spring boot 잭 슨 반환 null 문제 해결

public class CustomBeanSerializerModifier extends BeanSerializerModifier {

    @Override
    public List<BeanPropertyWriter> changeProperties(SerializationConfig config,BeanDescription beanDesc,List<BeanPropertyWriter> beanProperties) {
        for (int i = 0; i < beanProperties.size(); i++) {
            BeanPropertyWriter writer = beanProperties.get(i);
            if (isArrayType(writer)) {
                writer.assignNullSerializer(new CustomNullJsonSerializers.NullArrayJsonSerializer());
            } else if (isStringType(writer)) {
                writer.assignNullSerializer(new CustomNullJsonSerializers.NullStringJsonSerializer());
            }else if (isNumberType(writer)) {
                writer.assignNullSerializer(new CustomNullJsonSerializers.NullNumberJsonSerializer());
            }else if (isBooleanType(writer)) {
                writer.assignNullSerializer(new CustomNullJsonSerializers.NullBooleanJsonSerializer());
            }else{
                writer.assignNullSerializer(new CustomNullJsonSerializers.NullObjectJsonSerializer());
            }
        }
        return beanProperties;
    }

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

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

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

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

public class CustomNullJsonSerializers {

    /**
     *          null 
     */
    public static class NullArrayJsonSerializer extends JsonSerializer<Object> {
        @Override
        public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
            jsonGenerator.writeStartArray();
            jsonGenerator.writeEndArray();
        }
    }

    /**
     *         null 
     */
    public static class NullStringJsonSerializer extends JsonSerializer<Object> {
        @Override
        public void serialize(Object value, JsonGenerator jsonGenerator,SerializerProvider serializerProvider) throws IOException {
            jsonGenerator.writeString("");
        }
    }

    /**
     *        null 
     */
    public static class NullNumberJsonSerializer extends JsonSerializer<Object> {
        @Override
        public void serialize(Object value, JsonGenerator jsonGenerator,SerializerProvider serializerProvider) throws IOException {
            jsonGenerator.writeNumber(0);
        }
    }

    /**
     *   boolean   null 
     */
    public static class NullBooleanJsonSerializer extends JsonSerializer<Object> {
        @Override
        public void serialize(Object value, JsonGenerator jsonGenerator,SerializerProvider serializerProvider) throws IOException {
            jsonGenerator.writeBoolean(false);
        }
    }

    /**
     *          null 
     */
    public static class NullObjectJsonSerializer extends JsonSerializer<Object> {
        @Override
        public void serialize(Object value, JsonGenerator jsonGenerator,SerializerProvider serializerProvider) throws IOException {
            jsonGenerator.writeNull();
        }
    }

}

public class JacksonHttpMessageConverter extends MappingJackson2HttpMessageConverter {

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

@Configuration
public class JacksonAutoConfigure {

    @Bean
    @Primary
    @ConditionalOnMissingBean(ObjectMapper.class)
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.setSerializerFactory(objectMapper.getSerializerFactory().withSerializerModifier(new CustomBeanSerializerModifier()));
        SerializerProvider serializerProvider = objectMapper.getSerializerProvider();
        serializerProvider.setNullValueSerializer(new CustomNullJsonSerializers.NullObjectJsonSerializer());
        return objectMapper;
    }
}