枚举的使用及校验

今天聊聊枚举咋用

先定义一个枚举

package com.ruben.enumration;

import com.alibaba.fastjson.annotation.JSONType;
import com.fasterxml.jackson.annotation.JsonFormat;

/**
 * @ClassName: GenderEnum
 * @Description:
 * @Date: 2020/8/18 19:03
 * *
 * @author: achao<achao1441470436 @ gmail.com>
 * @version: 1.0
 * @since: JDK 1.8
 */
@JSONType(serializeEnumAsJavaBean = true)
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum GenderEnum {

    FEMALE("女", 0), MALE("男", 1);

    private String name;
    private Integer code;

    GenderEnum(String name, Integer code) {
        this.name = name;
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

}

然后就可以使用了

public static void main(String[] args) {
        System.out.println(GenderEnum.MALE.getName()+" "+GenderEnum.MALE.getCode());
        System.out.println(GenderEnum.FEMALE.getName()+" "+GenderEnum.FEMALE.getCode());
    }

输出结果

男 1
女 0

有人可能会问，枚举用Validator怎么校验？

其实也很简单

比如，我们接收的参数只能限制为枚举内有的0和1

这时就自定义一个校验

package com.ruben.validator;

import com.ruben.enumration.GenderEnum;

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

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * @ClassName: Gender
 * @Description:
 * @Date: 2020/8/18 19:25
 * *
 * @author: achao<achao1441470436 @ gmail.com>
 * @version: 1.0
 * @since: JDK 1.8
 */
@NotNull
@Documented
@Retention(RUNTIME)
@Constraint(validatedBy = {GenderValidator.class})
@ReportAsSingleViolation
@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
public @interface Gender {
    String message() default "性别应该为：男1 女0";

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

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

    GenderEnum[] value();

}

以及处理类

package com.ruben.validator;

import com.ruben.enumration.GenderEnum;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * @ClassName: GenderValidator
 * @Description:
 * @Date: 2020/8/18 19:25
 * *
 * @author: achao<achao1441470436 @ gmail.com>
 * @version: 1.0
 * @since: JDK 1.8
 */
public class GenderValidator implements ConstraintValidator<Gender, Integer> {

    private static final Set<Integer> GENDER_CONSTRAINTS = new HashSet<>();

    /**
     * Initializes the validator in preparation for
     *  calls.
     * The constraint annotation for a given constraint declaration
     * is passed.
     * <p>
     * This method is guaranteed to be called before any use of this instance for
     * validation.
     * <p>
     * The default implementation is a no-op.
     *
     * @param constraintAnnotation annotation instance for a given constraint declaration
     */
    @Override
    public void initialize(Gender constraintAnnotation) {
        GENDER_CONSTRAINTS.addAll(Arrays
                .stream(constraintAnnotation.value())
                .map(GenderEnum::getCode)
                .collect(Collectors.toSet()));
    }

    /**
     * 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(Integer value, ConstraintValidatorContext context) {
        return GENDER_CONSTRAINTS.contains(value);
    }
}