SpringBoot Controllerがjsonに返すnullを空白列または0に置き換える

public class NewsPo {
    private String  id;
    private String  title;
    private String  content;
    private String  path;
}

テストコントローラ:

@Controller
public class OrderCtl {
   @ResponseBody
    @RequestMapping("/getNewsList")
    public List getNewsList() {
        List list = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            NewsPo newsPo = new NewsPo();
            newsPo.setId(String.valueOf(i));
            newsPo.setPath("www.baidu.com");
            list.add(newsPo);
        }
        return list;
    }

}

 

      
[
    {
        "id":"0",
        "title":null,
        "content":null,
        "path":"www.baidu.com"
    },
    {
        "id":"1",
        "title":null,
        "content":null,
        "path":"www.baidu.com"
    },
    {
        "id":"2",
        "title":null,
        "content":null,
        "path":"www.baidu.com"
    },
    {
        "id":"3",
        "title":null,
        "content":null,
        "path":"www.baidu.com"
    },
    {
        "id":"4",
        "title":null,
        "content":null,
        "path":"www.baidu.com"
    }
]

jsonのnullを「」または0に変換します.次のコードを設定します.

@Configuration
public class JsonConfig {

    private Logger logger = LoggerFactory.getLogger(JsonConfig.class);

    @Bean
    @Primary
    @ConditionalOnMissingBean(ObjectMapper.class)
    public ObjectMapper objectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        SerializerProvider serializerProvider = objectMapper.getSerializerProvider();
        serializerProvider.setNullValueSerializer(new NullSerializer());
        logger.info(" objectMapper");
        return objectMapper;
    }


    public class NullSerializer extends JsonSerializer

      
[
    {
        "id":"0",
        "title":"",
        "content":"",
        "path":"www.baidu.com"
    },
    {
        "id":"1",
        "title":"",
        "content":"",
        "path":"www.baidu.com"
    },
    {
        "id":"2",
        "title":"",
        "content":"",
        "path":"www.baidu.com"
    },
    {
        "id":"3",
        "title":"",
        "content":"",
        "path":"www.baidu.com"
    },
    {
        "id":"4",
        "title":"",
        "content":"",
        "path":"www.baidu.com"
    }
]