User defined annotation verification API parameter phone number

annotation

Before creating annotations , Let's first clarify the logic of phone number verification , To achieve ：

1. Mobile number cannot be empty
2. Regular expression that conforms to the phone number
3. Check the length of the phone number

Create an interface

@Documented
@Constraint(validatedBy = PhoneNumberValidator.class)
@Target({ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface PhoneNumber {
    String message() default "Invalid phone number";
    Class<?>[] groups() default { };
    Class<? extends Payload>[] payload() default { };
}

Logic implementation

public class PhoneNumberValidator implements ConstraintValidator<PhoneNumber, String> {
	/**
	 * Implements the validation logic.
	 * The state of {@code value} must not be altered.
	 * <p>
	 * This method can be accessed concurrently, thread-safety must be ensured
	 * by the implementation.
	 *
	 * @param value object to validate
	 * @param context context in which the constraint is evaluated
	 *
	 * @return {@code false} if {@code value} does not pass the constraint
	 */

    @Override
    public boolean isValid(String phoneField, ConstraintValidatorContext context) {
        // can be null
        if (phoneField == null) return true;
        return phoneField != null && phoneField.matches("[0-9]+")
                && (phoneField.length() > 8) && (phoneField.length() < 14);
    }
}