利用接口进行代码复用

userQueryServicepublic interface UserQueryService {
    public Map<Long, UserDTO> queryUserMap(List<? extends UserIdFunction> list);
}

public interface UserIdFunction {
    Long getUserId();
}

获取userId的复用代码

主义泛型参数

@Slf4j
@Service
public class UserQueryServiceImpl implements UserQueryService {
​
    @Autowired
    private UserClient userClient;
​
     @Override
    public Map<Long, UserDTO> queryUserMap(List<? extends UserIdFunction> list) {
        List<Long> userIds = list.stream().map(UserIdFunction::getUserId).distinct().collect(Collectors.toList());
        List<UserDTO> users = userClient.queryUserByIds(userIds);
        if (CollUtils.isEmpty(users)) {
            log.info("查询不到用户信息：{}", userIds);
            throw new BizIllegalException("网络异常");
        }
        Map<Long, UserDTO> userMap = users.stream().collect(Collectors.toMap(UserDTO::getId, Function.identity()));
        return CollUtils.isEmpty(userMap) ? new HashMap<>() : userMap;
    }
}

使用的时候，先注入userQueryService，让boardList中的实体类继承UserIdFunction

Map<Long, UserDTO> userMap = userQueryService.queryUserMap(boardList);