SpringBoot将Controller返回json中的null替换为空串或者0

系统管理员 2022-03-29 12:10 1077阅读 0赞

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

测试控制器：

@Controller
    public class OrderCtl {
       @ResponseBody
        @RequestMapping("/getNewsList")
        public List<NewsPo> getNewsList() {
            List<NewsPo> 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"
        }
    ]

要将json中的null转化为""或者0；配置如下代码即可

@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("注入objectMapper");
            return objectMapper;
        }
    
    
        public class NullSerializer extends JsonSerializer<Object> {
            @Override
            public void serialize(Object value, JsonGenerator jsonGenerator, SerializerProvider provider)
                    throws IOException {
                jsonGenerator.writeString("");
            }
        }
    }

[
        {
            "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"
        }
    ]