6、显示评论和回复

1、实体类：comment

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Comment {
    
    private int id;
    private int userId;
    private int entityType;
    private int entityId;
    private int targetId;
    private String content;
    private int status;
    private Date createTime;
}

2、数据层

CommentMapper接口

@Mapper
public interface CommentMapper {
    
    
    List<Comment> selectCommentsByEntity(int entityType, int entityId, int offset, int limit);

    int selectCountByEntity(int entityType, int entityId);
}

3、业务层

@Service
public class CommentService {
    
    
    @Autowired
    private CommentMapper commentMapper;
    
    public List<Comment> findCommentsByEntity(int entityType, int entityId, int offset, int limit){
    
        return commentMapper.selectCommentsByEntity(entityType, entityId, offset, limit);
    }

    public int findCommentCount(int entityType, int entityId){
    
        return commentMapper.selectCountByEntity(entityType, entityId);
    }

}

4、表现层

DiscussPostController
帖子详情页，有评论，评论中有回复
注入page，post，user，comments

    @RequestMapping(path = "/detail/{discussPostId}", method = RequestMethod.GET)
    public String getDiscussPost(@PathVariable("discussPostId") int discussPostId, Model model, Page page) {
    
        // 帖子
        DiscussPost post = discussPostService.findDiscussPostById(discussPostId);
        model.addAttribute("post", post);
        // 作者
        User user = userService.findUserById(post.getUserId());
        model.addAttribute("user", user);

        // 评论分页信息
        page.setLimit(5);
        page.setPath("/discuss/detail/" + discussPostId);
        page.setRows(post.getCommentCount());

        // 评论列表
        List<Comment> commentList = commentService.findCommentsByEntity(
                ENTITY_TYPE_POST, post.getId(), page.getOffset(), page.getLimit());
        // 评论显示vo列表
        List<Map<String, Object>> commentVoList = new ArrayList<>();
        if(commentList != null){
    
            for (Comment comment : commentList) {
    
                Map<String, Object> commentVo = new HashMap<>();
                commentVo.put("comment", comment);// 评论
                commentVo.put("user", userService.findUserById(comment.getUserId()));// 作者

                // 回复列表
                List<Comment> replyList = commentService.findCommentsByEntity(
                        ENTITY_TYPE_COMMENT, comment.getId(), 0, Integer.MAX_VALUE);
                // 回复显示vo列表
                List<Map<String, Object>> replyVoList = new ArrayList<>();
                if (replyList != null) {
    
                    for (Comment reply : replyList) {
    
                        Map<String, Object> replyVo = new HashMap<>();
                        replyVo.put("reply", reply);// 回复
                        replyVo.put("user", userService.findUserById(reply.getUserId()));// 作者
                        User target = reply.getTargetId() == 0 ? null : userService.findUserById(reply.getTargetId()); // 回复目标
                        replyVo.put("target", target);
                        replyVoList.add(replyVo);
                    }
                }
                commentVo.put("replys", replyVoList);

                // 回复数量
                int replyCount = commentService.findCommentCount(ENTITY_TYPE_COMMENT, comment.getId());
                commentVo.put("replyCount", replyCount);

                commentVoList.add(commentVo);
            }
        }

        model.addAttribute("comments", commentVoList);
        return "/site/discuss-detail";
    }

5、增加评论（更新评论数量，事务管理）

事务管理，声明式配置（整个），编程式（部分），这里采用声明式配置。@Transactional(隔离级别、传播机制）

@Transactional(
            isolation = Isolation.READ_COMMITTED,
            propagation = Propagation.REQUIRED,
            rollbackFor = Exception.class)
    public int 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()));
        int rows = commentMapper.insertComment(comment);

        // 更新帖子数量
        if(comment.getEntityType() == ENTITY_TYPE_POST){
    
            int count =
                    commentMapper.selectCountByEntity(comment.getEntityType(), comment.getEntityId());
            discussPostService.updateCommentCount(comment.getEntityId(), count);
        }
        return rows;
    }