#  application.yml
# DataSource Config
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/test
    username: root
    password: 123456
#    type: com.alibaba.druid.pool.DruidDataSource

mybatis-flex:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

@Data
@Table("t_role")
public class Role implements Serializable {
    @Id(keyType = KeyType.Auto)
    private Integer id;

    private String name;

    @RelationManyToMany(
            joinTable = "t_user_role",
            joinSelfColumn = "role_id",
            joinTargetColumn = "user_id")
    private List<User> users;
}

@Data
@Table("t_user")
public class User implements Serializable {

    @Id(keyType = KeyType.Auto)
    private Integer id;

    private String name;

    @RelationManyToMany(
            joinTable = "t_user_role",
            joinSelfColumn = "user_id",
            joinTargetColumn = "role_id")
    private List<Role> roles;
}

CREATE TABLE `t_role` (
  `id` int NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
CREATE TABLE `t_user` (
  `id` int NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
CREATE TABLE `t_user_role` (
  `role_id` int DEFAULT NULL,
  `user_id` int DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

@SpringBootTest
public class StudentTest {
    @Autowired
    UserMapper userMapper;
    @Autowired
    RoleMapper roleMapper;

 
    @Test
    public void get (){
        List<Role> roles = userMapper.selectOneWithRelationsById(2).getRoles();
        List<User> users = roleMapper.selectOneWithRelationsById(2).getUsers();
        System.out.println(roles.size());
        System.out.println(users.size());
    }
}

Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2cd3fc29] was not registered for synchronization because synchronization is not active
2023-08-29 13:57:47.107  INFO 16112 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2023-08-29 13:57:47.336  INFO 16112 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Added connection com.mysql.cj.jdbc.ConnectionImpl@669c2b07
2023-08-29 13:57:47.338  INFO 16112 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
==>  Preparing: SELECT * FROM `t_user` WHERE `id` = ?
==> Parameters: 2(Integer)
<==    Columns: id, name, username, password, sex, phone, code, address
<==        Row: 2, 2, 2, 2, 2, 2, 2, 2
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2cd3fc29]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6475e778] was not registered for synchronization because synchronization is not active
==>  Preparing: SELECT * FROM `t_user_role` WHERE user_id = ?
==> Parameters: 2(Integer)
<==    Columns: role_id, user_id
<==        Row: 1, 2
<==        Row: 2, 2
<==      Total: 2
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6475e778]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@fd5689d] was not registered for synchronization because synchronization is not active
==>  Preparing: SELECT * FROM `t_role` WHERE `id` = ?
==> Parameters: 2(Integer)
<==    Columns: id, name
<==        Row: 2, 2
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@fd5689d]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@218f2f51] was not registered for synchronization because synchronization is not active
==>  Preparing: SELECT * FROM `t_user_role` WHERE role_id = ?
==> Parameters: 2(Integer)
<==    Columns: role_id, user_id
<==        Row: 2, 1
<==        Row: 2, 2
<==      Total: 2
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@218f2f51]
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