雪花算法工厂

package io.binghe.seckill.infrastructure.utils.id;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

 
public class SnowFlakeFactory {	
	
	/**
	 * 默认数据中心id
	 */
	private static final long DEFAULT_DATACENTER_ID = 1;
	/**
	 * 默认的机器id
	 */
	private static final long DEFAULT_MACHINE_ID = 1;
	
	/**
	 * 默认的雪花算法句柄
	 */
	private static final String DEFAULT_SNOW_FLAKE = "snow_flake";
	
	/**
	 * 缓存SnowFlake对象
	 */
	private static ConcurrentMap<String, SnowFlake> snowFlakeCache = new ConcurrentHashMap<>(2);
	
	public static SnowFlake getSnowFlake(long datacenterId, long machineId) {
		return new SnowFlake(datacenterId, machineId);
	}
	
	public static SnowFlake getSnowFlake() {
		return new SnowFlake(DEFAULT_DATACENTER_ID, DEFAULT_MACHINE_ID);
	}
	
	public static SnowFlake getSnowFlakeFromCache() {
		SnowFlake snowFlake = snowFlakeCache.get(DEFAULT_SNOW_FLAKE);
		if(snowFlake == null) {
			snowFlake = new SnowFlake(DEFAULT_DATACENTER_ID, DEFAULT_MACHINE_ID);
			snowFlakeCache.put(DEFAULT_SNOW_FLAKE, snowFlake);
		}
		return snowFlake;
	}
	
	/**
	 * 根据数据中心id和机器id从缓存中获取全局id
	 * @param dataCenterId: 取值为1~31
	 * @param machineId: 取值为1~31
	 */
	public static SnowFlake getSnowFlakeByDataCenterIdAndMachineIdFromCache(Long dataCenterId, Long machineId) {
	  if (dataCenterId > SnowFlake.getMaxDataCeneterNum() || dataCenterId < 0) {
            throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
        }
        if (machineId > SnowFlake.getMaxMachineNum() || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
        }
		String key = DEFAULT_SNOW_FLAKE.concat("_").concat(String.valueOf(dataCenterId)).concat("_").concat(String.valueOf(machineId));
		SnowFlake snowFlake = snowFlakeCache.get(key);
		if(snowFlake == null) {
			snowFlake = new SnowFlake(dataCenterId, machineId);
			snowFlakeCache.put(key, snowFlake);
		}
		return snowFlake;
	}
	
	public static void main(String[] args) {
		for(int i = 0; i < 100; i++) {
			System.out.println(getSnowFlakeFromCache().nextId());
		}
	}
}