生成随机单据号

背景：全局生成4位字符2222-9ZZ9

实现方式：

使用redis的原子自增 + google的retry保证，生成4位数

1、pom

<dependency><groupId>com.github.rholder</groupId><artifactId>guava-retrying</artifactId><version>2.0.0</version>
</dependency>

2、获取单号序列重试器

private final Retryer<Long> getOrderSequenceRetryer = RetryerBuilder.<Long>newBuilder().retryIfResult(Objects::isNull).retryIfException().withWaitStrategy(WaitStrategies.incrementingWait(30, TimeUnit.MILLISECONDS, 10, TimeUnit.MILLISECONDS)).withStopStrategy(StopStrategies.stopAfterAttempt(2)).build();

3、redis原子自增 + guava的重试机制保证

private String getFallbackSuffix() {Long num;try {num = getOrderSequenceRetryer.call(() -> redisGateway.incr()//使用redis的原子自增+1，并设置过期时间);} catch (Exception e) {throw new RuntimeException("redis incr exception", e);}return getSuffix(num.intValue());}

4、将生成的原子自增数，取后缀，最终4位范围【2222-9ZZ9】和业务相关

     /*** 获取后缀* [(2-9), (2-9,A-H,J-N,P-Z), 2-9,A-H,J-N,P-Z), (2-9)]* 2222-9ZZ9** @param num num* @return suffix*/public static String getSuffix(int num) {String[] suffixFactors = new String[]{"2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F","G", "H", "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};// 65536 = 8 * 32 * 32 * 8int serialNumberThreshold = 65536;if (num >= 0 && num < serialNumberThreshold) {int index4 = num / 8192;int mod4 = num % 8192;int index3 = mod4 / 256;int mod3 = mod4 % 256;int index2 = mod3 / 8;int mod2 = mod3 % 8;return suffixFactors[index4] + suffixFactors[index3] + suffixFactors[index2] + suffixFactors[mod2];}throw new IllegalArgumentException("num 超过流水号阈值,单号可能会重复!!!");}

注意事项

1、单据号中，最好不要说使用1和l，0和o（数字只能用8个，字母只能用大写的24个）

2、guava的重试机制参考：

https://zzzgd.blog.csdn.net/article/details/84377962?spm=1001.2101.3001.6650.1&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1.pc_relevant_default&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1.pc_relevant_default&utm_relevant_index=2

UUID

public class IdUtil {/** 返回使用ThreadLocalRandom的UUID，比默认的UUID性能更优*/public static UUID fastUUID() {ThreadLocalRandom random = ThreadLocalRandom.current();return new UUID(random.nextLong(), random.nextLong());}
}

随机生成前缀 + 日期 + 后缀随机5位数

    private static final DateTimeFormatter FORMATTER_DATE_YYYYMMDDHHMMSS = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");@Testpublic void t() throws Exception {String suffix = StringUtils.leftPad(String.valueOf(new Random().nextInt(100)), 5, "0");String result = "prefix" + formatLocalDateTime(LocalDateTime.now()) + suffix;}public static String formatLocalDateTime(LocalDateTime localDateTime) {return FORMATTER_DATE_YYYYMMDDHHMMSS.format(localDateTime);}