//通用的方法-记录用户秒杀成功后生成的订单-并进行异步邮件消息的通知
private void commonRecordKillSuccessInfo(ItemKill kill, Integer userId) throws Exception{//TODO:记录抢购成功后生成的秒杀订单记录
 ItemKillSuccess entity=new ItemKillSuccess();//此处为订单编号的生成逻辑String orderNo=String.valueOf(snowFlake.nextId());//entity.setCode(RandomUtil.generateOrderCode());   //传统时间戳+N位随机数entity.setCode(orderNo); //雪花算法
 entity.setItemId(kill.getItemId());entity.setKillId(kill.getId());entity.setUserId(userId.toString());entity.setStatus(SysConstant.OrderStatus.SuccessNotPayed.getCode().byteValue());entity.setCreateTime(DateTime.now().toDate());//TODO:学以致用，举一反三 -> 仿照单例模式的双重检验锁写法if (itemKillSuccessMapper.countByKillUserId(kill.getId(),userId) <= 0){int res=itemKillSuccessMapper.insertSelective(entity);//其他逻辑省略
    }
}

CREATE TABLE `random_code` (`id` int(11) NOT NULL AUTO_INCREMENT,`code` varchar(255) DEFAULT NULL,PRIMARY KEY (`id`),UNIQUE KEY `idx_code` (`code`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*** 随机数生成的方式-Thread* @Author:debug (SteadyJack)* @Date: 2019/7/11 10:30**/
public class CodeGenerateThread implements Runnable{private RandomCodeMapper randomCodeMapper;public CodeGenerateThread(RandomCodeMapper randomCodeMapper) {this.randomCodeMapper = randomCodeMapper;}@Override
public void run() {//生成订单编号并插入数据库RandomCode entity=new RandomCode();entity.setCode(RandomUtil.generateOrderCode());randomCodeMapper.insertSelective(entity);}
}

/*** 随机数生成util* @Author:debug (SteadyJack)* @Date: 2019/6/20 21:05**/
public class RandomUtil {private static final SimpleDateFormat dateFormatOne=new SimpleDateFormat("yyyyMMddHHmmssSS");private static final ThreadLocalRandom random=ThreadLocalRandom.current();//生成订单编号-方式一public static String generateOrderCode(){//TODO:时间戳+N为随机数流水号return dateFormatOne.format(DateTime.now().toDate()) + generateNumber(4);}//N为随机数流水号public static String generateNumber(final int num){StringBuffer sb=new StringBuffer();for (int i=1;i<=num;i++){sb.append(random.nextInt(9));}return sb.toString();}
}

@Autowired
private RandomCodeMapper randomCodeMapper;//测试在高并发下多线程生成订单编号-传统的随机数生成方法
@RequestMapping(value = "/code/generate/thread",method = RequestMethod.GET)
public BaseResponse codeThread(){BaseResponse response=new BaseResponse(StatusCode.Success);try {ExecutorService executorService=Executors.newFixedThreadPool(10);for (int i=0;i<1000;i++){executorService.execute(new CodeGenerateThread(randomCodeMapper));}}catch (Exception e){response=new BaseResponse(StatusCode.Fail.getCode(),e.getMessage());}return response;
}

/** 基于雪花算法生成全局唯一的订单编号并插入数据库表中* @Author:debug (SteadyJack)* @Date: 2019/7/11 10:30**/
public class CodeGenerateSnowThread implements Runnable{private static final SnowFlake SNOW_FLAKE=new SnowFlake(2,3);private RandomCodeMapper randomCodeMapper;public CodeGenerateSnowThread(RandomCodeMapper randomCodeMapper) {this.randomCodeMapper = randomCodeMapper;}@Overridepublic void run() {RandomCode entity=new RandomCode();//采用雪花算法生成订单编号
        entity.setCode(String.valueOf(SNOW_FLAKE.nextId()));randomCodeMapper.insertSelective(entity);}
}

/** * 雪花算法* @author: zhonglinsen* @date: 2019/5/20*/
public class SnowFlake {//起始的时间戳private final static long START_STAMP = 1480166465631L;//每一部分占用的位数private final static long SEQUENCE_BIT = 12; //序列号占用的位数private final static long MACHINE_BIT = 5;   //机器标识占用的位数private final static long DATA_CENTER_BIT = 5;//数据中心占用的位数//每一部分的最大值private final static long MAX_DATA_CENTER_NUM = -1L ^ (-1L << DATA_CENTER_BIT);private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);//每一部分向左的位移private final static long MACHINE_LEFT = SEQUENCE_BIT;private final static long DATA_CENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;private final static long TIMESTAMP_LEFT = DATA_CENTER_LEFT + DATA_CENTER_BIT;private long dataCenterId;  //数据中心private long machineId;     //机器标识private long sequence = 0L; //序列号private long lastStamp = -1L;//上一次时间戳public SnowFlake(long dataCenterId, long machineId) {if (dataCenterId > MAX_DATA_CENTER_NUM || dataCenterId < 0) {throw new IllegalArgumentException("dataCenterId can't be greater than MAX_DATA_CENTER_NUM or less than 0");}if (machineId > MAX_MACHINE_NUM || machineId < 0) {throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");}this.dataCenterId = dataCenterId;this.machineId = machineId;}//产生下一个IDpublic synchronized long nextId() {long currStamp = getNewStamp();if (currStamp < lastStamp) {throw new RuntimeException("Clock moved backwards.  Refusing to generate id");}if (currStamp == lastStamp) {//相同毫秒内，序列号自增sequence = (sequence + 1) & MAX_SEQUENCE;//同一毫秒的序列数已经达到最大if (sequence == 0L) {currStamp = getNextMill();}} else {//不同毫秒内，序列号置为0sequence = 0L;}lastStamp = currStamp;return (currStamp - START_STAMP) << TIMESTAMP_LEFT //时间戳部分| dataCenterId << DATA_CENTER_LEFT       //数据中心部分| machineId << MACHINE_LEFT             //机器标识部分| sequence;                             //序列号部分
    }private long getNextMill() {long mill = getNewStamp();while (mill <= lastStamp) {mill = getNewStamp();}return mill;}private long getNewStamp() {return System.currentTimeMillis();}
}

/*** 测试在高并发下多线程生成订单编号-雪花算法* @return*/
@RequestMapping(value = "/code/generate/thread/snow",method = RequestMethod.GET)
public BaseResponse codeThreadSnowFlake(){BaseResponse response=new BaseResponse(StatusCode.Success);try {ExecutorService executorService=Executors.newFixedThreadPool(10);for (int i=0;i<1000;i++){executorService.execute(new CodeGenerateSnowThread(randomCodeMapper));}}catch (Exception e){response=new BaseResponse(StatusCode.Fail.getCode(),e.getMessage());}return response;
}

ItemKillSuccess entity=new ItemKillSuccess();
String orderNo=String.valueOf(snowFlake.nextId());//雪花算法
entity.setCode(orderNo);
//其他代码省略