Spring Boot之添加评论

1. 功能描述

• 数据层
  • 增加评论数据
  • 修改帖子的评论数量
• 业务层
  • 处理添加评论的业务：先增加评论，再更新帖子的评论数量
• 表现层
  • 处理添加评论数据的请求
  • 设置添加评论的表单

2. 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. Service

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;
    }
}

4. Controller

controller/CommentController.java

package com.nowcoder.community.controller;

import com.nowcoder.community.entity.Comment;
import com.nowcoder.community.service.CommentService;
import com.nowcoder.community.util.HostHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import java.util.Date;

@Controller
@RequestMapping("/comment")
public class CommentController {
    
    

    @Autowired
    private CommentService commentService;

    @Autowired
    private HostHolder hostHolder;

    @PostMapping("/add/{discussPostId}")
    public String addComment(@PathVariable("discussPostId") int discussPostId, Comment comment) {
    
    
        comment.setUserId(hostHolder.getUser().getId());
        comment.setStatus(0);
        comment.setCreateTime(new Date());
        commentService.addComment(comment);

        return "redirect:/discuss/detail/" + discussPostId;
    }

}