193 lines
5.7 KiB
Markdown
193 lines
5.7 KiB
Markdown
# 显示评论
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---
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解释一下评论表中的三个字段:
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- `entity_type`: 可以对帖子进行评论，也可以对该帖子的评论进行评论（回复） ，该字段就是用来表明评论目标的类别：1 帖子；2 评论
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- `entity_id`: 评论目标的 id。比如对 id 为 115 的 帖子进行评论，对 id 为 231 的评论进行评论
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- `target_id`: 指明我们这个回复是针对哪个用户的评论的（该字段只对回复生效，默认是 0）
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## DAO
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```java
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@Mapper
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public interface CommentMapper {
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/**
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* 根据评论目标（类别、id）对评论进行分页查询
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* @param entityType 评论目标的类别
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* @param entityId 评论目标的 id
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* @param offset 每页的起始索引
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* @param limit 每页显示多少条数据
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* @return
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*/
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List<Comment> selectCommentByEntity(int entityType, int entityId, int offset, int limit);
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/**
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* 查询评论的数量
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* @param entityType
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* @param entityId
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* @return
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*/
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int selectCountByEntity(int entityType, int entityId);
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}
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```
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对应的 `maaper.xml`
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```xml
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<mapper namespace="com.greate.community.dao.CommentMapper">
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<sql id = "selectFields">
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id, user_id, entity_type, entity_id, target_id, content, status, create_time
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</sql>
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<sql id = "insertFields">
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user_id, entity_type, entity_id, target_id, content, status, create_time
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</sql>
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<!--分页查询评论-->
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<!--不查询禁用的评论, 按照创建时间升序排序-->
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<select id = "selectCommentByEntity" resultType="Comment">
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select <include refid="selectFields"></include>
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from comment
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where status = 0
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and entity_type = #{entityType}
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and entity_id = #{entityId}
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order by create_time asc
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limit #{offset}, #{limit}
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</select>
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<!--查询评论的个数-->
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<select id = "selectCountByEntity" resultType="int">
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select count(id)
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from comment
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where status = 0
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and entity_type = #{entityType}
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and entity_id = #{entityId}
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</select>
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</mapper>
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```
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## Service
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```java
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@Service
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public class CommentService {
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@Autowired
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private CommentMapper commentMapper;
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/**
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* 根据评论目标（类别、id）对评论进行分页查询
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* @param entityType
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* @param entityId
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* @param offset
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* @param limit
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* @return
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*/
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public List<Comment> findCommentByEntity(int entityType, int entityId, int offset, int limit) {
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return commentMapper.selectCommentByEntity(entityType, entityId, offset, limit);
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}
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/**
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* 查询评论的数量
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* @param entityType
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* @param entityId
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* @return
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*/
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public int findCommentCount(int entityType, int entityId) {
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return commentMapper.selectCountByEntity(entityType, entityId);
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}
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}
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```
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## Controller
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在上篇的帖子详情中进行添加（复用分页组件）
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```java
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/**
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* 进入帖子详情页
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* @param discussPostId
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* @param model
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* @return
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*/
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@GetMapping("/detail/{discussPostId}")
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public String getDiscussPost(@PathVariable("discussPostId") int discussPostId, Model model, Page page) {
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// 帖子
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DiscussPost discussPost = discussPostSerivce.findDiscussPostById(discussPostId);
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model.addAttribute("post", discussPost);
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// 作者
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User user = userService.findUserById(discussPost.getUserId());
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model.addAttribute("user", user);
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// 评论分页信息
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page.setLimit(5);
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page.setPath("/discuss/detail/" + discussPostId);
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page.setRows(discussPost.getCommentCount());
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// 存储帖子的评论
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List<Comment> commentList = commentService.findCommentByEntity(
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ENTITY_TYPE_POST, discussPost.getId(), page.getOffset(), page.getLimit());
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List<Map<String, Object>> commentVoList = new ArrayList<>(); // 封装对帖子的评论和评论的作者信息
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if (commentList != null) {
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for (Comment comment : commentList) {
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// 对帖子的评论
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Map<String, Object> commentVo = new HashMap<>();
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commentVo.put("comment", comment);
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commentVo.put("user", userService.findUserById(comment.getUserId()));
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// 存储评论的评论（不做分页）
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List<Comment> replyList = commentService.findCommentByEntity(
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ENTITY_TYPE_COMMENT, comment.getId(), 0, Integer.MAX_VALUE);
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List<Map<String, Object>> replyVoList = new ArrayList<>(); // 封装对评论的评论和评论的作者信息
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if (replyList != null) {
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// 对评论的评论
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for (Comment reply : replyList) {
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Map<String, Object> replyVo = new HashMap<>();
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replyVo.put("reply", reply);
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replyVo.put("user", userService.findUserById(reply.getUserId()));
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User target = reply.getTargetId() == 0 ? null : userService.findUserById(reply.getUserId());
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replyVo.put("target", target);
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replyVoList.add(replyVo);
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}
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}
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commentVo.put("replys", replyVoList);
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// 对某个评论的回复数量
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int replyCount = commentService.findCommentCount(ENTITY_TYPE_COMMENT, comment.getId());
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commentVo.put("replyCount", replyCount);
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commentVoList.add(commentVo);
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}
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}
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model.addAttribute("comments", commentVoList);
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return "/site/discuss-detail";
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}
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```
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## 前端
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```html
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<li th:each="cvo:${comments}">
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<div th:utext="${cvo.comment.content}"></div>
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<li th:each="rvo:${cvo.replys}">
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<span th:text="${rvo.reply.content}"></span>
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```
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`cvoStat` 固定表达：循环变量名 + Stat 表示每次的循环对象
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`cvoStat.count` 表示当前是第几次循环 |