Mybatis-Plus在插入数据后获得自增主键ID

问题：继承BaseMapeer采用自带的insert之后，返回的是插入成功的条数，无法获得自增主键的ID

=======MAPPER=======
@Mapper
@Repository
public interface StudentMapper extends BaseMapper<Student> {
}

====Entity=========
public class Student {

    private Integer id;

    private String name;

    private Integer age;
    
}
=======Service=======
@Service
public class StudentServiceImpl implements StudentService {

@Override
public int saveStudent(Student student) {
    return studentMapper.insert(student);
}
}

 改用save方法

首先在实体类设置自增主键、然后extends

=======MAPPER=======
@Mapper
@Repository
public interface StudentMapper extends BaseMapper<Student> {
}

====Entity=========
public class Student {

    @TableId(type = IdType.AUTO)
    private Integer id;

    private String name;

    private Integer age;
    
}
=======Service=======
@Service
public class StudentServiceImpl extends ServiceImpl<StudentMapper,Student> implements StudentService {

@Override
public int saveStudent(Student student) {
    boolean res = save(student);
    if(!res){log.error("插入失败");
    //此时getId就能拿到主键了
    Integer sid = student.getId();
    return student;
}
}