SpringBoot设置Json返回字段为非空问题

/**
 * @作者 yangs
 * @日期 2022/1/20
 * @描述 json数据转化器
 */
public class JacksonHttpMessageConverter extends MappingJackson2HttpMessageConverter {

    /**
     * 处理数组类型的null值
     */
    public class NullArrayJsonSerializer extends JsonSerializer<Object> {

        @Override
        public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
            if (value == null) {
                jgen.writeStartArray();
                jgen.writeEndArray();
            }
        }
    }


    /**
     * 处理字符串类型的null值
     */
    public class NullStringJsonSerializer extends JsonSerializer<Object> {

        @Override
        public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
            jsonGenerator.writeString(StringUtils.EMPTY);
        }
    }

    /**
     * 处理数字类型的null值
     */
    public class NullNumberJsonSerializer extends JsonSerializer<Object> {

        @Override
        public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
            jsonGenerator.writeNumber(0);
        }
    }

    /**
     * 处理布尔类型的null值
     */
    public class NullBooleanJsonSerializer extends JsonSerializer<Object> {

        @Override
        public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
            jsonGenerator.writeBoolean(false);
        }
    }


    public class MyBeanSerializerModifier extends BeanSerializerModifier {

        @Override
        public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {
            //循环所有的beanPropertyWriter
            for (Object beanProperty : beanProperties) {
                BeanPropertyWriter writer = (BeanPropertyWriter) beanProperty;
                //判断字段的类型，如果是array，list，set则注册nullSerializer
                if (isArrayType(writer)) {
                    //给writer注册一个自己的nullSerializer
                    writer.assignNullSerializer(new NullArrayJsonSerializer());
                } else if (isNumberType(writer)) {
                    writer.assignNullSerializer(new NullNumberJsonSerializer());
                } else if (isBooleanType(writer)) {
                    writer.assignNullSerializer(new NullBooleanJsonSerializer());
                } else if (isStringType(writer)) {
                    writer.assignNullSerializer(new NullStringJsonSerializer());
                }
            }
            return beanProperties;
        }

        /**
         * 是否是数组
         */
        private boolean isArrayType(BeanPropertyWriter writer) {
            Class<?> clazz = writer.getType().getRawClass();
            return clazz.isArray() || Collection.class.isAssignableFrom(clazz);
        }

        /**
         * 是否是string
         */
        private boolean isStringType(BeanPropertyWriter writer) {
            Class<?> clazz = writer.getType().getRawClass();
            return CharSequence.class.isAssignableFrom(clazz) || Character.class.isAssignableFrom(clazz);
        }


        /**
         * 是否是int
         */
        private boolean isNumberType(BeanPropertyWriter writer) {
            Class<?> clazz = writer.getType().getRawClass();
            return Number.class.isAssignableFrom(clazz);
        }

        /**
         * 是否是boolean
         */
        private boolean isBooleanType(BeanPropertyWriter writer) {
            Class<?> clazz = writer.getType().getRawClass();
            return clazz.equals(Boolean.class);
        }

    }

    public JacksonHttpMessageConverter() {
        getObjectMapper().setSerializerFactory(getObjectMapper().getSerializerFactory().withSerializerModifier(new MyBeanSerializerModifier()));
    }

}

/**
 * @作者 yangs
 * @日期 2022/1/20
 * @描述 MVC的配置类
 */
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {

    // 文件映射路径
    @Value("${fileMappingPath}")
    private String fileMappingPath;

    /**
     * @作者 yangs
     * @日期 2022/1/20
     * @描述 返回给前端的json格式转化器
     */
    @Override
    protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        super.configureMessageConverters(converters);
        converters.add(new JacksonHttpMessageConverter());
    }
    
}

spring:
  mvc:
    static-path-pattern: /image/**
  resources:
    static-locations: file:E:/picture/

/**
 * @作者 yangs
 * @日期 2022/1/20
 * @描述 MVC的配置类
 */
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {

    /**
     * @作者 yangs
     * @日期 2022/1/20
     * @描述 返回给前端的json格式转化器
     */
    @Override
    protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        super.configureMessageConverters(converters);
        converters.add(new JacksonHttpMessageConverter());
    }

    // 文件映射路径
    @Value("${fileMappingPath}")
    private String fileMappingPath;

    /**
     * @作者 yangs
     * @日期 2022/1/20
     * @描述 配置静态资源访问路径
     */
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        //通过image获取静态资源
        registry.addResourceHandler("/image/**").addResourceLocations(fileMappingPath);
    }
}