### Question:
UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { @DS("master") @Override public void addUser(User user) { baseMapper.insert(user); }  @DS("master") @Override void addUser(User user);  }### Answer:
@Test public void addUser() { User userMaster = User.builder().name("主库添加").age(20).build(); userService.addUser(userMaster); User userSlave = User.builder().name("从库添加").age(20).build(); userService.save(userSlave); }