javax.validation.ValidationException: HV000064: 无法实例化 ConstraintValidator

Question

我关注了this blog 的帖子并尝试实现自定义验证器来验证复合主键约束，但它失败了：

javax.validation.ValidationException: HV000064: Unable to instantiate ConstraintValidator: com.directory.domain.model.validators.StorePoolValidator.
    at com.directory.domain.repositories.StorePoolRepositoryTest.shouldReturnPoolByStore(StorePoolRepositoryTest.java:30)
Caused by: java.lang.NoSuchMethodException: com.directory.domain.model.validators.StorePoolValidator.<init>()
    at com.directory.domain.repositories.StorePoolRepositoryTest.shouldReturnPoolByStore(StorePoolRepositoryTest.java:30)

这里是验证器的注解接口代码：

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Retention(RUNTIME)
@Target({FIELD})
@Constraint(validatedBy = StorePoolValidator.class)
public @interface UniqueStorePoolConstraint {
    String message() default "Store pool validation failed";

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

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

这里是验证器类：

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.List;

public class StorePoolValidator implements ConstraintValidator<UniqueStorePoolConstraint, StorePoolId> {

    private StorePoolRepository storePoolRepository;

    public StorePoolValidator(StorePoolRepository storePoolRepository) {
        this.storePoolRepository = storePoolRepository;
    }

    @Override
    public void initialize(UniqueStorePoolConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(StorePoolId id, ConstraintValidatorContext context) {
        final List<StorePool> storePools = storePoolRepository.findAllByStoreNumber(id.getThirdNumber());

        return storePools.isEmpty();
    }
}

这里是实体类：

@Entity
@Getter
@Setter
@Builder
@AllArgsConstructor
@Table(name = "STORE_POOLS")
public class StorePool implements Serializable {

    public StorePool() {
    }

    @EmbeddedId
    @UniqueStorePoolConstraint
    private StorePoolId id;
}

及其主键类：

import javax.persistence.Column;
import javax.persistence.Embeddable;
import javax.validation.constraints.NotNull;
import java.io.Serializable;

@Getter
@Setter
@Builder
@ToString
@Embeddable
@EqualsAndHashCode
@AllArgsConstructor
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class StorePoolId implements Serializable {

    @Column(name = "pool", nullable = false)
    @NotNull
    private Integer pool;

    @Column(name = "third_number", nullable = false)
    @NotNull
    private Integer thirdNumber;
}

我尝试运行以下测试：

@RunWith(SpringRunner.class)
@DataJpaTest
public class StorePoolRepositoryTest {

    @Autowired
    private StorePoolRepository storePoolRepository;

    @Autowired
    private TestEntityManager entityManager;

    @Test
    public void shouldReturnPoolByStore() {
        final StorePool storePool = StorePoolBuilder.buildStorePool(1, 1);
        entityManager.persist(storePool);
        entityManager.flush();

        final List<StorePool> storePools = storePoolRepository.findAllByStoreNumber(1);

        assertThat(storePools).containsExactly(storePool);
    }
}

我错过了什么？谢谢。

Answer 1

抱歉，讨论晚了。

首先创建一个ContextProvider，它是你需要的bean的提供者。

@Component
public class ContextProvider implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        ContextProvider.applicationContext = applicationContext;
    }

    public static Object getBean(Class cls) {
        return ContextProvider.applicationContext.getBean(cls);
    }

}

现在你可以像这样拥有 bean：

ContextProvider.getBean(StorePoolRepository.class);

这解决了 NPE，您可以使用任何组件进行验证。

在您的情况下 StorePoolValidator，

@Service
public class StorePoolValidator implements ConstraintValidator<UniqueStorePoolConstraint, StorePoolId> {

    private StorePoolRepository storePoolRepository;

    @Override
    public void initialize(UniqueStorePoolConstraint constraintAnnotation) {
         this.storePoolRepository = (StorePoolRepository) ContextProvider.getBean(StorePoolRepository.class) 
    }

    @Override
    public boolean isValid(StorePoolId id, ConstraintValidatorContext context) {
        final List<StorePool> storePools = storePoolRepository.findAllByStoreNumber(id.getThirdNumber());

        return storePools.isEmpty();
    }
}

就是这样。

Answer 2

需要添加一个默认为空的构造函数StorePoolValidator才能初始化验证器。

public StorePoolValidator() {
}

更新

为了使用存储库，您可以将验证器添加为服务。那么答案是这样的：

@Service
public class StorePoolValidator implements ConstraintValidator<UniqueStorePoolConstraint, StorePoolId> {

    @Autowired
    private StorePoolRepository storePoolRepository;

    @Override
    public void initialize(UniqueStorePoolConstraint constraintAnnotation) {

    }

    @Override
    public boolean isValid(StorePoolId id, ConstraintValidatorContext context) {
        final List<StorePool> storePools = storePoolRepository.findAllByStoreNumber(id.getThirdNumber());

        return storePools.isEmpty();
    }
}

Answer 3

我遇到了基本相同的问题，但使用 Mock 测试时，我是这样解决的：

1. 这是我的自定义约束验证的样子：

   界面：

   @Target(ElementType.FIELD)
   @Retention(RetentionPolicy.RUNTIME)
   @Constraint(validatedBy = UniqueUsernameValidator.class)
   public @interface UniqueUsername {
   
    String message() default "This username is in use";
   
    Class<?>[] groups() default {};
   
    Class<? extends Payload>[] payload() default {};
   
   }
   

   实施：

    @RequiredArgsConstructor
    public class UniqueUsernameValidator implements ConstraintValidator<UniqueUsername, String> {
   
        private final UserRepository repository;
   
        @Override
        public boolean isValid(String username, ConstraintValidatorContext constraintValidatorContext) {
            return !repository.existsById(username);
        }
   }
   

2. 用@SpringBootTest注释你的测试类

3. 通过Spring配置设置MockMvc：

   @ExtendWith(MockitoExtension.class)
   @SpringBootTest
   public class RegistrationTest {
   
       @Autowired
       private WebApplicationContext wac;
   
       private MockMvc mockMvc;
   
       @BeforeEach
       void setUp() {
           this.mockMvc = MockMvcBuilders
                   .webAppContextSetup(wac)
                   .alwaysDo(print())
                   .build();
       }
   
       // your tests
   
   }
   

Answer 4

Spring 框架自动检测所有实现ConstraintValidator 接口的类。该框架将它们实例化并连接所有依赖项，就像该类是常规 Spring bean 一样。所以你不需要放@Service 和@Autowired 注释。 More details here.