一、数据层

• 增加评论数据。
• 修改帖子的评论数量。

由Mybatis plus实现。

二、业务层

• 处理添加评论的业务：先增加评论、再更新帖子的评论数量。

DiscussPostService接口

public interface DiscussPostService extends IService<DiscussPost> {
   // ...
    boolean updateCommentCount(int id, int commentCount);
}

DiscussPostServiceImpl

@Service
public class DiscussPostServiceImpl extends ServiceImpl<DiscussPostMapper, DiscussPost>
    implements DiscussPostService{
  // ...
   @Override
    public boolean updateCommentCount(int id, int commentCount) {
        LambdaUpdateWrapper<DiscussPost> luw = new LambdaUpdateWrapper<>();
        luw.set(DiscussPost::getCommentCount,commentCount)
                .eq(DiscussPost::getId,id);
        return this.update(luw);
    }
}

CommentService接口

public interface CommentService extends IService<Comment> {
    // ...
    boolean addComment(Comment comment);
}

CommentServiceImpl

    @Override
    @Transactional(isolation = Isolation.READ_COMMITTED, propagation = Propagation.REQUIRED)
    public boolean addComment(Comment comment) {
        if (comment == null) {
            throw new IllegalArgumentException("参数不能为空!");
        }

        // 添加评论
        comment.setContent(HtmlUtils.htmlEscape(comment.getContent()));
        comment.setContent(sensitiveFilter.filter(comment.getContent()));
        boolean res = this.save(comment);

        // 更新帖子评论数量
        if (comment.getEntityType() == ENTITY_TYPE_POST) {
            int count = this.baseMapper.selectCountByEntity(comment.getEntityType(), comment.getEntityId());
            discussPostService.updateCommentCount(comment.getEntityId(), count);
        }

        return res;
    }

三、表现层

• 处理添加评论数据的请求。
• 设置添加评论的表单。
  CommentController

@Controller
@RequestMapping("/comment")
public class CommentController {

    @Autowired
    private CommentService commentService;

    @Autowired
    private HostHolder hostHolder;

    @RequestMapping(path = "/add/{discussPostId}", method = RequestMethod.POST)
    public String addComment(@PathVariable("discussPostId") int discussPostId, Comment comment) {
        comment.setUserId(hostHolder.getUser().getId());
        comment.setStatus(0);
        comment.setCreateTime(new Date());
        commentService.addComment(comment);

        return "redirect:/discuss/detail/" + discussPostId;
    }
}

页面处理，略。