java - 如何解决 JSR-303 自定义 validator 中的依赖关系

Question

假设有一个像这样的自定义验证注释

@Target({ElementType.TYPE, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {ThirdPartyConstraintValidator.class}) 
@Documented
public @interface ThirdPartyConstraint {
   String message() default "Invalid";

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

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

以及相应的 validator 需要另一个服务

public class ThirdPartyConstraintValidator implements ConstraintValidator<ThirdPartyConstraint, Pojo> {

  private ThirdPartyService thirdPartyService;

  @Override
  public void initialize(ThirdPartyConstraint thirdPartyConstraint) {}

  @Override
  public boolean isValid(Pojo pojo, ConstraintValidatorContext constraintValidatorContext) {
    return thirdPartyService.isValid(pojo);
  }

  public void setThirdPartyService(ThirdPartyService thirdPartyService) {
    this.thirdPartyService = thirdPartyService;
  }
}

验证上下文使用 Hibernate 实现进行初始化，如下所示

ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();

// and then some bean is validated
validator.validate(new Pojo());

在后台validate方法调用class.newInstance()来获取 validator 实现。因此，在 ThirdPartyConstraintValidator 的情况下，永远不会注入(inject)依赖项 ThirdPartyService。

在没有任何框架的情况下使用 ValidationFactory 时，是否可以通过 setter 或构造函数将 ThirdPartyService 注入(inject)到 ThirdPartyConstraintValidator 中？

更新:

按照@matthias的回答，我更新了我的ValidatorFactory以在其中初始化ThirdPartyConstraintValidator

public <T extends ConstraintValidator<?, ?>> T getInstance(Class<T> aClass) {
   if (ThirdPartyConstraintValidator.class.equals(aClass)) {
      ThirdPartyConstraintValidator thirdPartyConstraintValidator = new ThirdPartyConstraintValidator();
      thirdPartyConstraintValidator.setThirdPartyService(new ThirdPartyService());
      return (T) thirdPartyConstraintValidator;
   }
   return null;
}

Answer 1

您可以实现自定义 ConstraintValidatorFactory 来设置您的依赖项。

参见BeanVal Spec或Hibernate Validator Doc

Validator v = Validation.byDefaultProvider().configure()
        .constraintValidatorFactory(new MyConstraintValidatorFactory())
        .buildValidatorFactory()
        .getValidator();

class MyConstraintValidatorFactory implements ConstraintValidatorFactory {

    public <T extends ConstraintValidator<?, ?>> T getInstance(final Class<T> arg0) {
        //do your stuff to set dependencies
        ...
    }

    public void releaseInstance(final ConstraintValidator<?, ?> arg0) {
        ...
    }
}