1.分页查询

skip+limit形式

mongo中可通过skip+limit来实现文档批量查询的分页逻辑实现，具体javaAPI代码操作如下

  1. @Test
  2. void testSelect() {
  4.     //1.保存测试数据
  5.     for (int i = 1; i <= 10; i++) {
  6.         Student student = new Student();
  7.         student.setId(i);
  8.         student.setName(i + "ftc");
  9.         student.setAge(i);
  10.         mongoTemplate.insert(student);
  11.     }
  13.     //2.验证数据存入
  14.     long count = mongoTemplate.count(new Query(), Student.class);
  15.     Assert.isTrue(10 == count);
  17.     //3.限制条数查询
  18.     Query query = new Query().limit(2);
  19.     List<Student> students = mongoTemplate.find(query, Student.class);
  20.     Assert.isTrue(2 == students.size());
  22.     //4.跳过指定条数查询
  23.     query = new Query().skip(5);
  24.     Student student = mongoTemplate.findOne(query, Student.class);
  25.     Assert.isTrue(6 == student.getAge());
  27.     //5.分页查询
  28.     int pageNum = 4;
  29.     int pageSize = 2;
  30.     query = new Query().skip((pageNum - 1) * pageSize).limit(pageSize);
  31.     students = mongoTemplate.find(query, Student.class);
  32.     Assert.isTrue(7 == students.get(0).getId());
  33.     Assert.isTrue(8 == students.get(1).getId());
  34. }

PageRequest形式

PageRequest类路径：import org.springframework.data.domain.PageRequest;
具体javaAPI如下：

  1. @Test
  2. void testSelect() {
  4.     //1.保存测试数据
  5.     for (int i = 1; i <= 10; i++) {
  6.         Student student = new Student();
  7.         student.setId(i);
  8.         student.setName(i + "ftc");
  9.         student.setAge(i);
  10.         mongoTemplate.insert(student);
  11.     }
  13.     //2.验证数据存入
  14.     long count = mongoTemplate.count(new Query(), Student.class);
  15.     Assert.isTrue(10 == count);
  17.     //3.分页查询
  18.     int pageNum = 4;
  19.     int pageSize = 2;
  21.     PageRequest pageRequest = PageRequest.of(pageNum - 1, pageSize);
  22.     Query query = new Query().with(pageRequest);
  23.     List<Student> students = mongoTemplate.find(query, Student.class);
  24.     Assert.isTrue(7 == students.get(0).getId());
  25.     Assert.isTrue(8 == students.get(1).getId());
  26. }

2.排序

springboot中通过Sort类来指定排序顺序，类路径：import org.springframework.data.domain.Sort;
具体代码如下

  1. @Test
  2. void testSelect() {
  4.     //1.保存测试数据
  5.     for (int i = 1; i <= 10; i++) {
  6.         Student student = new Student();
  7.         student.setId(i);
  8.         student.setName(i + "ftc");
  9.         student.setAge(i);
  10.         mongoTemplate.insert(student);
  11.     }
  13.     //2.验证数据存入
  14.     long count = mongoTemplate.count(new Query(), Student.class);
  15.     Assert.isTrue(10 == count);
  17.     //3.单一排序查询
  18.     Sort sort = Sort.by(Sort.Direction.DESC, "id");
  19.     List<Student> students = mongoTemplate.find(new Query().with(sort), Student.class);
  20.     Assert.isTrue(students.get(0).getAge() == 10);
  21.     Assert.isTrue(students.get(9).getAge() == 1);
  23.     //4.组合排序查询
  24.     sort = Sort.by(Sort.Direction.ASC, "id").and(Sort.by(Sort.Direction.ASC, "age"));
  25.     students = mongoTemplate.find(new Query().with(sort), Student.class);
  26.     Assert.isTrue(students.get(0).getAge() == 1);
  27.     Assert.isTrue(students.get(9).getAge() == 10);
  28. }

3.聚合

springboot中每个聚合管道符都封装了不同的Operation，最终将这些operation整和到一个Aggregation，
最终在查询时，使用Aggregation即可查询
具体javaAPI如下

  1. @Test
  2. void testSelect() {
  4.     //1.保存测试数据
  5.     for (int i = 1; i <= 10; i++) {
  6.         Student student = new Student();
  7.         student.setId(i);
  8.         student.setName(i + "ftc");
  9.         student.setAge(i);
  10.         student.setSex(i % 2 == 0 ? 1 : 0);
  11.         mongoTemplate.insert(student);
  12.     }
  14.     //2.验证数据存入
  15.     long count = mongoTemplate.count(new Query(), Student.class);
  16.     Assert.isTrue(10 == count);
  18.     //3.聚合操作，获取年龄总和
  19.     GroupOperation groupOperation = Aggregation.group().sum("age").as("ageSum");
  20.     TypedAggregation<Student> typedAggregation = Aggregation.newAggregation(Student.class, groupOperation);
  21.     AggregationResults<JSONObject> aggregationResult = mongoTemplate.aggregate(typedAggregation, JSONObject.class);
  22.     JSONObject result = aggregationResult.getUniqueMappedResult();
  23.     Assert.isTrue(55 == result.getInt("ageSum"));
  25.     //4.获取不同性别的人数
  26.     groupOperation = Aggregation.group("sex").count().as("agePeopleSum");
  27.     typedAggregation = Aggregation.newAggregation(Student.class, groupOperation);
  28.     aggregationResult = mongoTemplate.aggregate(typedAggregation, JSONObject.class);
  29.     List<JSONObject> results = aggregationResult.getMappedResults();
  30.     Assert.isTrue(2 == results.size());
  31.     Assert.isTrue(5 == results.get(0).getInt("agePeopleSum"));
  32.     Assert.isTrue(5 == results.get(1).getInt("agePeopleSum"));
  34.     //5.获取年龄平均值
  35.     groupOperation = Aggregation.group().avg("age").as("aveAge");
  36.     typedAggregation = Aggregation.newAggregation(Student.class, groupOperation);
  37.     aggregationResult = mongoTemplate.aggregate(typedAggregation, JSONObject.class);
  38.     result = aggregationResult.getUniqueMappedResult();
  39.     Assert.isTrue(5.5 == result.getDouble("aveAge"));
  41.     //6.计算年龄最大值
  42.     groupOperation = Aggregation.group().max("age").as("maxAge");
  43.     typedAggregation = Aggregation.newAggregation(Student.class, groupOperation);
  44.     aggregationResult = mongoTemplate.aggregate(typedAggregation, JSONObject.class);
  45.     result = aggregationResult.getUniqueMappedResult();
  46.     Assert.isTrue(10 == result.getInt("maxAge"));
  48.     //7.计算年龄大于3的总人数
  49.     MatchOperation matchOperation = Aggregation.match(Criteria.where("age").gt(3));
  50.     groupOperation = Aggregation.group().count().as("peopleSum");
  51.     typedAggregation = Aggregation.newAggregation(Student.class, matchOperation, groupOperation);
  52.     aggregationResult = mongoTemplate.aggregate(typedAggregation, JSONObject.class);
  53.     result = aggregationResult.getUniqueMappedResult();
  54.     Assert.isTrue(7 == result.getInt("peopleSum"));
  55. }

4.联合查询

mongo中虽然提供了lookup进行多表联查，但是个人还是觉得，mongo中能用嵌入式数据结构存储，还是优先使用嵌入式数据结构存储

嵌入式数据模型

  1. 定义学生，成绩实体类。学生属性中嵌套了成绩集合 ```java import lombok.Data; import org.springframework.data.mongodb.core.mapping.Document;

import java.util.List;

/**

  • @author 冯铁城 [17615007230@163.com]
  • @date 2022-07-20 19:12:01
  • @describe: MongoDB实体类

  • “@Document(collection = “student”)” 用于指定对应哪个集合 */ @Data @Document(collection = “student”) public class Student {

    private long id;

    private String name;

    private int age;

    /**

    • 性别 1-男 0-女 */ private int sex;

      private List grades; } java import lombok.Data;

/**

  • @author 冯铁城 [17615007230@163.com]
  • @date 2022-07-25 18:26:51

  • @describe: */ @Data public class Grade {

    private String name;

    private Double score; } ```

  1. 直接查询即可获取到嵌套的成绩集合

    1. @Test
    2. void testSelect() {
    4.  //1.定义成绩集合
    5.  List<Grade> grades = CollUtil.newArrayList();
    6.  Grade grade = new Grade();
    7.  grade.setName("语文");
    8.  grade.setScore(77.7);
    9.  grades.add(grade);
    11.  grade = new Grade();
    12.  grade.setName("数学");
    13.  grade.setScore(66.8);
    14.  grades.add(grade);
    16.  grade = new Grade();
    17.  grade.setName("英语");
    18.  grade.setScore(99.3);
    19.  grades.add(grade);
    21.  //2.定义学生
    22.  Student student = new Student();
    23.  student.setAge(18);
    24.  student.setSex(1);
    25.  student.setName("冯铁城");
    26.  student.setGrades(grades);
    28.  //3.存储
    29.  mongoTemplate.insert(student);
    30.  Student result = mongoTemplate.findOne(new Query(), Student.class);
    31.  Assert.isTrue(result.getAge() == student.getAge());
    32.  Assert.isTrue(result.getName().equals(student.getName()));
    33.  Assert.isTrue(result.getSex() == student.getSex());
    34.  Assert.isTrue(JSONUtil.toJsonStr(result.getGrades()).equals(JSONUtil.toJsonStr(student.getGrades())));
    35. }

    引用式数据模型

    使用unwind管道符

    使用unwind会将指定的聚合数组字段拆分为多条数据

  2. 定义成绩类，对应成绩文档 ```java import lombok.Data; import org.springframework.data.mongodb.core.mapping.Document;

/**

  • @author 冯铁城 [17615007230@163.com]
  • @date 2022-07-25 18:26:51

  • @describe: */ @Data @Document(collection = “grade”) public class Grade {

    private String id;

    private String studentId;

    private String name;

    private Double score; } ```

  1. 定义学生类，对应学生文档 ```java import lombok.Data; import org.springframework.data.mongodb.core.mapping.Document;

/**

  • @author 冯铁城 [17615007230@163.com]
  • @date 2022-07-20 19:12:01
  • @describe: MongoDB实体类

  • “@Document(collection = “student”)” 用于指定对应哪个集合 */ @Data @Document(collection = “student”) public class Student {

    private String id;

    private String name;

    private int age;

    /**

    • 性别 1-男 0-女 */ private int sex;

      private Grade grade; } ```

  1. 使用lookup进行查询

    1. @Test
    2. void testSelect() {
    4.  //1.定义学生
    5.  Student student = new Student();
    6.  student.setAge(18);
    7.  student.setSex(1);
    8.  student.setName("冯铁城");
    9.  student = mongoTemplate.insert(student);
    11.  //2.定义成绩
    12.  List<Grade> grades = CollUtil.newArrayList();
    13.  Grade grade = new Grade();
    14.  grade.setName("语文");
    15.  grade.setScore(77.7);
    16.  grade.setStudentId(student.getId());
    17.  grades.add(grade);
    19.  grade = new Grade();
    20.  grade.setName("数学");
    21.  grade.setScore(66.8);
    22.  grade.setStudentId(student.getId());
    23.  grades.add(grade);
    25.  grade = new Grade();
    26.  grade.setName("英语");
    27.  grade.setScore(99.3);
    28.  grade.setStudentId(student.getId());
    29.  grades.add(grade);
    30.  mongoTemplate.insert(grades, Grade.class);
    32.  //3.定义lookup、unwind管道符
    33.  LookupOperation lookupOperation = Aggregation.lookup("grade", "id", "student_id", "grade");
    34.  UnwindOperation unwindOperation = Aggregation.unwind("grade");
    35.  TypedAggregation<Student> typedAggregation = Aggregation.newAggregation(Student.class, lookupOperation, unwindOperation);
    37.  //4.查询
    38.  AggregationResults<Student> aggregate = mongoTemplate.aggregate(typedAggregation, Student.class);
    39.  List<Student> students = aggregate.getMappedResults();
    40.  Console.log(JSONUtil.toJsonPrettyStr(students));
    41. }

  2. 验证

控制台输入如图，多表联查成功

image.png
不使用unwind管道符

  1. 定义成绩类，对应成绩文档（与使用unwind一致，不做过多累述）
  2. 定义学生类，对应学生文档 ```java import lombok.Data; import org.springframework.data.mongodb.core.mapping.Document;

import java.util.List;

/**

  • @author 冯铁城 [17615007230@163.com]
  • @date 2022-07-20 19:12:01
  • @describe: MongoDB实体类

  • “@Document(collection = “student”)” 用于指定对应哪个集合 */ @Data @Document(collection = “student”) public class Student {

    private String id;

    private String name;

    private int age;

    /**

    • 性别 1-男 0-女 */ private int sex;

      private List grades; } ```

  1. 使用lookup进行查询

    1. @Test
    2. void testSelect() {
    4.  //1.定义学生
    5.  Student student = new Student();
    6.  student.setAge(18);
    7.  student.setSex(1);
    8.  student.setName("冯铁城");
    9.  student = mongoTemplate.insert(student);
    11.  //2.定义成绩
    12.  List<Grade> grades = CollUtil.newArrayList();
    13.  Grade grade = new Grade();
    14.  grade.setName("语文");
    15.  grade.setScore(77.7);
    16.  grade.setStudentId(student.getId());
    17.  grades.add(grade);
    19.  grade = new Grade();
    20.  grade.setName("数学");
    21.  grade.setScore(66.8);
    22.  grade.setStudentId(student.getId());
    23.  grades.add(grade);
    25.  grade = new Grade();
    26.  grade.setName("英语");
    27.  grade.setScore(99.3);
    28.  grade.setStudentId(student.getId());
    29.  grades.add(grade);
    30.  mongoTemplate.insert(grades, Grade.class);
    32.  //3.定义lookup、unwind管道符
    33.  LookupOperation lookupOperation = Aggregation.lookup("grade", "id", "student_id", "grades");
    34.  TypedAggregation<Student> typedAggregation = Aggregation.newAggregation(Student.class, lookupOperation);
    36.  //4.查询
    37.  AggregationResults<Student> aggregate = mongoTemplate.aggregate(typedAggregation, Student.class);
    38.  Student result = aggregate.getUniqueMappedResult();
    39.  Console.log(JSONUtil.toJsonPrettyStr(result));
    40. }

  2. 验证

控制台输入如图，多表联查成功
image.png