SpringBoot - @JsonSerializer & @JsonInclude & @JsonIgnore

@JsonSerializer

• 全局类型重写，如：Date，对所有 Date 类型毫秒级转换到秒级。

package com.imooc.utils.serializer;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import java.io.IOException;
import java.util.Date;

public class Date2LongSerializer extends JsonSerializer<Date> {

    @Override
    public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
        jsonGenerator.writeNumber(date.getTime() / 1000);
    }
}

package com.imooc.dto;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.imooc.dataobject.OrderDetail;
import com.imooc.enums.OrderStatusEnum;
import com.imooc.enums.PayStatusEnum;
import com.imooc.utils.EnumUtil;
import com.imooc.utils.serializer.Date2LongSerializer;
import lombok.Data;
import java.math.BigDecimal;
import java.util.Date;
import java.util.List;

@Data
public class OrderDTO {

    /** 创建时间. */
    @JsonSerialize(using = Date2LongSerializer.class)
    private Date createTime;

    /** 更新时间. */
    @JsonSerialize(using = Date2LongSerializer.class)
    private Date updateTime;
}

@JsonInclude

• 使得返回为 null 的字段不显示在前台。

1、注解用法，@JsonSerializer 或 @JsonInclude

package com.imooc.dto;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.imooc.dataobject.OrderDetail;
import com.imooc.enums.OrderStatusEnum;
import com.imooc.enums.PayStatusEnum;
import com.imooc.utils.EnumUtil;
import com.imooc.utils.serializer.Date2LongSerializer;
import lombok.Data;
import java.math.BigDecimal;
import java.util.Date;
import java.util.List;

@Data
//@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL) // 已过期，可以用下面这条
@JsonInclude(JsonInclude.Include.NON_NULL)
public class OrderDTO {
    //...
}

2、yml 配置

spring:
  jackson:
    default-property-inclusion: non_null

@JsonIgnore

• 忽略被注解的字段一定不会显示在前台。

package com.imooc.dto;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.imooc.dataobject.OrderDetail;
import com.imooc.enums.OrderStatusEnum;
import com.imooc.enums.PayStatusEnum;
import com.imooc.utils.EnumUtil;
import com.imooc.utils.serializer.Date2LongSerializer;
import lombok.Data;
import java.math.BigDecimal;
import java.util.Date;
import java.util.List;

@Data
public class OrderDTO {

    @JsonIgnore
    public OrderStatusEnum getOrderStatusEnum() {
        return EnumUtil.getByCode(orderStatus, OrderStatusEnum.class);
    }

    @JsonIgnore
    public PayStatusEnum getPayStatusEnum() {
        return EnumUtil.getByCode(payStatus, PayStatusEnum.class);
    }
}