ID的组成部分:
- 符号位:1bit,永远为0
- 时间戳:31bit,以秒为单位,可以使用69年
- 序列号:32bit,秒内的计数器,支持每秒产生2^32个不同ID
生成代码:
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public class RedisIdWorker { /** * 开始时间戳 */ private static final long BEGIN_TIMESTAMP = 1640995200L; /** * 序列号的位数 */ private static final int COUNT_BITS = 32 ; private StringRedisTemplate stringRedisTemplate; //构造方法形式注入 public RedisIdWorker(StringRedisTemplate stringRedisTemplate) { this .stringRedisTemplate = stringRedisTemplate; } public long nextId(String keyPrefix){ //1. 生成时间戳 LocalDateTime now = LocalDateTime.now(); long nowSecond = now.toEpochSecond(ZoneOffset.UTC); long timestamp = nowSecond - BEGIN_TIMESTAMP; //2.生成序列号 // 2.1 获取当前日期,精确到天 String date = now.format(DateTimeFormatter.ofPattern( "yyyy:MM:dd" )); long count = stringRedisTemplate.opsForValue().increment( "icr:" + keyPrefix + ":" + date); //3.拼接并返回 return timestamp << COUNT_BITS | count; } } |
PS:Redis实现全局唯一id生成
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import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.core.RedisTemplate; import org.springframework.stereotype.Component; import org.springframework.util.Assert; import java.time.LocalDate; import java.time.format.DateTimeFormatter; import java.util.Calendar; import java.util.concurrent.TimeUnit; /** * 描述: * 唯一ID生成器 * @author jimmy * @create 2020-11-06 16:06 */ @Component public class GenerateIDUtil { @Autowired private RedisTemplate redisTemplate; /** * 生成每天的初始Id * @param key * @return */ public String initPrimaryId(String key) { Assert.hasLength(key, "hashName不能为空" ); String hashCol = LocalDate.now().format(DateTimeFormatter.ofPattern( "yyyyMMdd" )); //自定义编号规则 String hashColVal = hashCol + "00001" ; // redisTemplate.opsForHash().putIfAbsent(hashName, hashCol, hashColVal); Long expiresTime = getSecondsNextEarlyMorning(); redisTemplate.opsForValue().set(key, Long.valueOf(hashColVal), expiresTime, TimeUnit.SECONDS); return hashColVal; } /** * 获取分布式Id * @param key * @return */ public String getPrimaryId(String key) { String id = "" ; if (redisTemplate.hasKey(key)){ // redisTemplate.opsForValue().get(key); // redisTemplate.delete(key); id = String.valueOf(redisTemplate.opsForValue().increment(key, 1 )); } else { id = initPrimaryId(key); } return id; } /** * 判断当前时间距离第二天凌晨的秒数 * @return 返回值单位为[s:秒] */ public Long getSecondsNextEarlyMorning() { Calendar cal = Calendar.getInstance(); cal.add(Calendar.DAY_OF_YEAR, 1 ); cal.set(Calendar.HOUR_OF_DAY, 0 ); cal.set(Calendar.SECOND, 0 ); cal.set(Calendar.MINUTE, 0 ); cal.set(Calendar.MILLISECOND, 0 ); return (cal.getTimeInMillis() - System.currentTimeMillis()) / 1000 ; } } |
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原文链接:https://blog.csdn.net/qq_45721579/article/details/125359490