解决返回json格式数据value为null对应的key不显示问题，引发的No serializer found for class cn.hutool.json.JSONNull报错

最新推荐文章于 2025-11-24 02:07:59 发布

原创最新推荐文章于 2025-11-24 02:07:59 发布 · 8.1k 阅读

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#java

本文讲述了在使用Hutool JSONUtil处理对象中null值时遇到的`Noserializerfoundforclasscn.hutool.json.JSONNull`错误，通过添加自定义序列化器和deserializer，以及创建JsonConfig类解决，确保null值在JSON转换时不丢失关键字段。

No serializer found for class cn.hutool.json.JSONNull报错

问题：对象的value为null，但将json数据返回前端时key却不显示，使用的是Hutool-json类
解决方案
最终成功效果

问题：对象的value为null，但将json数据返回前端时key却不显示，使用的是Hutool-json类

@Override
    public Object query(BannerDto bannerDto) {
        if(StringUtil.isNotEmpty(bannerDto.getSortType()) && "sort".equals(bannerDto.getSortType())){
            PageHelper.startPage(bannerDto.getPage(),bannerDto.getPageSize(),"a.sort asc");
        }else {
            PageHelper.startPage(bannerDto.getPage(),bannerDto.getPageSize(),"a.create_time desc");
        }

        Page<BannerVo> list = bannerExtendsMapper.selectBySelective(bannerDto);
        PageInfo pageInfo = new PageInfo(list,5);
        result.setCode(Status.SUCCESS.getIndex());
        result.setMsg(Status.SUCCESS.getName());
        result.setData(pageInfo);
        return JSONUtil.parseObj(result);  // 使用的是Hutool-json
    }

后台查询结果浏览器前端返回
苦思冥想之下，突然发现Hutool的JSONUtil类提供了**JSONUtil.parseObj()**不忽略空值的方法，顿时“垂死病中惊坐起”，马上动手。
JSONUtil工具类

@Override
public Object query(BannerDto bannerDto) {
    if(StringUtil.isNotEmpty(bannerDto.getSortType()) && "sort".equals(bannerDto.getSortType())){
        PageHelper.startPage(bannerDto.getPage(),bannerDto.getPageSize(),"a.sort asc");
    }else {
        PageHelper.startPage(bannerDto.getPage(),bannerDto.getPageSize(),"a.create_time desc");
    }

    Page<BannerVo> list = bannerExtendsMapper.selectBySelective(bannerDto);
    PageInfo pageInfo = new PageInfo(list,5);
    result.setCode(Status.SUCCESS.getIndex());
    result.setMsg(Status.SUCCESS.getName());
    result.setData(pageInfo);
    return JSONUtil.parseObj(result, false); //添加false参数
}

曙光就在眼前，有点小激动，却没想到反转随时都在，还是报错了，但文章的重头戏也来了。

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class cn.hutool.json.JSONNull and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: cn.hutool.json.JSONObject["data"]->cn.hutool.json.JSONObject["list"]->cn.hutool.json.JSONArray[0]->cn.hutool.json.JSONObject["title3"])
	at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1191) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:313) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:71) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:33) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:722) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:643) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:33) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:722) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:643) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:33) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:722) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:643) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:33) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1396) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913) ~[jackson-databind-2.9.9.3.jar:2.9.9.3]
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:287) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
	at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:291) 
	……

解决方案

创建一个配置类，引入以下这段Bean即可。

package com.dgmall.config;

import cn.hutool.json.JSONNull;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.SimpleModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.io.IOException;

@Configuration
public class JsonConfig {
    @Bean
    public ObjectMapper objectMapper() {
        SimpleModule simpleModule = new SimpleModule();
        simpleModule.addSerializer(JSONNull.class, new JsonSerializer<JSONNull>(){
            @Override
            public void serialize(JSONNull jsonNull, JsonGenerator jsonGenerator
                    , SerializerProvider serializerProvider) throws IOException {
                jsonGenerator.writeNull();
            }
        });
        simpleModule.addDeserializer(JSONNull.class, new JsonDeserializer<JSONNull>() {
            @Override
            public JSONNull deserialize(JsonParser jsonParser
                    , DeserializationContext deserializationContext) {
                return null;
            }
        });
        return new ObjectMapper().registerModule(simpleModule);
    }
}