为什么不能覆盖掉原来的ObjectMapper？

Question

业务返回json格式，如果为null，要返回空字符串“”。

网上都是要注入一个ObjectMapper

@Configuration
public class ResultConfig {
    @Bean
    @Primary
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
            @Override
            public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) 
                    throws IOException, JsonProcessingException {
                jsonGenerator.writeString("");
            }
        });
        return objectMapper;
    }

可是还是不能覆盖掉 jacksonAutoConfig 配置的 ObjectMapper？这是为什么？

@Bean
        @Primary
        @ConditionalOnMissingBean
        ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
            return builder.createXmlMapper(false).build();
        }

@ConditionalOnMissingBean 不是应该没有这个bean才会生效吗？我已经注入了为什么默认的还会生效？

Answer 1

@ConditionalOnMissingBean 注解的bean没有生效，应该是加载顺序出现了问题，你控制一下bean的加载顺序试试