SpringBoot返回对象时,如何将Long类型转换为String

/**
 * 返回Long转换为String
 * @author Jingly
 */
public class JacksonMapper extends ObjectMapper {
  public JacksonMapper() {
    super();
    this.configure(JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN, true);
    this.configure(JsonGenerator.Feature.IGNORE_UNKNOWN, true);
    this.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    this.setSerializationInclusion(Include.NON_NULL);
    SimpleModule simpleModule = new SimpleModule();
    simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
    simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
    simpleModule.addSerializer(long.class, ToStringSerializer.instance);
    registerModule(simpleModule);
  }
}

/**
 * @author Jingly
 */
@Configuration
public class WebConfig implements WebMvcConfigurer {
  @Autowired
  private HttpMessageConverters httpMessageConverters;
  /**
   * MappingJackson2HttpMessageConverter 实现了HttpMessageConverter 接口，
   * httpMessageConverters.getConverters() 返回的对象里包含了MappingJackson2HttpMessageConverter
   * @return
   */
  @Bean
  public MappingJackson2HttpMessageConverter getMappingJackson2HttpMessageConverter() {
    return new MappingJackson2HttpMessageConverter(new JacksonMapper());
  }
  @Override
  public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
    converters.addAll(httpMessageConverters.getConverters());
  }
}

@Data
public class TestVO {
  private Long id;
}

{
    "id": "123456"
}