springboot返回值转成JSONString的处理方式

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
  @Override
  public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    super.configureMessageConverters(converters);
    //1.定义一个convert转换消息对象
    FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
    //2.添加fastjson的配置信息，比如：是否要格式化返回json数据
    FastJsonConfig fastJsonConfig = new FastJsonConfig();
    fastJsonConfig.setSerializerFeatures(
        SerializerFeature.PrettyFormat,
        SerializerFeature.WriteNullStringAsEmpty,
        SerializerFeature.DisableCircularReferenceDetect,
        SerializerFeature.WriteNullListAsEmpty
    );
    PropertyFilter propertyFilter = new PropertyFilter() {
      @Override
      public boolean apply(Object object, String name, Object value) {
        if (object instanceof MessageFor841 && value == null) {
          return false;
        }
        return true;
      }
    };
    fastJsonConfig.setSerializeFilters(propertyFilter);
    fastConverter.setFastJsonConfig(fastJsonConfig);
    converters.add(fastConverter);
  }
}

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.28</version>
        </dependency>

import com.alibaba.fastjson.JSON;

 HashMap<String, Object> data = new HashMap<>();
 List<MainMenu> mainMenus = menuDao.getMainMenus();
 data.put("data",mainMenus);
 data.put("status",200);
 String data_json = JSON.toJSONString(data);
 System.out.println("成功访问！！！");
 return data_json;