spring boot-@Validated参数校验-自定义注解（不为空才进行正则校验）

import javax.validation.Constraint;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.Payload;
import java.lang.annotation.*;


@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = NotNullThenPattern.NotNullThenPatternValidation.class)
@documented
public @interface NotNullThenPattern {
    String regex() default "";

    String message() default "格式错误";

    Class[] groups() default {};

    Class[] payload() default {};

        
    class NotNullThenPatternValidation implements ConstraintValidator {

        private String regex;

        @Override
        public void initialize(NotNullThenPattern constraintAnnotation) {
            this.regex = constraintAnnotation.regex();
        }

        
        @Override
        public boolean isValid(String pattern, ConstraintValidatorContext constraintValidatorContext) {
            if (StringUtil.isBlank(pattern)) {
                return true;
            }
            if (regex.matches(pattern)) {
                return true;
            }
            return false;
        }

    }
}