spring - ConstraintValidator 依赖注入(inject)在类级别验证时会导致 ValidationException

Question

在 ConstraintValidator 中使用依赖注入(inject)时，我遇到了意外的行为。正在类里面进行评估。

实体类:

@Entity
@ValidDemoEntity
public class DemoEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

}

验证注释:

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {DemoEntityValidator.class})
public @interface ValidDemoEntity {

    String message() default "{some.demo.validator.message}";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};

}

validator :

public class DemoEntityValidator implements ConstraintValidator<ValidDemoEntity, DemoEntity> {

    private DemoEntityRepository demoEntityRepository;

    public DemoEntityValidator(DemoEntityRepository demoEntityRepository) {
        this.demoEntityRepository = demoEntityRepository;
    }

    @Override
    public void initialize(ValidDemoEntity constraintAnnotation) {

    }

    @Override
    public boolean isValid(DemoEntity demoEntity, ConstraintValidatorContext constraintValidatorContext) {
        return true;
    }
}

测试类:

@SpringBootTest
public class ValidatorInstantiationTest {

    private Validator validator;

    @Before
    public void setUp() throws Exception {
        ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
        validator = validatorFactory.getValidator();
    }

    @Test
    public void shouldInitiateAndCallDemoEntityValidator() {
        DemoEntity demoEntity = new DemoEntity();
        validator.validate(demoEntity);
    }

}

验证实体会导致:

javax.validation.ValidationException: HV000064: Unable to instantiate ConstraintValidator: com.example.demo.DemoEntityValidator.

并进一步向下堆栈跟踪:

Caused by: java.lang.NoSuchMethodException: com.example.demo.DemoEntityValidator.<init>()

这表明 Hibernate试图启动类(class)，而不是让 Spring 来处理。

奇怪的是，依赖注入(inject)适用于字段级别的验证。

代码位于 GitHub .

Answer 1

异常表示没有默认构造函数，因为 Hibernate Validator 尝试实例化您的 validator 。

你必须使用 Spring 。

1 使您的 validator 成为 Spring Bean:

@Component
public class DemoEntityValidator implements ConstraintValidator<ValidDemoEntity, DemoEntity> {

2 注入(inject) Spring 提供的 validator 并使用 SpringRunner 执行您的测试:

@SpringBootTest
@RunWith(SpringRunner.class)
public class ValidatorInstantiationTest {

    @Autowired
    private Validator validator;

    @Test
    public void shouldInitiateAndCallDemoEntityValidator() {
        DemoEntity demoEntity = new DemoEntity();
        validator.validate(demoEntity);
    }

}