Spring and validation

IsoDateString.java

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

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

@Documented
@Constraint(validatedBy = IsoDateStringValidator.class)
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface IsoDateString {
    String message() default "date must be in ISO-8601 format YYYY-MM-DD";

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

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

IsoDateStringValidator.java

import lombok.extern.slf4j.Slf4j;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.time.LocalDate;
import java.time.format.DateTimeParseException;

@Slf4j
public class IsoDateStringValidator implements ConstraintValidator<IsoDateString, String> {

    public boolean isValid(String date, ConstraintValidatorContext context) {
        try {
            LocalDate.parse(date);
            return true;
        } catch (DateTimeParseException e) {
            log.error("Could not parse date {}, {}", date, e.getMessage());
            return false;
        }
    }

}

NonNegativeIntegerString.java

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

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

@Documented
@Constraint(validatedBy = NonNegativeIntegerStringValidator.class)
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface NonNegativeIntegerString {
    String message() default "must be a non negative number";

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

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

NonNegativeIntegerStringValidator.java

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.regex.Pattern;

public class NonNegativeIntegerStringValidator implements ConstraintValidator<NonNegativeIntegerString, String> {
    private static Pattern pattern = Pattern.compile("^[\\d]*$");

    public boolean isValid(String number, ConstraintValidatorContext context) {
        return number != null && pattern.matcher(number).matches();
    }
}