spring boot新闻管理项目——评论功能和按标签、类型显示新闻

本次实现了新闻页面的评论功能，能够对新闻进行评论和评论互动。同时也实现了点击新闻列表首页的分类和标签，可按分类和标签显示新闻的功能。

本次设计的难点主要集中在评论的展示功能，需将所有子评论展示到一个最初的父评论下，实现利用了递归思想。本次以评论功能的实现为例。

1. 设计

   po.Comment

   类，并在

   po.News

   类中添加相应的

   Comment

   类，并更新

   Setter

   、

   Getter

   和

   toString

   方法

   @Entity
   @Table(name = "t_comment")
   public class Comment {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Long id;
   private String nickname;
   private String email;
   private String content;
   private String avatar;
   @Temporal(TemporalType.TIMESTAMP)
   private Date createTime;
   @ManyToOne
   private News news;
   @OneToMany(mappedBy = "parentComment")
   private List<Comment> replyComments = new ArrayList<>();
   @ManyToOne
   private Comment parentComment;
   private boolean adminComment;
   
   public Comment() {
   }
   }

   添加

   List<Comment>

   数据

   @OneToMany(mappedBy = "news")
   private List<Comment> commentList = new ArrayList<>();

2. 创建

   dao/CommentRepository.java

   类，进行数据库操作

   public interface CommentRepository extends JpaRepository<Comment, Long> {
   
   List<Comment> findByNewsIdAndParentCommentNull(Long newsId, Sort sort);
   }

3. 创建

   service.impl.CommentServiceImpl.java

   类，提供保存评论和展示评论列表的任务

   @Service
   public class CommentServiceImpl implements CommentService {
   
   @Autowired
   private CommentRepository commentRepository;
   
   //提供展示评论的服务
   @Override
   public List<Comment> listCommentByNewsId(Long newsId) {
   Sort sort = Sort.by("createTime");
   List<Comment> comments = commentRepository.findByNewsIdAndParentCommentNull(newsId, sort);
   return eachComment(comments);
   }
   
   //遍历每条无父评论的评论
   private List<Comment> eachComment(List<Comment> comments) {
   List<Comment> commentsView = new ArrayList<>();
   for (Comment comment : comments) {
   Comment c = new Comment();
   BeanUtils.copyProperties(comment, c);
   commentsView.add(c);
   }
   //合并评论的各层子代到第一级子代集合中
   combineChildren(commentsView);
   return commentsView;
   }
   
   private void combineChildren(List<Comment> comments) {
   for (Comment comment : comments) {
   List<Comment> replys1 = comment.getReplyComments();
   for (Comment reply1 : replys1) {
   //循环迭代，找出子代，存放在临时tempReplys中
   recursively(reply1);
   }
   //将所有子孙评论放入一级子评论中
   comment.setReplyComments(tempReplys);
   //清除临时存放区
   tempReplys = new ArrayList<>();
   }
   }
   
   //定义临时存放区
   private List<Comment> tempReplys = new ArrayList<>();
   
   //递归将所有子评论存入临时存放区
   private void recursively(Comment comment) {
   tempReplys.add(comment);    //顶节点添加到临时存放区
   if (comment.getReplyComments().size() > 0) {
   List<Comment> replys = comment.getReplyComments();
   for (Comment reply : replys) {
   tempReplys.add(reply);
   if (reply.getReplyComments().size() > 0) {
   recursively(reply);
   }
   }
   }
   }
   
   //保存评论
   @Override
   public Comment saveComment(Comment comment) {
   Long parentCommentId = comment.getParentComment().getId();
   if (parentCommentId != -1) {
   comment.setParentComment(commentRepository.findById(parentCommentId).orElse(null));
   } else {
   comment.setParentComment(null);
   }
   comment.setCreateTime(new Date());
   return commentRepository.save(comment);
   }
   }

4. 创建

   com.llanero.news.web.CommentController.java

   类，通过

   Service

   包中提供的对象方法响应web端页面的请求

   @Controller
   public class CommentController {
   @Autowired
   private CommentService commentService;
   
   @Autowired
   private NewsService newsService;
   
   private String avatar = "https://gitee.com/llanero/share/raw/master/img/20200727182846.jpeg";
   
   @GetMapping("/comments/{newId}")
   public String comments(@PathVariable Long newId, Model model) {
   model.addAttribute("comments", commentService.listCommentByNewsId(newId));
   return "new::commentList";
   }
   
   @PostMapping("/comments")
   private String post(Comment comment, HttpSession session) {
   Long newsId = comment.getNews().getId();
   comment.setNews(newsService.getNews(newsId));
   User user = (User) session.getAttribute("user");
   if (user != null) {
   comment.setAdminComment(true);
   comment.setAvatar(avatar);
   } else {
   comment.setAvatar(avatar);
   }
   commentService.saveComment(comment);
   return "redirect:/comments/" + newsId;
   }
   }

5. 分类展示介绍

   创建

   web.TypeShowController

   类，进行分类展示新闻

   @Autowired
   private TypeService typeService;
   
   @Autowired
   private NewsService newsService;
   
   @GetMapping("/types/{id}")
   public String types(@PageableDefault(size = 8, sort = {"updateTime"}, direction = Sort.Direction.DESC) Pageable pageable,
   @PathVariable Long id, Model model) {
   List<Type> types = typeService.listTypeTop(20);
   if (id == -1) {
   id = types.get(0).getId();
   }
   NewsQuery newsQuery = new NewsQuery();
   newsQuery.setTypeId(id);
   model.addAttribute("types", types);
   model.addAttribute("page", newsService.listNews(pageable, newsQuery));
   model.addAttribute("activeTypeId", id);
   return "types";
   }

6. 项目运行测试