SpringBoot开发十八-显示评论
需求介绍
显示评论，还是我们之前做的流程。
数据层：根据实体查询一页的评论数据，以及根据实体查询评论的数量
业务层：处理查询评论的业务，处理查询评论数量的业务
表现层：同时显示帖子详情数据时显示该帖子的所有的评论的数量和数据
代码介绍
首先新增一个实体类 Comment
package com.nowcoder.community.entity;
import java.util.Date;
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;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public int getEntityType() {
return entityType;
}
public void setEntityType(int entityType) {
this.entityType = entityType;
}
public int getEntityId() {
return entityId;
}
public void setEntityId(int entityId) {
this.entityId = entityId;
}
public int getTargetId() {
return targetId;
}
public void setTargetId(int targetId) {
this.targetId = targetId;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
@Override
public String toString() {
return "Comment{" +
"id=" + id +
", userId=" + userId +
", entityType=" + entityType +
", entityId=" + entityId +
", targetId=" + targetId +
", content='" + content + '\'' +
", status=" + status +
", createTime=" + createTime +
'}';
}
}
同理新建数据层 CommentMapper
package com.nowcoder.community.dao;
import com.nowcoder.community.entity.Comment;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper
public interface CommentMapper {
// 根据实体来查询到的评论，要分页
List<Comment> selectCommentsByEntity(int entityType, int entityId, int offset, int limit);
int selectCountByEntity(int entityType, int entityId);
}
然后编写对应的 comment-mapper.xml 实现对应的 sql 语句
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.nowcoder.community.dao.CommentMapper">
<sql id="selectFields">
id, user_id, entity_type, entity_id, target_id, content, status, create_time
</sql>
<select id="selectCommentsByEntity" resultType="Comment">
select <include refid="selectFields"></include>
from comment
where status = 0
and entity_type = #{entityType}
and entity_id = #{entityId}
order by create_time asc
limit #{offset}, #{limit}
</select>
<select id="selectCountByEntity" resultType="int">
select count(id)
from comment
where status = 0
and entity_type = #{entityType}
and entity_id = #{entityId}
</select>
</mapper>
然后写业务层 CommentService 调用数据层的方法
package com.nowcoder.community.service;
import com.nowcoder.community.dao.CommentMapper;
import com.nowcoder.community.entity.Comment;
import com.nowcoder.community.util.CommunityConstant;
import com.nowcoder.community.util.SensitiveFilter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.util.HtmlUtils;
import java.util.List;
@Service
public class CommentService implements CommunityConstant{
@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);
}
}
然后在帖子详情的页面，重构一下 getDiscussPost 方法，因为之前只是显示了帖子内容的详情，现在要增加对应的评论，所以重写一下对应的方法。
// 因为熟悉了 mysql 的表，我们知道我的评论是有着对应的实体类型评论，它是一个常量代表，所以要在我们确定好的常量接口里面声明这些常量，然后再去 CommentController 里面重构 getDiscussPost 方法
/**
* 实体类型：帖子
*/
int ENTITY_TYPE_POST = 1;
/**
* 实体类型：评论
*/
int ENTITY_TYPE_COMMENT = 2;
/**
* 实体类型: 用户
*/
int ENTITY_TYPE_USER = 3;
// 补充对应的评论的 commentService
@Autowired
private CommentService commentService;
@RequestMapping(path = "/detail/{discussPostId}", method = RequestMethod.GET)
public String getDiscussPost(@PathVariable("discussPostId") int discussPostId, Model model, Page page) {
DiscussPost discussPost = discussPostService.findDiscussPostById(discussPostId);
model.addAttribute("post", discussPost);
// 查帖子作者
User user = userService.findUserById(discussPost.getUserId());
model.addAttribute("user", user);
// 查评论分页信息
page.setLimit(5);
page.setPath("/discuss/detail/" + discussPostId);
page.setRows(discussPost.getCommentCount());
// 评论：给帖子的评论
// 回复：给评论的评论
// 评论列表
List<Comment> commentList = commentService.findCommentsByEntity(
1, discussPost.getId(), page.getOffset(), page.getLimit());
// 评论VO列表
List<Map<String, Object>> commentVoList = new ArrayList<>();
if (commentList != null) {
for (Comment comment : commentList) {
// 一个评论的VO
Map<String, Object> commentVo = new HashMap<>();
// 评论
commentVo.put("comment", comment);
// 作者
commentVo.put("user", userService.findUserById(comment.getUserId()));
// 回复列表
List<Comment> replyList = commentService.findCommentsByEntity(
ENTITY_TYPE_COMMENT, comment.getId(), 0, Integer.MAX_VALUE);
// 回复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);
replyVo.put("user", userService.findUserById(reply.getUserId()));
// 回复的目标
User target = reply.getTargetId() == 0 ? null : userService.findUserById(reply.getTargetId());
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";
}
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