SpringBoot整合Mybatis-plus实现多级评论功能

<!-- SpringBoot依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>${spring-boot-version}</version>
</dependency>
<!-- Mybatis-plus依赖 -->
<dependency>
    <groupId>com.baomidou.mybatisplus</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>${mybatis-plus-version}</version>
</dependency>
<!-- MySQL驱动 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>${mysql-version}</version>
</dependency>

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/dbname?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    username: root
    password: root
  # Mybatis-plus配置
  mybatis-plus:
    # 实体包路径
    typeAliasesPackage: cn.example.entity
    # Mybatis XML文件位置
    mapperLocations: classpath:mapper/*.xml
    # 自动填充策略
    global-config:
      db-config:
        id-type: auto
        field-strategy: not_empty

@Data
public class User {
    private Long id;
    private String username;
    private String password;
    private String email;
    private String avatar;
}
@Data
public class Comment {
    private Long id;
    private String content;
    private Date createTime;
    private Long parentId;
    private Long userId;
}

public interface UserMapper extends BaseMapper<User> {
}
public interface CommentMapper extends BaseMapper<Comment> {
    /**
     * 获取一级评论列表（即parent_id为null的评论）
     * @return 一级评论列表
     */
    List<Comment> listParentComments();
    /**
     * 获取二级评论列表（即parent_id不为null的评论）
     * @param parentId 父级评论ID
     * @return 二级评论列表
     */
    List<Comment> listChildComments(Long parentId);
}

@Service
public class CommentService {
    @Autowired
    private CommentMapper commentMapper;
    /**
     * 获取一级评论列表
     * @return 一级评论列表
     */
    public List<Comment> listParentComments() {
        return commentMapper.listParentComments();
    }
    /**
     * 获取二级评论列表
     * @param parentId 父级评论ID
     * @return 二级评论列表
     */
    public List<Comment> listChildComments(Long parentId) {
        return commentMapper.listChildComments(parentId);
    }
    /**
     * 添加评论
     * @param comment 评论信息
     */
    public void addComment(Comment comment) {
        commentMapper.insert(comment);
    }
}

@RestController
@RequestMapping("/comment")
public class CommentController {
    @Autowired
    private CommentService commentService;
    /**
     * 获取一级评论列表
     * @return 一级评论列表
     */
    @GetMapping("/parent")
    public ResultVo listParentComments() {
        List<Comment> comments = commentService.listParentComments();
        return ResultUtil.success(comments);
    }
    /**
     * 获取二级评论列表
     * @param parentId 父级评论ID
     * @return 二级评论列表
     */
    @GetMapping("/child")
    public ResultVo listChildComments(@RequestParam Long parentId) {
        List<Comment> comments = commentService.listChildComments(parentId);
        return ResultUtil.success(comments);
    }
    /**
     * 添加评论
     * @param comment 评论信息
     */
    @PostMapping("/add")
    public ResultVo addComment(@RequestBody Comment comment) {
        comment.setCreateTime(new Date());
        commentService.addComment(comment);
        return ResultUtil.success();
    }
}

<template>
  <div class="comment-box">
    <h2>评论区域</h2>
    <h3>发表评论</h3>
    <form @submit.prevent="addComment">
      <div class="form-item">
        <label>评论内容：</label>
        <textarea v-model="comment.content" required></textarea>
      </div>
      <button type="submit">提交</button>
    </form>
    <h3>一级评论</h3>
    <ul>
      <li v-for="comment in parentComments" :key="comment.id">
        <p>{{comment.content}}</p>
        <button @click="showChildComments(comment.id)">查看回复</button>
        <div v-show="showChildCommentId === comment.id">
          <h4>二级评论</h4>
          <ul>
            <li v-for="comment in childComments" :key="comment.id">
              <p>{{comment.content}}</p>
            </li>
          </ul>
        </div>
      </li>
    </ul>
  </div>
</template>
<script>
import axios from 'axios';
export default {
  data() {
    return {
      comment: {
        content: '',
      },
      parentComments: [],
      childComments: [],
      showChildCommentId: null,
    };
  },
  methods: {
    // 获取一级评论列表
    getParentComments() {
      axios.get('/comment/parent').then(res => {
        this.parentComments = res.data.data;
      }).catch(err => {
        console.log(err);
      });
    },
    // 获取二级评论列表
    getChildComments(parentId) {
      axios.get('/comment/child', {params: {parentId}}).then(res => {
        this.childComments = res.data.data;
      }).catch(err => {
        console.log(err);
      });
    },
    // 添加评论
    addComment() {
      axios.post('/comment/add', this.comment).then(res => {
        this.comment.content = '';
        this.getParentComments();
      }).catch(err => {
        console.log(err);
      });
    },
    // 显示二级评论
    showChildComments(parentId) {
      if(this.showChildCommentId === parentId) {
        this.showChildCommentId = null;
        this.childComments = [];
      }else {
        this.showChildCommentId = parentId;
        this.getChildComments(parentId);
      }
    }
  },
};
</script>
<style>
.comment-box {
  font-family: Arial, sans-serif;
  max-width: 800px;
  margin: auto;
}
.form-item {
  margin-top: 10px;
}
.form-item label {
  display: inline-block;
  width: 80px;
  font-weight: bold;
}
.form-item textarea {
  width: 100%;
  height: 100px;
  border: 1px solid #ccc;
}
ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
li {
  margin-top: 10px;
}
li p {
  margin: 0;
  padding: 5px;
  border: 1px solid #ccc;
  border-radius: 3px;
}
</style>