如何使用构造函数中的Java验证器注释？

Question

I have value object that holds String . That String is subject to some restrictions (length, allowed characters, etc).

I would like to use Java or Spring validation API for validating my object. I would like to validate my domain object at creation time (in constructor).

Sample code that realises that (validates this using validation API):

void validate() {
        LocalValidatorFactoryBean localValidatorFactoryBean = new LocalValidatorFactoryBean();
        Set<ConstraintViolation<Msisdn>> violations = localValidatorFactoryBean.getValidator().validate(this);
        if (!violations.isEmpty()) {
            throw new ConstraintViolationException(violations);
        }
    }

I do not know how to get instance of javax.validation.Validator from constructor.

In Spring-managed code (service) I could just @Autowire instance of javax.validation.Validator or org.springframework.validation.Validator and it works.

But how to make it work outside of Spring-managed code (in constructor of value object, that stands on his own)?

I know that I can write validation rules using ifs, but validation annotations makes code much simpler.

Answer 1

Hibernate Validator documentation describes how to get instance of javax.validation.Validator

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

But it is not suitable to build ValidatorFactory in constructor. It is time-consuming operation. Maybe using cached reference in thrad-local would help, but I do not like that increased complexity.

Finally, I have decided to write validation rules for my value objects using Guava Preconditions

 Preconditions.checkNotNull(value, "value cannot be null");