fastjson将对象转为json字符串给前端的时候, 如果字段的值为null, 则该字段默认被fastJson过滤直接不展示. 而在实际项目中我们往往也是需要展示这个字段的 , 解决即增加一个fastJson序列化配置 , 设置序列化格式.

package com.xbz.mvc.config;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;

import java.util.ArrayList;
import java.util.List;

/**
 * @title fastjson前端响应处理
 * @description 需要正常返回null值的字段
 * @author Xingbz
 * @createDate 2019-10-15
 */
@Configuration
public class FastJsonMvcConfig {

    @Bean
    public HttpMessageConverters fastJsonHttpMessageConverters() {
        //1.定义一个convert消息转换对象
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //2.添加fastJson的序列化配置信息
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat,
                SerializerFeature.DisableCircularReferenceDetect, SerializerFeature.WriteMapNullValue,
                SerializerFeature.WriteNullStringAsEmpty, SerializerFeature.WriteNullListAsEmpty);
        //3.处理中文乱码问题
        List<MediaType> fastMediaTypes = new ArrayList<>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        //4.在convert中添加配置信息
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        return new HttpMessageConverters(fastJsonHttpMessageConverter);

    }
}

fastJson序列化格式(SerializerFeature属性)配置如下 : 

更多更详细说明可参见此博文  https://blog.csdn.net/u010246789/article/details/52539576