UniqueEmailValidator.class)
@Documented
public @interface UniqueEmail {
    String message() default "Email is exist";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

我的 validator UniqueEmailValidator.java:

@Component
public class UniqueEmailValidator implements ConstraintValidator<UniqueEmail, String> {

    @Autowired
    private UserService userService;

    @Override
    public void initialize(UniqueEmail uniqueEmail) {
    }

    @Override
    public boolean isValid(String s, ConstraintValidatorContext constraintValidatorContext) {
        try {
            return userService.isExistEmail(s);
        } catch (Exception e) {
            System.out.println(e);
            return false;
        }
    }
}

此代码在应用程序中有效。

当我运行我的测试代码时，它返回 NullPointerException。在我的验证类中，userService 为空。

我读过 http://docs.spring.io/spring/docs/3.0.0.RC3/reference/html/ch05s07.html但无法解决。

有什么想法吗？

更新

我使用 JUnit。 UserClassTest.java

@ContextConfiguration("file:src/main/webapp/WEB-INF/mvc-dispatcher-servlet.xml")
public class UserClass {

    private static Validator validator;

    @BeforeClass
    public static void setup() {
        ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
        validator = factory.getValidator();
    }

    @Test
    public void emailIsUnique() {

        User user = new User();
        user.setEmail("mail@example.com"); // I've written exist email in DB.

        Set<ConstraintViolation<User>> constraintViolations = validator.validateProperty(user, "email");

        assertEquals(1, constraintViolations.size());
        assertEquals("E-mail is not unique", constraintViolations.iterator().next().getMessage());
    }
}

更新

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:mvc="http://www.springframework.org/schema/mvc"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

<context:component-scan base-package="ru.yadoka"/>

<import resource="db/db-config.xml"/>

<!-- Apache tiles -->
<bean id="tilesConfigurer"
      class="org.springframework.web.servlet.view.tiles3.TilesConfigurer">
    <property name="definitions">
        <list>
            <value>/WEB-INF/tiles.xml</value>
        </list>
    </property>
</bean>

<bean id="viewResolver"
      class="org.springframework.web.servlet.view.UrlBasedViewResolver">
    <property name="viewClass" value="org.springframework.web.servlet.view.tiles3.TilesView"/>
</bean>

<!-- Mapping resources from theme -->
<mvc:resources mapping="/css/**" location="/resources/css/"/>
<mvc:resources mapping="/js/**" location="/resources/js/"/>
<mvc:resources mapping="/fonts/**" location="/resources/
<mvc:annotation-driven/>

Answer 1

您的 bean 上下文中没有配置 validator 吗？如果您通过 Validation.buildDefaultValidatorFactory(); 引导 Validator，您将绕过 Spring 机制，并且您会得到一个不知道 Spring bean 和组件的 Validator。因此注入(inject)不起作用。在您的测试中，您希望获得 Spring 提供的 validator 。