Spring boot详解fastjson过滤字段为null值如何解决

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.80</version>
</dependency>

/**
 * 返回值过滤器
 * 
 * @Author: 攻城狮白玉 https://blog.csdn.net/zhh763984017
 * @Date: 2022/7/09 18:05
 */
@Configuration
public class FastjsonConverterConfig {
    @Bean
    public HttpMessageConverters customConverters() {
        // 定义一个转换消息的对象
        FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
        // 添加fastjson的配置信息 比如 ：是否要格式化返回的json数据
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        // 这里就是核心代码了，WriteMapNullValue把空的值的key也返回
        fastJsonConfig.setSerializerFeatures(SerializerFeature.WriteMapNullValue);
        List<MediaType> fastMediaTypes = new ArrayList<MediaType>();
        // 处理中文乱码问题
        fastJsonConfig.setCharset(Charset.forName("UTF-8"));
        fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        fastConverter.setSupportedMediaTypes(fastMediaTypes);
        // 在转换器中添加配置信息
        fastConverter.setFastJsonConfig(fastJsonConfig);
        StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();
        stringConverter.setDefaultCharset(Charset.forName("UTF-8"));
        stringConverter.setSupportedMediaTypes(fastMediaTypes);
        // 将转换器添加到converters中
        return new HttpMessageConverters(stringConverter,fastConverter);
    }
}