C# 版算法：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Threading.Tasks;
6
7 namespace Demo
8 {
9
10 /// <summary>
11 /// 根据twitter的snowflake算法生成唯一ID
12 /// snowflake算法 64 位
13 /// 0---0000000000 0000000000 0000000000 0000000000 0 --- 00000 ---00000 ---000000000000
14 /// 第一位为未使用（实际上也可作为long的符号位），接下来的41位为毫秒级时间，然后5位datacenter标识位，5位机器ID（并不算标识符，实际是为线程标识），然后12位该毫秒内的当前毫秒内的计数，加起来刚好64位，为一个Long型。
15 /// 其中datacenter标识位起始是机器位，机器ID其实是线程标识，可以同一一个10位来表示不同机器
16 /// </summary>
17 public class IdWorker
18 {
19 //机器ID
20 private static long workerId = 1;
21 private static long twepoch = 687888001020L; //唯一时间，这是一个避免重复的随机量，自行设定不要大于当前时间戳
22 private static long sequence = 0L;
23 private static int workerIdBits = 4; //机器码字节数。4个字节用来保存机器码
24 public static long maxWorkerId = -1L ^ -1L << workerIdBits; //最大机器ID
25 private static int sequenceBits = 10; //计数器字节数，10个字节用来保存计数码
26 private static int workerIdShift = sequenceBits; //机器码数据左移位数，就是后面计数器占用的位数
27 private static int timestampLeftShift = sequenceBits + workerIdBits; //时间戳左移动位数就是机器码和计数器总字节数
28 public static long sequenceMask = -1L ^ -1L << sequenceBits; //一微秒内可以产生计数，如果达到该值则等到下一微妙在进行生成
29 private long lastTimestamp = -1L;
30
31 public long nextId()
32 {
33 lock (this)
34 {
35 long timestamp = timeGen();
36 if (this.lastTimestamp == timestamp)
37 { //同一微妙中生成ID
38 IdWorker.sequence = (IdWorker.sequence + 1) & IdWorker.sequenceMask; //用&运算计算该微秒内产生的计数是否已经到达上限
39 if (IdWorker.sequence == 0)
40 {
41 //一微妙内产生的ID计数已达上限，等待下一微妙
42 timestamp = tillNextMillis(this.lastTimestamp);
43 }
44 }
45 else
46 { //不同微秒生成ID
47 IdWorker.sequence = 0; //计数清0
48 }
49 if (timestamp < lastTimestamp)
50 { //如果当前时间戳比上一次生成ID时时间戳还小，抛出异常，因为不能保证现在生成的ID之前没有生成过
51 throw new Exception(string.Format("Clock moved backwards. Refusing to generate id for {0} milliseconds",
52 this.lastTimestamp - timestamp));
53 }
54 this.lastTimestamp = timestamp; //把当前时间戳保存为最后生成ID的时间戳
55 long nextId = (timestamp - twepoch << timestampLeftShift) | IdWorker.workerId << IdWorker.workerIdShift | IdWorker.sequence;
56 return nextId;
57 }
58 }
59
60 /// <summary>
61 /// 获取下一微秒时间戳
62 /// </summary>
63 /// <param name="lastTimestamp"></param>
64 /// <returns></returns>
65 private long tillNextMillis(long lastTimestamp)
66 {
67 long timestamp = timeGen();
68 while (timestamp <= lastTimestamp)
69 {
70 timestamp = timeGen();
71 }
72 return timestamp;
73 }
74
75 /// <summary>
76 /// 生成当前时间戳
77 /// </summary>
78 /// <returns></returns>
79 private long timeGen()
80 {
81 return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
82 }
83 }
84 }
Java 版算法：
1 import org.slf4j.Logger;
2 import org.slf4j.LoggerFactory;
3 import org.springframework.stereotype.Component;
4
5 public class IdWorker {
6
7 protected static final Logger LOG = LoggerFactory.getLogger(IdWorker.class);
8
9 private long workerId;
10 private long datacenterId;
11 private long sequence = 0L;
12
13 private long twepoch = 1288834974657L;
14
15 private long workerIdBits = 5L;
16 private long datacenterIdBits = 5L;
17 private long maxWorkerId = -1L ^ (-1L << workerIdBits);
18 private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
19 private long sequenceBits = 12L;
20
21 private long workerIdShift = sequenceBits;
22 private long datacenterIdShift = sequenceBits + workerIdBits;
23 private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
24 private long sequenceMask = -1L ^ (-1L << sequenceBits);
25
26 private long lastTimestamp = -1L;
27
28 public IdWorker(long workerId, long datacenterId) {
29 // sanity check for workerId
30 if (workerId > maxWorkerId || workerId < 0) {
31 throw new IllegalArgumentException(String.format("worker Id can‘t be greater than %d or less than 0", maxWorkerId));
32 }
33 if (datacenterId > maxDatacenterId || datacenterId < 0) {
34 throw new IllegalArgumentException(String.format("datacenter Id can‘t be greater than %d or less than 0", maxDatacenterId));
35 }
36 this.workerId = workerId;
37 this.datacenterId = datacenterId;
38 LOG.info(String.format("worker starting. timestamp left shift %d, datacenter id bits %d, worker id bits %d, sequence bits %d, workerid %d", timestampLeftShift, datacenterIdBits, workerIdBits, sequenceBits, workerId));
39 }
40
41 public synchronized long nextId() {
42 long timestamp = timeGen();
43
44 if (timestamp < lastTimestamp) {
45 LOG.error(String.format("clock is moving backwards. Rejecting requests until %d.", lastTimestamp));
46 throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
47 }
48
49 if (lastTimestamp == timestamp) {
50 sequence = (sequence + 1) & sequenceMask;
51 if (sequence == 0) {
52 timestamp = tilNextMillis(lastTimestamp);
53 }
54 } else {
55 sequence = 0L;
56 }
57
58 lastTimestamp = timestamp;
59
60 return ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift) | (workerId << workerIdShift) | sequence;
61 }
62
63 protected long tilNextMillis(long lastTimestamp) {
64 long timestamp = timeGen();
65 while (timestamp <= lastTimestamp) {
66 timestamp = timeGen();
67 }
68 return timestamp;
69 }
70
71 protected long timeGen() {
72 return System.currentTimeMillis();
73 }
74
75
76 }
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时间： 2024-10-10 08:16:25