java注解-入参校验（标注于单个参数上）

1、创建注解，添加属性，采用@Constraint(validatedBy = {IfInEnumValidator.class})绑定注解实现类。

例：枚举校验

package com.yhsp.pay.model.aspect;

import com.yhsp.pay.common.enums.basenum.BaseEnum;
import com.yhsp.pay.model.aspect.impl.IfInEnumValidator;

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

/**
 * @author guocz
 * @date 20211123
 * 不为空判断是否在枚举中
 */
@Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {IfInEnumValidator.class})
public @interface IfInEnum {

    String message() default "枚举值不正确";

    Class<? extends BaseEnum> enumClass();

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

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

2、创建注解实现类，实现ConstraintValidator接口，用于注解绑定该类。

package com.yhsp.pay.model.aspect.impl;

import com.yhsp.pay.common.enums.basenum.BaseEnum;
import com.yhsp.pay.model.aspect.IfInEnum;
import org.apache.commons.lang3.StringUtils;
import org.hibernate.validator.internal.engine.constraintvalidation.ConstraintValidatorContextImpl;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

/**
 * @author guocz
 * @date 20211123
 * 不为空判断是否在枚举中
 */
public class IfInEnumValidator implements ConstraintValidator {

    @Override
    public void initialize(IfInEnum constraintAnnotation) {
    }

    @Override
    public boolean isValid(String s, ConstraintValidatorContext constraintValidatorContext) {
        if (StringUtils.isBlank(s)) {
            return true;
        }

        Class c = (Class) ((ConstraintValidatorContextImpl) constraintValidatorContext).getConstraintDescriptor().getAttributes().get("enumClass");
        BaseEnum[] baseEnum = (BaseEnum[]) c.getEnumConstants();
        for (BaseEnum e : baseEnum) {
            if (e.getKey().equals(s)) {
                return true;
            }
        }

        return false;
    }

}