在Spring boot中，Mongodb使用聚合框架按计数查找group

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

@Document(collection = "users")
public class User {
    @Id
    private String id;
    private String name;
    private int age;
    // 其他属性和方法
}

@Repository
public interface UserRepository extends MongoRepository<User, String> {
    @Aggregation(pipeline = {
            "{$group: {_id: '$name', count: {$sum: 1}}}",
            "{$sort: {count: -1}}"
    })
    List<UserCount> countUsersByName();
}

public class UserCount {
    private String name;
    private int count;
    // 构造方法、getter和setter方法
}

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public List<UserCount> countUsersByName() {
        return userRepository.countUsersByName();
    }
}