自定义valida验证注解

@Target({ElementType.METHOD,ElementType.FIELD})  //注解作用域
@Retention(RetentionPolicy.RUNTIME)  //注解作用时间
@Constraint(validatedBy = MyConstriantValidator.class) //执行校验逻辑的类
public @interface MyConstraint {

    //校验不过时候的信息
    String message() default "{org.hibernate.validator.constraints.NotBlank.message}";

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

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

@Slf4j
public class MyConstriantValidator implements ConstraintValidator<MyConstraint,Object> {  //两个泛型分别为自定义注解和要校验的类型
    @Autowired  //可自由注入Spring工厂的bean
    private HelloService helloService;

    /**
     * 初始化
     * @param myConstraint
     */
    @Override
    public void initialize(MyConstraint myConstraint) {
        log.info("my validator init");
    }

    /**
     * 校验逻辑
     * @param o  //校验的参数
     * @param constraintValidatorContext
     * @return
     */
    @Override
    public boolean isValid(Object o, ConstraintValidatorContext constraintValidatorContext) {
        String value = helloService.sayHellp(o.toString());
        log.info(value);
        return false;
    }
}

   @MyConstraint(message = "这是一个测试")
    private String username;

    @PutMapping("/{id:\\d+}")
    public User update(@RequestBody @Valid User user,
                       BindingResult errors){  //这里BindingResult参数必须紧跟被@Valid注解的参数
        if(errors.hasErrors()){
            errors.getAllErrors().stream().forEach(error -> {
              //  FieldError fieldError = (FieldError) error;
              //  String message = fieldError.getField()+" "+error.getDefaultMessage();
                log.info(error.getDefaultMessage());
            });
        }
        return user;
    }