プロジェクトがグローバル一意のidプライマリ・キーを生成する方法

一.新規自己増分リスト方式
mysqlを使用して、idだけが自動的に増加するテーブルを新規作成し、idを取得するたびに、まず自己増順リストにデータを書き込み、idを取得します.

CREATE TABLE `org_dept`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`) USING BTREE
); 

欠点:
1.ライブラリシーンには適用されません
2.特高同時シーンには適用されません
メリット:
1.mysqlデータベース自体によるシンプル化
二.新規シーケンス方式
Oracle、SQLserverに適用

--      1    ：
create sequence seq_id increment 1 start 1000000000000 ;

--      2    ：
create sequence seq_id increment 1 start 2000000000000 ;

--       
create table t_table_name(
  n_id bigint not null default nextval('seq_id'), --          
--     
primary key(n_id)
);

メリット:
1.適用ライブラリ表
三.UUID方式
UUIDにより生成
メリット:
1.第三者に依存しない
欠点:
1.不連続
四.スノーアルゴリズム

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import lombok.ToString;

/**   
* Copyright: Copyright (c) 2019 
* 
* @ClassName: IdWorker.java
* @Description: 
SnowFlake   ，  Twitter        id     。
* 					       ：     64 bit   long            id。
* 					  64   bit  ，   1   bit     ，       41 bit      ，
* 					  10 bit        id，12 bit      
*				
* @version: v1.0.0
* @author: BianPeng
* @date: 2019 4 11    3:13:41 
*
* Modification History:
* Date         		Author          Version          Description
*---------------------------------------------------------------*
* 2019 4 11       		BianPeng        v1.0.0           initialize
*/
@ToString
public class SnowflakeIdFactory {
 
	static Logger log = LoggerFactory.getLogger(SnowflakeIdFactory.class);
	
    private final long twepoch = 1288834974657L;
    private final long workerIdBits = 5L;
    private final long datacenterIdBits = 5L;
    private final long maxWorkerId = -1L ^ (-1L << workerIdBits);
    private final long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
    private final long sequenceBits = 12L;
    private final long workerIdShift = sequenceBits;
    private final long datacenterIdShift = sequenceBits + workerIdBits;
    private final long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
    private final long sequenceMask = -1L ^ (-1L << sequenceBits);
 
    private long workerId;
    private long datacenterId;
    private long sequence = 0L;
    private long lastTimestamp = -1L;
 
 
 
    public SnowflakeIdFactory(long workerId, long datacenterId) {
        if (workerId > maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
        }
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
            throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
        }
        this.workerId = workerId;
        this.datacenterId = datacenterId;
    }
 
    public synchronized long nextId() {
        long timestamp = timeGen();
        if (timestamp < lastTimestamp) {
            //         ,ID       .
            throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
        }
        if (lastTimestamp == timestamp) {
            sequence = (sequence + 1) & sequenceMask;
            if (sequence == 0) {
                timestamp = tilNextMillis(lastTimestamp);
            }
        } else {
            sequence = 0L;
        }
 
        lastTimestamp = timestamp;
        return ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift) | (workerId << workerIdShift) | sequence;
    }
 
    protected long tilNextMillis(long lastTimestamp) {
        long timestamp = timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = timeGen();
        }
        return timestamp;
    }
 
    protected long timeGen() {
        return System.currentTimeMillis();
    }
 
    public static void testProductIdByMoreThread(int dataCenterId, int workerId, int n) throws InterruptedException {
        List tlist = new ArrayList<>();
        Set setAll = new HashSet<>();
        CountDownLatch cdLatch = new CountDownLatch(10);
        long start = System.currentTimeMillis();
        int threadNo = dataCenterId;
        Map idFactories = new HashMap<>();
        for(int i=0;i<10;i++){
            //      map key.
            idFactories.put("snowflake"+i,new SnowflakeIdFactory(workerId, threadNo++));
        }
        for(int i=0;i<10;i++){
            Thread temp =new Thread(new Runnable() {
                @Override
                public void run() {
                    Set setId = new HashSet<>();
                    SnowflakeIdFactory idWorker = idFactories.get(Thread.currentThread().getName());
                    for(int j=0;j setOne = new HashSet<>();
        Set setTow = new HashSet<>();
        long start = System.currentTimeMillis();
        for (int i = 0; i < n; i++) {
            setOne.add(idWorker.nextId());//  set
        }
        long end1 = System.currentTimeMillis() - start;
        log.info("   ID    {} ,    {} <<<>>>   :{}",n,setOne.size(),end1);
 
        for (int i = 0; i < n; i++) {
            setTow.add(idWorker2.nextId());//  set
        }
        long end2 = System.currentTimeMillis() - start;
        log.info("   ID    {} ,    {} <<<>>>   :{}",n,setTow.size(),end2);
 
        setOne.addAll(setTow);
        log.info("      ID  :{}",setOne.size());
 
    }
 
    public static void testPerSecondProductIdNums(){
        SnowflakeIdFactory idWorker = new SnowflakeIdFactory(1, 2);
        long start = System.currentTimeMillis();
        int count = 0;
        for (int i = 0; System.currentTimeMillis()-start<1000; i++,count=i) {
            /**       :         ID,    ID   400w+ */
        	//idWorker.nextId();
            /**       :  log   ,    ID,     ID      log.error()     .
             *      10   . */
        	log.info(""+idWorker.nextId());
        }
        long end = System.currentTimeMillis()-start;
        System.out.println(end);
        System.out.println(count);
    }
 
    public static void main(String[] args) {
        /** case1:       id  ?
         *     :     id  400w+ 
         */
        //testPerSecondProductIdNums();
 
        /** case2:    -           N id,  id     ?
         *     :     ,    . 
         */
        //testProductId(1,2,10000);//    !
        //testProductId(1,2,20000);//    !
 
        /** case3:    -           N id,   id           ?
         *     :     ,    .
         */
        try {
            testProductIdByMoreThread(1,2,100000);//       ,        !
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
 
    }
}

メリット:
1.第三者に依存しない
2.実現が簡単
3.適用ライブラリ表