用自定义类级注解校验两字段不能同时为空

news2024/9/23 11:16:17

背景：

有下面这么一个类，要校验两字段query、image不能同时为空，应该怎么实现？已知的@NotBlank等标签都只能检验单个字段。

import jakarta.validation.constraints.NotBlank;
import lombok.Data;
import org.springframework.http.codec.multipart.FilePart;

@Data
public class MultiModalQARequest {
。。。。

    /**
     * 用户提问
     */
    @NotBlank(message = "query不能为空")
    private String query;

    private FilePart image;

}

解决：

参考https://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/?v=8.0#section-class-level-constraints中的在这里插入图片描述
我有以下实现：

import jakarta.validation.Constraint;
import jakarta.validation.Payload;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Target({TYPE, ANNOTATION_TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy = {NotBothBlankValidator.class})
@Documented
public @interface NotBothBlank {

    String message() default "两个字段不能同时为空";

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

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

    String firstFieldName();

    String secondFieldName();
}

import com.zju.design.aiplatformdemo2.utils.StringUtil;
import jakarta.validation.ConstraintValidator;
import jakarta.validation.ConstraintValidatorContext;
import lombok.extern.slf4j.Slf4j;

import java.lang.reflect.Field;
import java.util.function.BiFunction;

@Slf4j
public class NotBothBlankValidator
        implements ConstraintValidator<NotBothBlank, Object> {

    private NotBothBlank constraintAnnotation;

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

    private static BiFunction<Object, Field, Boolean> isBlank = (object, field) ->
    {
        log.info("NotBothBlankValidator field type {}", field.getType());
        try {
            field.setAccessible(true);
            return (String.class.isAssignableFrom(field.getType()) ? StringUtil.isBlank((String) field.get(object)) : field.get(object) == null);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    };

    @Override
    public boolean isValid(Object validatedObject, ConstraintValidatorContext context) {
        if (validatedObject == null) {
            return true;
        }
        //通过反射拿到validatedObject对象的firstFieldName和secondFieldName字段的值,判断它们不能同时为空:
        try {
            Field firstField = validatedObject.getClass().getDeclaredField(constraintAnnotation.firstFieldName());
            Field secondField = validatedObject.getClass().getDeclaredField(constraintAnnotation.secondFieldName());
            return !(isBlank.apply(validatedObject, firstField) && isBlank.apply(validatedObject, secondField));
        } catch (Exception e) {
            log.error("NotBothBlankValidator error", e);
            throw new RuntimeException(e);
        }
    }
}