Redis实现全局唯一id

redis实现全局唯一id

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import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

@Component
public class RedisIdWorker {

    private StringRedisTemplate stringRedisTemplate;

    private static final long BEGIN_TIMESTAMP = 1640995200L;
    private static final int COUNT_BITS = 32;
    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public long nextId(String keyPrefix){
        // 生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowSecond - BEGIN_TIMESTAMP;
        // 生成序列号
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        long count = stringRedisTemplate.opsForValue().increment("icr:" + keyPrefix + ":" + date);
        return timestamp << COUNT_BITS | count;
    }
}

timestamp << COUNT_BITS | count :

将timestamp 向左移动32位,再和count做或运算

• 获取指定日期的时间戳

	@Test
    void test() throws Exception{
        LocalDateTime dateTime = LocalDateTime.of(2022, 1, 1, 0, 0, 0);
        long epochSecond = dateTime.toEpochSecond(ZoneOffset.UTC);
        System.out.println("epochSecond = " + epochSecond);
    }

• 其他全局ID生成策略
  • UUID
  • redis自增
  • 雪花算法
  • 数据库自增 (单独一张自增表)