package com.aiyusheng.shopping.util;

import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
*

名称：IdWorker.java

*

描述：分布式自增长ID

*

  
 *     Twitter的 Snowflake　JAVA实现方案  
 * 

* 核心代码为其IdWorker这个类实现，其原理结构如下，我分别用一个0表示一位，用—分割开部分的作用：
* 1||0---0000000000 0000000000 0000000000 0000000000 0 --- 00000 ---00000 ---000000000000
* 在上面的字符串中，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。
* 这样的好处是，整体上按照时间自增排序，并且整个分布式系统内不会产生ID碰撞（由datacenter和机器ID作区分），
* 并且效率较高，经测试，snowflake每秒能够产生26万ID左右，完全满足需要。
*

* 64位ID (42(毫秒)+5(机器ID)+5(业务编码)+12(重复累加))
*
* @author Polim
*/
public class IdWorker {
// 时间起始标记点，作为基准，一般取系统的最近时间（一旦确定不能变动）
private final static long TWEPOCH= 1288834974657L;
// 机器标识位数
private final static long WORKDER_ID_BITS = 5L;
// 数据中心标识位数
private final static long DATACENTER_ID_BITS = 5L;
// 机器ID最大值
private final static long MAX_WORKDER_ID= -1L ^ (-1L << WORKDER_ID_BITS);
// 数据中心ID最大值
private final static long MAX_DATACENTER_ID= -1L ^ (-1L << DATACENTER_ID_BITS);
// 毫秒内自增位
private final static long SEQUENCE_BITS= 12L;
// 机器ID偏左移12位
private final static long WORKDER_ID_SHIFT= SEQUENCE_BITS;
// 数据中心ID左移17位
private final static long DATACENTER_ID_SHIFT= SEQUENCE_BITS + WORKDER_ID_BITS;
// 时间毫秒左移22位
private final static long TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKDER_ID_BITS + SEQUENCE_BITS;

private final static long  SEQUENCE\_MASK= -1L ^ (-1L << SEQUENCE\_BITS);  
/\* 上次生产id时间戳 \*/  
private static long lastTimestamp = -1L;  
// 0，并发控制  
private long sequence = 0L;

private final long workerId;  
// 数据标识id部分  
private final long datacenterId;

public IdWorker(){  
    this.datacenterId = getDatacenterId(MAX\_DATACENTER\_ID);  
    this.workerId = getMaxWorkerId(datacenterId, MAX\_WORKDER\_ID);  
}  
/\*\*  
 \* @param workerId  
 \*            工作机器ID  
 \* @param datacenterId  
 \*            序列号  
 \*/  
public IdWorker(long workerId, long datacenterId) {  
    if (workerId > MAX\_WORKDER\_ID || workerId < 0) {  
        throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", MAX\_WORKDER\_ID));  
    }  
    if (datacenterId > MAX\_WORKDER\_ID || datacenterId < 0) {  
        throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", MAX\_DATACENTER\_ID));  
    }  
    this.workerId = workerId;  
    this.datacenterId = datacenterId;  
}  
/\*\*  
 \* 获取下一个ID  
 \*  
 \* @return  
 \*/  
public synchronized long nextId() {  
    long timestamp = timeGen();  
    if (timestamp < lastTimestamp) {  
        throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));  
    }

    if (lastTimestamp == timestamp) {  
        // 当前毫秒内，则+1  
        sequence = (sequence + 1) & SEQUENCE\_MASK;  
        if (sequence == 0) {  
            // 当前毫秒内计数满了，则等待下一秒  
            timestamp = tilNextMillis(lastTimestamp);  
        }  
    } else {  
        sequence = 0L;  
    }  
    lastTimestamp = timestamp;  
    // ID偏移组合生成最终的ID，并返回ID  
    long nextId = ((timestamp - TWEPOCH) << TIMESTAMP\_LEFT\_SHIFT)  
            | (datacenterId << DATACENTER\_ID\_SHIFT)  
            | (workerId << WORKDER\_ID\_SHIFT) | sequence;

    return nextId;  
}

/\*\*  
 \* 功能描述： 自动补全生成32位  
 \* @Param:  
 \* @Return: java.lang.String  
 \* @Author: chenzhian  
 \* @Date: 2020/12/2 17:24  
 \* @Description:  
 \*/  
public synchronized String next32Id(){  
    String Id=  nextId()+"";  
    String nowtime = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date());  
    Integer surplusLength=32-Id.length()-nowtime.length();  
    if(surplusLength>0){  
        //自动补缺数字  
        String strsurplus = String.format("%0"+surplusLength+"d", 0);  
        return nowtime+strsurplus+Id;  
    }else if(surplusLength==0){  
        return nowtime+Id;  
    }else{  
        return nowtime.substring(0,(nowtime.length()+surplusLength))+Id;  
    }  
}

/\*\*  
 \* 阻塞到下一个毫秒，直到获得新的时间戳  
 \* @param lastTimestamp 上次生成ID的时间截  
 \* @return 当前时间戳  
 \*/  
private long tilNextMillis(final long lastTimestamp) {  
    long timestamp = this.timeGen();  
    while (timestamp <= lastTimestamp) {  
        timestamp = this.timeGen();  
    }  
    return timestamp;  
}

/\*\*  
 \* 返回以毫秒为单位的当前时间  
 \* @return 当前时间(毫秒)  
 \*/  
private long timeGen() {  
    return System.currentTimeMillis();  
}

/\*\*  
 \* <p>  
 \* 获取 maxWorkerId  
 \* </p>  
 \*/  
protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {  
    StringBuffer mpid = new StringBuffer();  
    mpid.append(datacenterId);  
    String name = ManagementFactory.getRuntimeMXBean().getName();  
    if (!name.isEmpty()) {  
     /\*  
      \* GET jvmPid  
      \*/  
        mpid.append(name.split("@")\[0\]);  
    }  
  /\*  
   \* MAC + PID 的 hashcode 获取16个低位  
   \*/  
    return (mpid.toString().hashCode() & 0xffff) % (maxWorkerId + 1);  
}

/\*\*  
 \* <p>  
 \* 数据标识id部分  
 \* </p>  
 \*/  
protected static long getDatacenterId(long maxDatacenterId) {  
    long id = 0L;  
    try {  
        InetAddress ip = InetAddress.getLocalHost();  
        NetworkInterface network = NetworkInterface.getByInetAddress(ip);  
        if (network == null) {  
            id = 1L;  
        } else {  
            byte\[\] mac = network.getHardwareAddress();  
            id = ((0x000000FF & (long) mac\[mac.length - 1\])  
                    | (0x0000FF00 & (((long) mac\[mac.length - 2\]) << 8))) >> 6;  
            id = id % (maxDatacenterId + 1);  
        }  
    } catch (Exception e) {  
        System.out.println(" getDatacenterId: " + e.getMessage());  
    }  
    return id;  
}

}

package com.aiyusheng.shopping.config;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "ly.worker")
public class IdWorkerProperties {

private long workerId;// 当前机器id

private long datacenterId;// 序列号

public long getWorkerId() {  
    return workerId;  
}

public void setWorkerId(long workerId) {  
    this.workerId = workerId;  
}

public long getDatacenterId() {  
    return datacenterId;  
}

public void setDatacenterId(long datacenterId) {  
    this.datacenterId = datacenterId;  
}  

}

package com.aiyusheng.shopping.config;

import com.aiyusheng.shopping.util.IdWorker;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableConfigurationProperties(IdWorkerProperties.class)
public class IdWorkerConfig {

@Bean  
public IdWorker idWorker(IdWorkerProperties prop) {  
    return new IdWorker(prop.getWorkerId(), prop.getDatacenterId());  
}  

}

配置文件application.properties

ly.worker.workerId=1
ly.worker.datacenterId=1