实战编写高内聚低耦合的代码

故事是这样的，就是作品点赞数，评论数，转发量 缓存同步数据数量

原来队友没有同步数据库，导致排序不生效，现在要我处理

思路1

1. 直接在他们调用的地方 在集成数据库同步的代码，简单 代码越来越耦合 ，臃肿不堪 ，每个地方集成

思路2

1. 利用spring 事件机制，没个集成的地方，发布事件，观察者模式其实就是

思路3

1. 提供上下文操作发布事件方法，内聚起来，其他地方用 只需要 持有上下文对象就行，不需要每个地方再去 发布事件

代码演示

image.png

1. 内聚 调用方法

@Component
public class WorkEventContext {

    @Autowired
    private ApplicationContext applicationContext;

    /**
     * 作品 点赞事件
     * @param worksId
     * @param count
     */
    public void publishLikeEvent(Long worksId,Integer count){
        WorkLikeEvent workLikeEvent = new WorkLikeEvent();
        workLikeEvent.setWorkId(worksId);
        workLikeEvent.setLikeCount(count);
        applicationContext.publishEvent(workLikeEvent);
    }

    /**
     * 发布一个评论 事件
     * @param workId
     * @param count
     */
    public void publishDiscussEvent(Long workId,Integer count){
        WorkDiscussEvent workDiscussEvent = new WorkDiscussEvent();
        workDiscussEvent.setWorkId(workId);
        workDiscussEvent.setDiscussCount(count);
        applicationContext.publishEvent(workDiscussEvent);
    }


    /**
     * 作品转发 事件
     * @param workId
     * @param count
     */
    public void publishForwardEvent(Long workId,Integer count){
        WorkForwardEvent workForwardEvent = new WorkForwardEvent();
        workForwardEvent.setWorkId(workId);
        workForwardEvent.setForwardCount(count);
        applicationContext.publishEvent(workForwardEvent);
    }
}

2. 解耦 观察者

@Component
@Slf4j
public class WorkListener {

    @Autowired
    private WorksService worksService;

    /**
     *  点赞
     * @param event
     */
    @EventListener
    public void handleWorkLikeEvent(WorkLikeEvent event) {
        Long workId = event.getWorkId();
        Integer likeCount = event.getLikeCount();
        log.info("作品id:{},作品点赞数:{}",workId,likeCount);
        Works works = new Works();
        works.setId(workId);
        works.setLikeCount(likeCount);
        worksService.updateById(works);
    }


    /**
     *  评论
     * @param event
     */
    @EventListener
    public void handleWorkDiscussEvent(WorkDiscussEvent event) {
        Long workId = event.getWorkId();
        Integer discussCount = event.getDiscussCount();
        log.info("作品id:{},作品评论数:{}",workId,discussCount);
        Works works = new Works();
        works.setId(workId);
        works.setDiscussCount(discussCount);
        worksService.updateById(works);
    }


    /**
     *  转发
     * @param event
     */
    @EventListener
    public void handleWorkForwardEvent(WorkForwardEvent event) {
        Long workId = event.getWorkId();
        Integer forwardCount = event.getForwardCount();
        log.info("作品id:{},作品转发数:{}",workId,forwardCount);
        Works works = new Works();
        works.setId(workId);
        works.setForwardCount(forwardCount);
        worksService.updateById(works);
    }
}

3. 使用

image.png