Spring Boot之显示评论

1. 功能描述

• 数据层
  • 根据实体查询一页评论数据
  • 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
  • 显示帖子详情数据时，同时显示该帖子所有的评论数据

2. 实体类及相关映射

2.1 实体类 Comment

entity/Comment.java

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 +
                '}';
    }
}

2.1 XML 映射

mapper/comment-mapper.xml

<?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>

    <sql id="insertFields">
        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>

    <insert id="insertComment" parameterType="Comment">
        insert into comment(<include refid="insertFields"></include>)
        values(#{
    
    userId},#{
    
    entityType},#{
    
    entityId},#{
    
    targetId},#{
    
    content},#{
    
    status},#{
    
    createTime})
    </insert>

</mapper>

3. Dao

接口
dao/CommentMapper.java

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 {
    
    

    List<Comment> selectCommentsByEntity(int entityType, int entityId, int offset, int limit);

    int selectCountByEntity(int entityType, int entityId);

    int insertComment(Comment comment);

}

4. Service

service/CommentService.java

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;

    @Autowired
    private SensitiveFilter sensitiveFilter;

    @Autowired
    private DiscussPostService discussPostService;

    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);
    }

    @Transactional(isolation = Isolation.READ_COMMITTED, propagation = Propagation.REQUIRED)
    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);

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

5. Controller

controller/DiscussPostController.java

package com.nowcoder.community.controller;

import com.nowcoder.community.entity.Comment;
import com.nowcoder.community.entity.DiscussPost;
import com.nowcoder.community.entity.Page;
import com.nowcoder.community.entity.User;
import com.nowcoder.community.service.CommentService;
import com.nowcoder.community.service.DiscussPostService;
import com.nowcoder.community.service.UserService;
import com.nowcoder.community.util.CommunityConstant;
import com.nowcoder.community.util.CommunityUtil;
import com.nowcoder.community.util.HostHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import java.util.*;

@Controller
@RequestMapping("/discuss")
public class DiscussPostController implements CommunityConstant {
    
    

    @Autowired
    private DiscussPostService discussPostService;

    @Autowired
    private HostHolder hostHolder;

    @Autowired
    private UserService userService;

    @Autowired
    private CommentService commentService;

    @PostMapping("/add")
    @ResponseBody
    public String addDiscussPost(String title, String content) {
    
    
        User user = hostHolder.getUser();
        if (user == null) {
    
    
            return CommunityUtil.getJSONString(403, "你还没有登录哦!");
        }

        DiscussPost post = new DiscussPost();
        post.setUserId(user.getId());
        post.setTitle(title);
        post.setContent(content);
        post.setCreateTime(new Date());
        discussPostService.addDiscussPost(post);

        // 报错的情况,将来统一处理.
        return CommunityUtil.getJSONString(0, "发布成功!");
    }

    @GetMapping("/detail/{discussPostId}")
    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: 给帖子的评论
        // 回复: 给评论的评论
        // 评论列表
        List<Comment> commentList = commentService.findCommentsByEntity(
                ENTITY_TYPE_POST, post.getId(), page.getOffset(), page.getLimit());
        // 评论VO列表
        List<Map<String, Object>> commentVoList = new ArrayList<>();
        if (commentList != null) {
    
    
            for (Comment comment : commentList) {
    
    
                // 评论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<>();
                        // 回复
                        replyVo.put("reply", reply);
                        // 作者
                        replyVo.put("user", userService.findUserById(reply.getUserId()));
                        // 回复目标
                        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";
    }

}