实际的代码 贴出作为大家的参考：
package net.study.framework.orm.id;
import java.util.Random;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.SmartInitializingSingleton;
/**
* 基于Twitter的ID生成器算法的全局唯一ID生成器
*/
public class TwitterLongIdGenerator implements IdGenerator<Long>, SmartInitializingSingleton {
private static Logger logger = LoggerFactory.getLogger(TwitterLongIdGenerator.class);
public static final String WORKER_ID_PROP = "study.worker.id";
public static final String DATACENTER_ID_PROP = "study.datacenter.id";
private long sequence = 0L;
private long epoch = 30 * 365 * 24 * 3600000L; // 时间纪元 2000-01-01 00:00 00
private long workerIdBits = 5L; // 节点ID长度
private long datacenterIdBits = 5L; // 数据中心ID长度
private long maxWorkerId = -1L ^ (-1L << workerIdBits); // 最大支持机器节点数0~31，一共32个
private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits); // 最大支持数据中心节点数0~31，一共32个
private long sequenceBits = 12L; // 序列号12位
private long workerIdShift = sequenceBits; // 机器节点左移12位
private long datacenterIdShift = sequenceBits workerIdBits; // 数据中心节点左移17位
private long timestampLeftShift = sequenceBits workerIdBits datacenterIdBits; // 时间毫秒数左移22位
private long sequenceMask = -1L ^ (-1L << sequenceBits); // 4095
private long incrementBits = 10L; // 默认自增10位
private long incrementMask = -1L ^ (-1L << incrementBits); // 1024，自增到1024时从0重新开始自增
private long lastTimestamp = -1L;
private long workerId;// 支持机器节点数0~31，最多32个
private long datacenterId;// 支持数据中心节点数0~31，最多32个
/**
* workerId和datacenterId从系统变量读取，若没有设置系统变量则随机一个
*/
public TwitterLongIdGenerator() {
Random random = new Random();
int randomWorker = random.nextInt(Long.valueOf(maxWorkerId).intValue());
String worker = System.getProperty(WORKER_ID_PROP, String.valueOf(randomWorker));
long workerId = Long.valueOf(worker);
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException( String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
int randomDatacenter = random.nextInt(Long.valueOf(maxDatacenterId).intValue());
String datacenter = System.getProperty(DATACENTER_ID_PROP, String.valueOf(randomDatacenter));
long datacenterId = Long.valueOf(datacenter);
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;
logger.info("Init TwitterLongIdGenerator width workerId:{} datacenterId:{}", workerId, datacenterId);
}
public synchronized long nextId() {
long timestamp = timeGen(); // 获取当前毫秒数
// 如果服务器时间有问题(时钟后退) 报错
if (timestamp < lastTimestamp) {
throw new RuntimeException(String.format(
"Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
// 如果上次生成时间和当前时间相同,在同一毫秒内
if (lastTimestamp == timestamp) {
// sequence自增，因为sequence只有12bit，所以和sequenceMask相与一下，去掉高位
sequence = (sequence 1) & sequenceMask;
// 判断是否溢出,也就是每毫秒内超过4095，当为4096时，与sequenceMask相与，sequence就等于0
if (sequence == 0) {
timestamp = tilNextMillis(lastTimestamp); // 自旋等待到下一毫秒
}
} else {
// 如果和上次生成时间不同,自增sequence，到incrementMask（1024）时，sequence计数重新从0开始累加
sequence = (sequence 1) & incrementMask;
}
lastTimestamp = timestamp;
// 最后按照规则拼出ID
// 000000000000000000000000000000000000000000 00000 00000 000000000000
// time datacenterId workerId sequence
return ((timestamp - epoch) << timestampLeftShift) | (datacenterId << datacenterIdShift)
| (workerId << workerIdShift) | sequence;
}
/**
* 保证同一毫秒内的序列号不会重复
* @param lastTimestamp
* @return
*/
private long tilNextMillis(long lastTime) {
long timestamp = timeGen();
while (timestamp <= lastTime) {
timestamp = timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
@Override
public Long generate() {
return nextId();
}
@Override
public void afterSingletonsInstantiated() {
LongIdGenerator.setIdGeneratorInstance(this);
}
}
，下面我们就来聊聊关于自定义分布式id生成器?接下来我们就一起去了解一下吧!
自定义分布式id生成器
实际的代码 贴出作为大家的参考：
package net.study.framework.orm.id;
import java.util.Random;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.SmartInitializingSingleton;
/**
* 基于Twitter的ID生成器算法的全局唯一ID生成器
*/
public class TwitterLongIdGenerator implements IdGenerator<Long>, SmartInitializingSingleton {
private static Logger logger = LoggerFactory.getLogger(TwitterLongIdGenerator.class);
public static final String WORKER_ID_PROP = "study.worker.id";
public static final String DATACENTER_ID_PROP = "study.datacenter.id";
private long sequence = 0L;
private long epoch = 30 * 365 * 24 * 3600000L; // 时间纪元 2000-01-01 00:00 00
private long workerIdBits = 5L; // 节点ID长度
private long datacenterIdBits = 5L; // 数据中心ID长度
private long maxWorkerId = -1L ^ (-1L << workerIdBits); // 最大支持机器节点数0~31，一共32个
private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits); // 最大支持数据中心节点数0~31，一共32个
private long sequenceBits = 12L; // 序列号12位
private long workerIdShift = sequenceBits; // 机器节点左移12位
private long datacenterIdShift = sequenceBits workerIdBits; // 数据中心节点左移17位
private long timestampLeftShift = sequenceBits workerIdBits datacenterIdBits; // 时间毫秒数左移22位
private long sequenceMask = -1L ^ (-1L << sequenceBits); // 4095
private long incrementBits = 10L; // 默认自增10位
private long incrementMask = -1L ^ (-1L << incrementBits); // 1024，自增到1024时从0重新开始自增
private long lastTimestamp = -1L;
private long workerId;// 支持机器节点数0~31，最多32个
private long datacenterId;// 支持数据中心节点数0~31，最多32个
/**
* workerId和datacenterId从系统变量读取，若没有设置系统变量则随机一个
*/
public TwitterLongIdGenerator() {
Random random = new Random();
int randomWorker = random.nextInt(Long.valueOf(maxWorkerId).intValue());
String worker = System.getProperty(WORKER_ID_PROP, String.valueOf(randomWorker));
long workerId = Long.valueOf(worker);
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException( String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
int randomDatacenter = random.nextInt(Long.valueOf(maxDatacenterId).intValue());
String datacenter = System.getProperty(DATACENTER_ID_PROP, String.valueOf(randomDatacenter));
long datacenterId = Long.valueOf(datacenter);
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;
logger.info("Init TwitterLongIdGenerator width workerId:{} datacenterId:{}", workerId, datacenterId);
}
public synchronized long nextId() {
long timestamp = timeGen(); // 获取当前毫秒数
// 如果服务器时间有问题(时钟后退) 报错。
if (timestamp < lastTimestamp) {
throw new RuntimeException(String.format(
"Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
// 如果上次生成时间和当前时间相同,在同一毫秒内
if (lastTimestamp == timestamp) {
// sequence自增，因为sequence只有12bit，所以和sequenceMask相与一下，去掉高位
sequence = (sequence 1) & sequenceMask;
// 判断是否溢出,也就是每毫秒内超过4095，当为4096时，与sequenceMask相与，sequence就等于0
if (sequence == 0) {
timestamp = tilNextMillis(lastTimestamp); // 自旋等待到下一毫秒
}
} else {
// 如果和上次生成时间不同,自增sequence，到incrementMask（1024）时，sequence计数重新从0开始累加
sequence = (sequence 1) & incrementMask;
}
lastTimestamp = timestamp;
// 最后按照规则拼出ID。
// 000000000000000000000000000000000000000000 00000 00000 000000000000
// time datacenterId workerId sequence
return ((timestamp - epoch) << timestampLeftShift) | (datacenterId << datacenterIdShift)
| (workerId << workerIdShift) | sequence;
}
/**
* 保证同一毫秒内的序列号不会重复
* @param lastTimestamp
* @return
*/
private long tilNextMillis(long lastTime) {
long timestamp = timeGen();
while (timestamp <= lastTime) {
timestamp = timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
@Override
public Long generate() {
return nextId();
}
@Override
public void afterSingletonsInstantiated() {
LongIdGenerator.setIdGeneratorInstance(this);
}
}
