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";

    }

巴特西

SpringBoot开发十八-显示评论

需求介绍

代码介绍

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