求大神赐教Mapper mapper.map

@Resource
private Mapper mapper;
表示什么意思

@Override
public CxbbabaUserInfoModel getUserInfoByUserId(Long userId){
Criterion criterion = and(CxbbabaUserinfoEntity.UserID.eq(userId));
CxbbabaUserinfoEntity entity = userInfoRepository.where(criterion).singleOrDefault();
if (entity != null) {
return mapper.map(entity, CxbbabaUserInfoModel.class);
}
return null;
}
这段代码每行各代表什么意思？？？特别是return mapper.map(entity, CxbbabaUserInfoModel.class);这行代码，表示的是什么意思？？？？