分布式之全局主键

不念不忘少年蓝@ 2022-03-28 09:29 203阅读 0赞

在应用中，我们通常需要对各个项目中的各个库表的主键进行统一的获取分配，一般来说，我们会将此项目注册到Eureka上面，供其他项目有入库操作时调用，此处仅为了演示，所以没有将其注册到Eureka

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI0MzEzNjM1_size_16_color_FFFFFF_t_70][]

pom.xml文件

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    
    	<groupId>com.yj</groupId>
    	<artifactId>IdCenter</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>IdCenter</name>
    	<url>http://maven.apache.org</url>
    
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    	</properties>
    
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>1.5.17.RELEASE</version>
    		<relativePath />
    	</parent>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.apache.commons</groupId>
    			<artifactId>commons-lang3</artifactId>
    			<version>3.8.1</version>
    		</dependency>
    	</dependencies>
    </project>

GlobalIdController

package com.yj.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.ResponseBody;
    import com.yj.exception.BusinessException;
    import com.yj.service.CreateGlobalIdService;
    
    @Controller
    public class GlobalIdController {
    
    	@Autowired
    	private CreateGlobalIdService createGlobalIdService;
    
    	@RequestMapping(value = "/createGlobalId", method = RequestMethod.GET)
    	@ResponseBody
    	public Object createGlobalId() {
    		String result = null;
    		try {
    			result = createGlobalIdService.getId();
    		} catch (BusinessException e) {
    			e.printStackTrace();
    		}
    		return result;
    	}
    }

CreateGlobalIdService

package com.yj.service;
    
    import java.util.HashMap;
    import java.util.Map;
    import org.apache.commons.lang3.StringUtils;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.stereotype.Service;
    import com.yj.util.IdWorker;
    
    @Service
    public class CreateGlobalIdService {
    
    	@Value("${dataCenterId}")
    	private Integer dataCenterId;
    	@Value("${workId}")
    	private Integer workId;
    
    	private static final Map<String, IdWorker> workMap = new HashMap<String, IdWorker>();
    
    	public String getId() {
    		IdWorker idWorker = workMap.get(dataCenterId + "_" + workId);
    		if (idWorker != null) {
    			return StringUtils.leftPad(Long.toHexString(idWorker.nextId()), 16, "0");
    		}
    		idWorker = new IdWorker(dataCenterId, workId);
    		workMap.put(dataCenterId + "_" + workId, idWorker);
    		return StringUtils.leftPad(Long.toHexString(idWorker.nextId()), 16, "0");
    	}
    }

IdWorker

package com.yj.util;
    
    public class IdWorker {
    	// 主机编号
    	private long workerId;
    	// 机房编号
    	private long datacenterId;
    	private long sequence = 0L;
    	// 正式运行之日，重新计算一个新值
    	private static long twepoch = 1444721918651L;
    	// 机器标识位数
    	private long workerIdBits = 5L;
    	// 数据中心标识位数
    	private long datacenterIdBits = 5L;
    	// 主机编号（从0开始的序列）最大值
    	private long maxWorkerId = -1L ^ (-1L << workerIdBits);
    	// 机房编号（从0开始的序列）最大值
    	private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
    	// 毫秒内自增位
    	private long sequenceBits = 12L;
    	// 机器ID偏左移12位
    	private long workerIdShift = sequenceBits;
    	// 数据中心ID左移17位
    	private long datacenterIdShift = sequenceBits + workerIdBits;
    	// 时间毫秒左移22位
    	private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
    	private long sequenceMask = -1L ^ (-1L << sequenceBits);
    
    	private long lastTimestamp = -1L;
    
    	public IdWorker(long datacenterId, long workerId) {
    		if (workerId > maxWorkerId || workerId < 0) {
    			throw new IllegalArgumentException(
    					String.format("workerId 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 = this.timeGen();
    		if (this.lastTimestamp == timestamp) {
    			this.sequence = (this.sequence + 1) & sequenceMask;
    			if (this.sequence == 0) {
    				timestamp = this.tilNextMillis(this.lastTimestamp);
    			}
    		} else {
    			this.sequence = 0;
    		}
    		if (timestamp < this.lastTimestamp) {
    			try {
    				throw new Exception(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds",
    						this.lastTimestamp - timestamp));
    			} catch (Exception e) {
    				e.printStackTrace();
    			}
    		}
    		this.lastTimestamp = timestamp;
    		long nextId = ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift)
    				| (workerId << workerIdShift) | sequence;
    		return nextId;
    	}
    
    	private long tilNextMillis(final long lastTimestamp) {
    		long timestamp = this.timeGen();
    		while (timestamp <= lastTimestamp) {
    			timestamp = this.timeGen();
    		}
    		return timestamp;
    	}
    
    	private long timeGen() {
    		return System.currentTimeMillis();
    	}
    }

application.properties

server.port=80
    dataCenterId=0
    workId=0

我们启动此项目，然后访问

http://127.0.0.1/createGlobalId

获取到了全局ID：05f5596975000000

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