9.MongoDB Demo

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文章评论

1.需求分析

文章评论功能

需要实现以下功能:

  1. 基本增删改查API
  2. 根据文章id查询评论
  3. 评论点赞

2.数据库设计

表: articledb

字段名称 字段含义 字段类型 备注
_id ID ObjectId或String Mongo的主键的字段
articleid 文章ID String
content 评论内容 String
userid 评论人ID String
nickname 评论人昵称 String
createdatetime 评论的日期时间 Date
likenum 点赞数 Int32
replynum 回复数 Int32
state 状态 String 0：不可见；1：可见；
parentid 上级ID String 如果为0表示文章的顶级评论

3.使用技术

(1) mongodb-driver

mongodb-driver 是 mongo 官方推出的 java 连接 mongoDB 的驱动包，相当于 JDBC 驱动。我们通过一个入门的案例来了解 mongodb-driver 的基本使用

(2) SpringDataMongoDB

SpringData 家族成员之一，用于操作 MongoDB 的持久层框架，封装了底层的 mongodb-driver

4.项目搭建

(1) 新建一个 SpringBoot 或 Maven 工程

(2) pom.xml 文件引入依赖

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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/>
        <!-- lookup parent from repository -->
    </parent>

    <groupId>org.example</groupId>
    <artifactId>article</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-commons</artifactId>
            <version>2.4.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-commons</artifactId>
            <version>2.2.3.RELEASE</version>
        </dependency>

    </dependencies>

</project>

(3) 创建 application.yml

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spring:
  data:
    mongodb:
      host: 192.168.76.128
      port: 27017
      database: articledb
      # 或者通过uri 方式连接
      # uri: mongodb://192.168.76.128:27017/articledb

(4) 创建启动类

运行启动类，看项目能否正常启动

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package com.learn.article;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ArticleApplication {
    public static void main(String[] args) {
        SpringApplication.run(ArticleApplication.class);
    }
}

(5) 创建实体类

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package com.learn.article.po;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.index.Indexed;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.Field;
import java.io.Serializable;
import java.time.LocalDateTime;
import java.util.Date;
/**
 * 文章评论实体类
 */
// 把一个java类声明为mongodb的文档，可以通过collection参数指定这个类对应的文档。
// @Document(collection="mongodb 对应 collection 名")
// 可以省略，如果省略，则默认使用类名小写映射集合
@Document(collection="comment")
// 复合索引
// @CompoundIndex( def = "{'userid': 1, 'nickname': -1}")
public class Comment implements Serializable {
    // 主键标识，该属性的值会自动对应mongodb的主键字段"_id"，如果该属性名就叫“id”,则该注解可以省略，否则必须写
    @Id
    private String id;  // 主键
    // 该属性对应mongodb的字段的名字，如果一致，则无需该注解
    @Field("content")
    private String content;     // 吐槽内容
    private Date publishtime;   // 发布日期
    // 添加了一个单字段的索引
    @Indexed
    private String userid;      // 发布人ID
    private String nickname;    // 昵称
    private LocalDateTime createdatetime;   // 评论的日期时间
    private Integer likenum;    // 点赞数
    private Integer replynum;   // 回复数
    private String state;       // 状态
    private String parentid;    // 上级ID
    private String articleid;

    // getter and setter
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public Date getPublishtime() {
        return publishtime;
    }
    public void setPublishtime(Date publishtime) {
        this.publishtime = publishtime;
    }
    public String getUserid() {
        return userid;
    }
    public void setUserid(String userid) {
        this.userid = userid;
    }
    public String getNickname() {
        return nickname;
    }
    public void setNickname(String nickname) {
        this.nickname = nickname;
    }
    public LocalDateTime getCreatedatetime() {
        return createdatetime;
    }
    public void setCreatedatetime(LocalDateTime createdatetime) {
        this.createdatetime = createdatetime;
    }
    public Integer getLikenum() {
        return likenum;
    }
    public void setLikenum(Integer likenum) {
        this.likenum = likenum;
    }
    public Integer getReplynum() {
        return replynum;
    }
    public void setReplynum(Integer replynum) {
        this.replynum = replynum;
    }
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
    public String getParentid() {return parentid;
    }
    public void setParentid(String parentid) {
        this.parentid = parentid;
    }
    public String getArticleid() {
        return articleid;
    }
    public void setArticleid(String articleid) {
        this.articleid = articleid;
    }

    @Override
    public String toString() {
        return "Comment{" +
                "id='" + id + '\'' +
                ", content='" + content + '\'' +
                ", publishtime=" + publishtime +
                ", userid='" + userid + '\'' +
                ", nickname='" + nickname + '\'' +
                ", createdatetime=" + createdatetime +
                ", likenum=" + likenum +
                ", replynum=" + replynum +
                ", state='" + state + '\'' +
                ", parentid='" + parentid + '\'' +
                ", articleid='" + articleid + '\'' +
                '}';
    }

}

说明：

索引可以大大提升查询效率，一般在查询字段上添加索引，索引的添加可以通过 Mongo 的命令来添加，也可以在 Java 的实体类中通过注解添加

1）单字段索引注解 @Indexed ( org.springframework.data.mongodb.core.index.Indexed.class )

2）复合索引注解 @CompoundIndex ( org.springframework.data.mongodb.core.index.CompoundIndex.class )

5.基本增删改查

(1) 新建 Dao

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package com.learn.article.dao;

import com.learn.article.po.Comment;
import org.springframework.data.mongodb.repository.MongoRepository;

public interface CommentRepository extends MongoRepository<Comment, String> {

}

(2) 新建 Service

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package com.learn.article.service;

import com.learn.article.dao.CommentRepository;
import com.learn.article.po.Comment;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CommentService {

    @Autowired
    private CommentRepository commentRepository;

    /**
     * 保存一个评论
     * @param comment
     */
    public void saveComment(Comment comment) {
        //如果需要自定义主键，可以在这里指定主键；如果不指定主键，MongoDB会自动生成主键
        commentRepository.save(comment);
    }

    /**
     * 更新评论
     * @param comment
     */
    public void updateComment(Comment comment) {
        commentRepository.save(comment);
    }

    /**
     * 根据 id 删除评论
     * @param id
     */
    public void deleteCommentById(String id) {
        commentRepository.deleteById(id);
    }

    /**
     * 查询所有评论
     * @return
     */
    public List<Comment> findCommentList() {
        return commentRepository.findAll();
    }

    /**
     * 根据id查询评论
     * @param id
     * @return
     */
    public Comment findCommentById(String id) {
        return commentRepository.findById(id).get();
    }
}

(3) 新建 JUnit 测试类

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package com.learn.article.service;

import com.learn.article.ArticleApplication;
import com.learn.article.po.Comment;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.time.LocalDateTime;
import java.util.List;

// SpringBoot的Junit集成测试
@RunWith(SpringRunner.class)
// SpringBoot的测试环境初始化，参数：启动类
@SpringBootTest(classes = ArticleApplication.class)
public class CommentServiceTest {

    @Autowired
    private CommentService commentService;

    @Test
    public void testFindCommentList() {
        List<Comment> commentList = commentService.findCommentList();
        for (int i = 0; i < commentList.size(); i++) {
            System.out.println(commentList.get(i));
        }
//        Comment{id='1', content='我们不应该把清晨浪费在手机上，健康很重要，一杯温水幸福你我他。', publishtime=null, userid='1002', nickname='相忘于江湖', createdatetime=1970-01-01T08:00, likenum=1000, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='2', content='我夏天空腹喝凉开水，冬天喝温开水', publishtime=null, userid='1005', nickname='伊人憔悴', createdatetime=1970-01-01T08:00, likenum=888, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='3', content='我一直喝凉开水，冬天夏天都喝。', publishtime=null, userid='1004', nickname='杰克船长', createdatetime=2019-08-06T09:05:06.321, likenum=666, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='4', content='专家说不能空腹吃饭，影响健康。', publishtime=null, userid='1003', nickname='凯撒', createdatetime=2019-08-06T16:18:35.288, likenum=2000, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='5', content='研究表明，刚烧开的水千万不能喝，因为烫嘴。', publishtime=null, userid='1003', nickname='凯撒', createdatetime=2019-08-06T19:01:02.521, likenum=3000, replynum=null, state='1', parentid='null', articleid='100001'}
    }

    @Test
    public void testFindCommentById() {
        Comment comment = commentService.findCommentById("1");
        System.out.println(comment);
        // Comment{id='1', content='我们不应该把清晨浪费在手机上，健康很重要，一杯温水幸福你我他。', publishtime=null, userid='1002', nickname='相忘于江湖', createdatetime=1970-01-01T08:00, likenum=1000, replynum=null, state='1', parentid='null', articleid='100001'}
    }

    @Test
    public void testSaveComment() {
        Comment comment=new Comment();
        comment.setArticleid("100000");
        comment.setContent("测试添加的数据");
        comment.setCreatedatetime(LocalDateTime.now());
        comment.setUserid("1003");
        comment.setNickname("凯撒大帝");
        comment.setState("1");
        comment.setLikenum(0);
        comment.setReplynum(0);

        commentService.saveComment(comment);

        List<Comment> commentList = commentService.findCommentList();
        for (int i = 0; i < commentList.size(); i++) {
            System.out.println(commentList.get(i));
        }
//        Comment{id='1', content='我们不应该把清晨浪费在手机上，健康很重要，一杯温水幸福你我他。', publishtime=null, userid='1002', nickname='相忘于江湖', createdatetime=1970-01-01T08:00, likenum=1000, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='2', content='我夏天空腹喝凉开水，冬天喝温开水', publishtime=null, userid='1005', nickname='伊人憔悴', createdatetime=1970-01-01T08:00, likenum=888, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='3', content='我一直喝凉开水，冬天夏天都喝。', publishtime=null, userid='1004', nickname='杰克船长', createdatetime=2019-08-06T09:05:06.321, likenum=666, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='4', content='专家说不能空腹吃饭，影响健康。', publishtime=null, userid='1003', nickname='凯撒', createdatetime=2019-08-06T16:18:35.288, likenum=2000, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='5', content='研究表明，刚烧开的水千万不能喝，因为烫嘴。', publishtime=null, userid='1003', nickname='凯撒', createdatetime=2019-08-06T19:01:02.521, likenum=3000, replynum=null, state='1', parentid='null', articleid='100001'}
//        Comment{id='641ba8c8107cbd0910a0e93c', content='测试添加的数据', publishtime=null, userid='1003', nickname='凯撒大帝', createdatetime=2023-03-23T09:18:00.629, likenum=0, replynum=0, state='1', parentid='null', articleid='100000'}

    }
}

6.更新数值字段的值

$inc 方法

更新点赞数

(1) 修改 CommentService

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package com.learn.article.service;

import com.learn.article.dao.CommentRepository;
import com.learn.article.po.Comment;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class CommentService {

    @Autowired
    private CommentRepository commentRepository;

    @Autowired
    private MongoTemplate mongoTemplate;
    
    /**
     * 根据id查询评论
     * @param id
     * @return
     */
    public Comment findCommentById(String id) {
        return commentRepository.findById(id).get();
    }

    /**
     * 点赞数+1
     * @param id
     */
    public void updateCommentLikenum(String id) {
        // 查询对象
        Query query = Query.query(Criteria.where("_id").is(id));
        // 更新对象
        Update update = new Update();
        // 递增 $inc
        update.inc("likenum");

        // 执行更新
        // 参数1：查询对象
        // 参数2：更新对象
        // 参数3：集合的名字或实体类的类型Comment.class
        mongoTemplate.updateFirst(query, update, Comment.class);
    }

}

(2) 添加测试方法

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package com.learn.article.service;

import com.learn.article.ArticleApplication;
import com.learn.article.po.Comment;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.domain.Page;
import org.springframework.test.context.junit4.SpringRunner;

import java.time.LocalDateTime;
import java.util.List;

// SpringBoot的Junit集成测试
@RunWith(SpringRunner.class)
// SpringBoot的测试环境初始化，参数：启动类
@SpringBootTest(classes = ArticleApplication.class)
public class CommentServiceTest {

    @Autowired
    private CommentService commentService;
    
    @Test
    public void testUpdateCommentLikenum() {
        String id = "3";
        Comment commentBefore = commentService.findCommentById(id);
        System.out.println(commentBefore);
        // Comment{id='3', content='我一直喝凉开水，冬天夏天都喝。', publishtime=null, userid='1004', nickname='杰克船长', createdatetime=2019-08-06T09:05:06.321, likenum=666, replynum=null, state='1', parentid='null', articleid='100001'}

        commentService.updateCommentLikenum(id);

        Comment commentAfter = commentService.findCommentById(id);
        System.out.println(commentAfter);
        // Comment{id='3', content='我一直喝凉开水，冬天夏天都喝。', publishtime=null, userid='1004', nickname='杰克船长', createdatetime=2019-08-06T09:05:06.321, likenum=667, replynum=null, state='1', parentid='null', articleid='100001'}
    }
}