@Component("redisUtils")
@RequiredArgsConstructor
@Slf4j
public class RedisUtils implements InitializingBean {
    private final StringRedisTemplate stringRedisTemplate;
    private static RedisUtils redisUtils;
 
    @Override
    public void afterPropertiesSet() {
        redisUtils = this;
    }
 
    /**
     * 獲取自增ID
     */
    public static <T> Integer getIncr(Class<T> tClass) {
        try {
            String key = tClass.getName();
            Long increment = redisUtils.stringRedisTemplate.opsForValue().increment(key, 1);
            return Math.toIntExact(increment);
        } catch (Exception e) {
            e.printStackTrace();
            throw new RedisSystemException(e.getMessage(), e);
        }
    }
 
    /**
     * 獲取自增ID，指定遞增長度，用于批量創(chuàng)建對象時，只請求一次Redis
     * 如批量創(chuàng)建五個對象，delta等于5
     */
    public static <T> Integer getIncr(Class<T> tClass, int delta) {
        try {
            String key = tClass.getName();
            Long increment = redisUtils.stringRedisTemplate.opsForValue().increment(key, delta);
            return Math.toIntExact(increment);
        } catch (Exception e) {
            e.printStackTrace();
            throw new RedisSystemException(e.getMessage(), e);
        }
    }
 
    /**
     * 緩存預(yù)熱，用于項目啟動時初始化Redis中各個表的最大ID
     */
    public static <T> long incrPreheat(Class<T> tClass, Long maxValue) {
        if (maxValue == null) {
            maxValue = 0L;
        }
        if (maxValue < 0) {
            //異常拋出，預(yù)熱的初始值不能小于0
        }
        Integer incr = getIncr(tClass);
        if (maxValue <= incr) {
            return incr;
        }
        return getIncr(tClass, (int) (maxValue - incr));
    }
}

/**
 * 緩存預(yù)熱
 *
 * @author hxy
 */
@Component
@DependsOn("redisUtils")
@RequiredArgsConstructor
public class RedisInit {
 
    private final UserMapper userMapper;
 
    /**
     * 獲取每一張表中當(dāng)前的最大ID，然后預(yù)熱到redis中
     */
    @PostConstruct
    public void init() {
        RedisUtils.incrPreheat(UserModel.class, userMapper.maxId());
    }
}

@Getter
@Setter
public class UserModel {
 
    private Integer id;
 
    private String name;
 
    private Integer age;
 
    private String tel;
 
    public UserModel() {
    }
 
    /**
     * 提供一個能夠生成自增ID的有參構(gòu)造，需要生成自增ID時調(diào)用
     */
    public UserModel(boolean autoId) {
        if (autoId) {
            this.id = RedisUtils.getIncr(UserModel.class);
        }
    }
}

@Service
@RequiredArgsConstructor
public class UserServiceImpl {
 
    private final UserMapper userMapper;
 
    public void batchAddUser(){
        int addNumber = 10;
        //提前生成自定跨度的ID，比如之前最大ID是6，獲取后得到的incr是16
        Integer incr = RedisUtils.getIncr(UserModel.class, addNumber);
        List<UserModel> userModels = new ArrayList<>();
        for (int i = 0; i < addNumber; i++) {
            UserModel userModel = new UserModel();
            //每一個主鍵ID依次遞減使用
            userModel.setId(incr--);
            userModels.add(userModel);
        }
        userMapper.insertBatch(userModels);
    }
}