在Spring中，默认的ObjectMapper是Jackson的JsonMapper，而不是XmlMapper。如果想避免在Spring中将Jackson的XmlMapper用作默认的ObjectMapper，可以进行如下解决方法：

1. 创建一个自定义的ObjectMapper bean，并将其配置为Spring的默认ObjectMapper。

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        return new ObjectMapper();
    }
}

2. 在自定义的ObjectMapper中禁用XML序列化和反序列化的功能。

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.disable(SerializationFeature.WRITE_DURATIONS_AS_TIMESTAMPS);
        objectMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
        objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
        objectMapper.disable(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        objectMapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
        objectMapper.setVisibility(PropertyAccessor.GETTER, JsonAutoDetect.Visibility.NONE);
        objectMapper.setVisibility(PropertyAccessor.IS_GETTER, JsonAutoDetect.Visibility.NONE);
        objectMapper.setVisibility(PropertyAccessor.SETTER, JsonAutoDetect.Visibility.NONE);
        objectMapper.setVisibility(PropertyAccessor.CREATOR, JsonAutoDetect.Visibility.NONE);
        return objectMapper;
    }
}

这样，就可以确保在Spring中，不会将Jackson的XmlMapper用作默认的ObjectMapper。