雪花算法使用教程

雪花算法使用教程

首先创建工具类RandomIDUtil

/**
 * 随机数
 *
 */
public class RandomIDUtil {

	/**
	 * 起始的时间戳
	 */
	private final static long START_STMP = 1480166465631L;

	/**
	 * 每一部分占用的位数
	 */
	private final static long SEQUENCE_BIT = 12; // 序列号占用的位数
	private final static long MACHINE_BIT = 5; // 机器标识占用的位数
	private final static long DATACENTER_BIT = 5;// 数据中心占用的位数

	/**
	 * 每一部分的最大值
	 */
	private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
	private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
	private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);

	/**
	 * 每一部分向左的位移
	 */
	private final static long MACHINE_LEFT = SEQUENCE_BIT;
	private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
	private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;

	private long datacenterId; // 数据中心
	private long machineId; // 机器标识
	private long sequence = 0L; // 序列号
	private long lastStmp = -1L;// 上一次时间戳

	/**
	 * 
	 * @param datacenterId
	 * @param machineId
	 */
	public RandomIDUtil(long datacenterId, long machineId) {
		if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
			throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
		}
		if (machineId > MAX_MACHINE_NUM || machineId < 0) {
			throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
		}
		this.datacenterId = datacenterId;
		this.machineId = machineId;
	}

	/**
	 * 产生下一个ID
	 *
	 * @return
	 */
	public synchronized long nextId() {
		long currStmp = getNewstmp();
		if (currStmp < lastStmp) {
			throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
		}

		if (currStmp == lastStmp) {
			// 相同毫秒内，序列号自增
			sequence = (sequence + 1) & MAX_SEQUENCE;
			// 同一毫秒的序列数已经达到最大
			if (sequence == 0L) {
				currStmp = getNextMill();
			}
		} else {
			// 不同毫秒内，序列号置为0
			sequence = 0L;
		}

		lastStmp = currStmp;

		return (currStmp - START_STMP) << TIMESTMP_LEFT // 时间戳部分
				| datacenterId << DATACENTER_LEFT // 数据中心部分
				| machineId << MACHINE_LEFT // 机器标识部分
				| sequence; // 序列号部分
	}

	private long getNextMill() {
		long mill = getNewstmp();
		while (mill <= lastStmp) {
			mill = getNewstmp();
		}
		return mill;
	}

	private long getNewstmp() {
		return System.currentTimeMillis();
	}
}

写一个启动服务

首先写个公共的服务

public interface BaseService {

	/**
	 * 初始化服务【系统自身调用】
	 */
	public void init();

	/**
	 * 生成分布式随机数
	 * 
	 * @return
	 */
	public String getRandomID();

}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;

import com.example.demo.service.BaseService;
import com.example.demo.utils.RandomIDUtil;

@Component
public class BaseServiceImpl implements BaseService {
	@Autowired
	private Environment env;
	private RandomIDUtil randomIDUtil;

	@Override
	public void init() {
		// TODO Auto-generated method stub
		if (randomIDUtil == null) {
			randomIDUtil = new RandomIDUtil(Long.valueOf(env.getProperty("datacenterId")),
					Long.valueOf(env.getProperty("machineId")));
		}
	}

	@Override
	public String getRandomID() {
		return String.valueOf(randomIDUtil.nextId());
	}

}

@Component
public class BaseServiceImpl implements BaseService {
	@Autowired
	private Environment env;
	private RandomIDUtil randomIDUtil;

	@Override
	public void init() {
		// TODO Auto-generated method stub
		if (randomIDUtil == null) {
			randomIDUtil = new RandomIDUtil(Long.valueOf(env.getProperty("datacenterId")),
					Long.valueOf(env.getProperty("machineId")));
		}
	}

	@Override
	public String getRandomID() {
		return String.valueOf(randomIDUtil.nextId());
	}

}

创建几个初始化类

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import com.example.demo.service.BaseService;

import lombok.extern.slf4j.Slf4j;

@Component
@Order(value = 1)
@Slf4j
public class BaseServiceInitRunner implements ApplicationRunner {

	@Autowired
	BaseService baseService;
	
	@Override
	public void run(ApplicationArguments args) throws Exception {
		// TODO Auto-generated method stub
		baseService.init();
		log.info("\n===============================\nBase Service Init Success\n===============================");
	}
}

最后直接调用就可以了

	@Autowired
	BaseService baseService;
String memberId = baseService.getRandomID();