一、创建集合与索引 / 引入依赖 / 写入配置

1.mongo客户端

db.comment.insertMany([
    { "commentid" : "1", "state" : 1, "parentid" : "0", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "哈哈", "nickname" : "梨花带雨", "likenum" : 16, "unlikenum" : 7, "replynum" : 0 },
    { "commentid" : "2", "state" : 1, "parentid" : "0", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "什么", "nickname" : "杏花带雨", "likenum" : 56, "unlikenum" : 7, "replynum" : 0 },
    { "commentid" : "3", "state" : 1, "parentid" : "0", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "bajc", "nickname" : "海棠带雨", "likenum" : 56, "unlikenum" : 7, "replynum" : 0 },
    { "commentid" : "4", "state" : 1, "parentid" : "0", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "cdbica", "nickname" : "迎春花带雨", "likenum" : 56, "unlikenum" : 7, "replynum" : 2 },
    { "commentid" : "5", "state" : 1, "parentid" : "4", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "r", "nickname" : "玫瑰花带雨", "likenum" : 56, "unlikenum" : 7, "replynum" : 0 },
    { "commentid" : "6", "state" : 1, "parentid" : "4", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "bciadc", "nickname" : "满天星带雨", "likenum" : 56, "unlikenum" : 7, "replynum" : 1 },
    { "commentid" : "7", "state" : 1, "parentid" : "5", "userid" : 17, "publishtime" : ISODate("2022-05-13T01:41:17.816Z"), "comment" : "ocasoaiji", "nickname" : "桃花带雨", "likenum" : 56, "unlikenum" : 0, "replynum" : 0 },
    { "commentid" : "8", "state" : 1, "parentid" : "0", "comment" : "我看你", "publishtime" : ISODate("2022-05-13T04:45:49.616Z"), "userid" : 17, "nickname" : "mup", "likenum" : 8, "unlikenum" : 0, "replynum" : 0 }
])
db.comment.createIndex({commentid:1},{unique:true})

 

2.pom.xml

    　　<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-mongodb -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
            <version>2.3.0.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-test -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>2.3.0.RELEASE</version>
            <scope>test</scope>
        </dependency>

3.application-dev.yml

#开发环境
spring:
  #mongodb
  data:
    mongodb:
      host: 127.0.0.1
      database: comments
      port: 27017

二、Java代码demo

1.Comment 实体类

  1 package com.miaoshaproject.comment.pojo;
  2 
  3 import org.springframework.data.annotation.Id;
  4 import org.springframework.data.mongodb.core.index.CompoundIndex;
  5 import org.springframework.data.mongodb.core.index.CompoundIndexes;
  6 import org.springframework.data.mongodb.core.index.Indexed;
  7 import org.springframework.data.mongodb.core.mapping.Document;
  8 
  9 import java.io.Serializable;
 10 import java.util.Date;
 11 
 12 /**
 13  * @Author wangshuo
 14  * @Date 2022/5/12, 21:43
 15  * Please add a comment
 16  */
 17 @Document(collection = "comment")//绑定mongodb集合
 18 //@CompoundIndex(def = "{'commentid':1,'comment':-1}")：添加复合索引，索引建议用小黑窗创建
 19 public class Comment implements Serializable {
 20 
 21     //主键id
 22     @Id
 23     private String id;
 24 
 25     //评论id
 26     private String commentid;
 27 
 28     //评论内容
 29     //@Field("comment")： 对应的mongodb字段名，若这里的命名与mongodb的名字一样就不需要加这个注解了
 30     private String comment;
 31 
 32     //发布日期
 33     private Date publishtime;
 34 
 35     //添加单列索引
 36     @Indexed
 37     private Integer userid;
 38 
 39     //用户昵称
 40     private String nickname;
 41 
 42     private Integer likenum;
 43 
 44     private Integer unlikenum;
 45 
 46     //回复数
 47     private Integer replynum;
 48 
 49     //状态：1.评论正常 2.评论违规被折叠 3.已删除
 50     private Integer state;
 51 
 52     //子评论属性：上一级id
 53     private String parentid;
 54 
 55     public String getId() {
 56         return id;
 57     }
 58 
 59     public void setId(String id) {
 60         this.id = id;
 61     }
 62 
 63     @Override
 64     public String toString() {
 65         return "Comment{" +
 66                 "commentid='" + commentid + '\'' +
 67                 ", comment='" + comment + '\'' +
 68                 ", publishtime=" + publishtime +
 69                 ", userid=" + userid +
 70                 ", nickname='" + nickname + '\'' +
 71                 ", likenum=" + likenum +
 72                 ", unlikenum=" + unlikenum +
 73                 ", replynum=" + replynum +
 74                 ", state='" + state + '\'' +
 75                 ", parentid='" + parentid + '\'' +
 76                 '}';
 77     }
 78 
 79     public String getCommentid() {
 80         return commentid;
 81     }
 82 
 83     public void setCommentid(String commentid) {
 84         this.commentid = commentid;
 85     }
 86 
 87     public String getComment() {
 88         return comment;
 89     }
 90 
 91     public void setComment(String comment) {
 92         this.comment = comment;
 93     }
 94 
 95     public Date getPublishtime() {
 96         return publishtime;
 97     }
 98 
 99     public void setPublishtime(Date publishtime) {
100         this.publishtime = publishtime;
101     }
102 
103     public Integer getUserid() {
104         return userid;
105     }
106 
107     public void setUserid(Integer userid) {
108         this.userid = userid;
109     }
110 
111     public String getNickname() {
112         return nickname;
113     }
114 
115     public void setNickname(String nickname) {
116         this.nickname = nickname;
117     }
118 
119     public Integer getLikenum() {
120         return likenum;
121     }
122 
123     public void setLikenum(Integer likenum) {
124         this.likenum = likenum;
125     }
126 
127     public Integer getUnlikenum() {
128         return unlikenum;
129     }
130 
131     public void setUnlikenum(Integer unlikenum) {
132         this.unlikenum = unlikenum;
133     }
134 
135     public Integer getReplynum() {
136         return replynum;
137     }
138 
139     public void setReplynum(Integer replynum) {
140         this.replynum = replynum;
141     }
142 
143     public Integer getState() {
144         return state;
145     }
146 
147     public void setState(Integer state) {
148         this.state = state;
149     }
150 
151     public String getParentid() {
152         return parentid;
153     }
154 
155     public void setParentid(String parentid) {
156         this.parentid = parentid;
157     }
158 }

2.CommentRepository dao层接口，继承MongoRepository

 1 package com.miaoshaproject.comment.dao;
 2 
 3 import com.miaoshaproject.comment.pojo.Comment;
 4 import org.springframework.data.domain.Page;
 5 import org.springframework.data.domain.PageRequest;
 6 import org.springframework.data.mongodb.repository.MongoRepository;
 7 import org.springframework.data.mongodb.repository.Query;
 8 
 9 import java.util.List;
10 
11 /**
12  * @Author wangshuo
13  * @Date 2022/5/13, 8:47
14  * 继承MongoRepository,绑定集合
15  */
16 public interface CommentRepository extends MongoRepository<Comment, String> {
17 
18     //方法名不要写错，第二个参数用于分页
19     Page<Comment> findByParentid(String parentid, PageRequest pageable);
20 
21     //使用@Query的原生查询语句的方式查询
22     //使用这种方式方法名可以自定义
23     @Query(value = "{ parentid: ?0 }" ,sort = "{publishtime : -1}")
24     List<Comment> selectSortPagingDataByParentId(String parentid);
25 }

 

3.CommentService

 1 package com.miaoshaproject.comment.service;
 2 
 3 import com.miaoshaproject.comment.dao.CommentRepository;
 4 import com.miaoshaproject.comment.pojo.Comment;
 5 import org.springframework.beans.factory.annotation.Autowired;
 6 import org.springframework.data.domain.Page;
 7 import org.springframework.data.domain.PageRequest;
 8 import org.springframework.data.mongodb.core.MongoTemplate;
 9 import org.springframework.data.mongodb.core.query.Criteria;
10 import org.springframework.data.mongodb.core.query.Query;
11 import org.springframework.data.mongodb.core.query.Update;
12 import org.springframework.stereotype.Service;
13 
14 import java.util.List;
15 
16 /**
17  * @Author wangshuo
18  * @Date 2022/5/13, 8:49
19  * Please add a comment
20  */
21 @Service
22 public class CommentService {
23 
24     @Autowired
25     CommentRepository commentRepository;
26     @Autowired
27     MongoTemplate mongoTemplate;
28 
29     public void saveComment(Comment comment) {
30         commentRepository.save(comment);
31     }
32 
33     public void updateComment(Comment comment) {
34         commentRepository.save(comment);
35     }
36 
37     public List<Comment> findCommentList() {
38         return commentRepository.findAll();
39     }
40 
41     public Comment findCommentById(String id) {
42         return commentRepository.findById(id).get();
43     }
44 
45     public void deleteCommentById(String id) {
46         commentRepository.deleteById(id);
47     }
48 
49     public Page<Comment> findByParentId(String parentid, int page, int size) {
50 
51         //需要注意默认page是从0开始的，为了更易于应用，我们在这里直接给他减一，这样我们查询第一页的时候就可以直接传入参数1
52         Page<Comment> byParentid = commentRepository.findByParentid(parentid, PageRequest.of(page - 1, size));
53         return byParentid;
54     }
55 
56     //使用MongoTemplate来进行操作，好处是在一些情境下可以减少IO操作
57     public void incrCommentLikeNum(String id) {
58 
59         //参数1 查询条件 可以一直and
60         Query query = Query.query(Criteria.where("commentid").is(id))/*.addCriteria()*/;
61         //参数2 更新条件
62         Update update = new Update();
63         update.inc("likenum");
64         //.updateFirst 修改一条 .updateMulti 修改多条
65         mongoTemplate.updateFirst(query, update, Comment.class);
66     }
67 
68     public List<Comment> selectSortPagingDataByParentId(String parentid) {
69         return commentRepository.selectSortPagingDataByParentId(parentid);
70     }
71 }

 

三、单元测试代码是否正常

  • CommentServiceTest

  1 package com.miaoshaproject;
  2 
  3 import com.miaoshaproject.comment.pojo.Comment;
  4 import com.miaoshaproject.comment.service.CommentService;
  5 import com.miaoshaproject.demo.SnowFlakeID;
  6 import com.miaoshaproject.service.impl.OrderServiceImpl;
  7 import org.junit.Test;
  8 import org.junit.runner.RunWith;
  9 import org.springframework.beans.factory.annotation.Autowired;
 10 import org.springframework.boot.test.context.SpringBootTest;
 11 import org.springframework.data.domain.Page;
 12 import org.springframework.test.context.junit4.SpringRunner;
 13 
 14 import javax.annotation.Resource;
 15 import java.util.Date;
 16 import java.util.List;
 17 
 18 /**
 19  * @Author wangshuo
 20  * @Date 2022/5/13, 9:42
 21  * 依赖于spring-boot-starter-test的Test
 22  */
 23 @RunWith(SpringRunner.class)
 24 @SpringBootTest
 25 public class CommentServiceTest {
 26 
 27     @Autowired
 28     CommentService commentService;
 29     @Autowired
 30     OrderServiceImpl orderService;
 31 
 32     @Test
 33     public void testFindCommentList() {
 34 
 35         List<Comment> commentList = commentService.findCommentList();
 36         for (Comment comment : commentList) {
 37             System.out.println(comment);
 38         }
 39     }
 40 
 41     @Test
 42     public void testSaveComment(){
 43 
 44         Comment comment = new Comment();
 45         comment.setComment("我看你");
 46         //自定义算法生成
 47         //comment.setCommentid(orderService.generateOrderNO());
 48         //基于雪花算法生成
 49         SnowFlakeID idWorker = new SnowFlakeID(0, 0);
 50         String s = String.valueOf(idWorker.nextId());
 51         System.out.println(s);
 52         comment.setCommentid(s);
 53         comment.setLikenum(8);
 54         comment.setNickname("mup");
 55         //父级ID
 56         comment.setParentid("0");
 57         comment.setPublishtime(new Date());
 58         comment.setReplynum(0);
 59         comment.setState(1);
 60         comment.setUserid(17);
 61         comment.setUnlikenum(0);
 62         commentService.saveComment(comment);
 63     }
 64 
 65     //条件查询和分页：查询根据子评论ID查询父评论详情
 66     @Test
 67     public void testFindByParentId(){
 68 
 69         Page<Comment> page = commentService.findByParentId("4", 1, 5);
 70         System.out.println(page.getTotalElements());
 71         for (Comment comment : page.getContent()) {
 72             System.out.println(comment);
 73         }
 74     }
 75 
 76     //根据ID 喜欢数加一
 77     @Test
 78     public void testIncrCommentLikeNum(){
 79 
 80         commentService.incrCommentLikeNum("974733071427305472");
 81     }
 82 
 83     /*
 84         关于@Query分页：
 85             问题: 在互联网发展的今天，大部分数据的体量都是庞大的，跳页的需求将消耗更多的内存和cpu，对应的就是查询慢。
 86         当然，如果数量不大，如果不介意慢一点，那么skip也不是啥问题，关键要看业务场景。
 87         看起来，分页已经实现了，但是官方文档并不推荐，说会扫描全部文档，然后再返回结果。
 88         The cursor.skip() method requires the server to scan from the beginning of the input results set before beginning to return results. As the offset increases, cursor.skip() will become slower.
 89         所以，需要一种更快的方式。其实和mysql数量大之后不推荐用limit m,n一样，解决方案是先查出当前页的第一条，然后顺序数pageSize条。MongoDB官方也是这样推荐的。
 90             来看看大厂们怎么做的
 91         Google最常用了，看起来是有跳页选择的啊。再仔细看，只有10页，多的就必须下一页，并没有提供一共多少页，跳到任意页的选择。这不就是我们的find-condition-then-limit方案吗，只是他的一页数量比较多，前端或者后端把这一页给切成了10份。
 92         同样，看Facebook，虽然提供了总count，但也只能下一页。
 93         其他场景，比如Twitter，微博，朋友圈等，根本没有跳页的概念的。
 94      */
 95 
 96     @Test
 97     public void selectSortPagingDataByParentId(){
 98 
 99         List<Comment> comments = commentService.selectSortPagingDataByParentId("4");
100         for (Comment comment : comments) {
101             System.out.println(comment);
102         }
103     }
104 }