百度开源的分布式 ID 生成器，太强大了！

来源：https://lilinchao.com/archives/1226.html

一、UidGenerator是什么

UidGenerator是百度开源的一款分布式高性能的唯一ID生成器，是基于snowflake模型的一种ID生成器

二、UidGenerator的优势

解决了时钟回调的问题
使用ringbuffer,无锁进行id的生产与消费,速度非常快
适用于多线程,不会有单线程瓶颈

三、整合

本次通过SpringBoot2.x和MyBatis对百度UidGenerator进行整合。

3.1 UidGenerator引入

一般使用两种方式引入UidGenerator:

1）从官网下载源码作为自己项目的一个Module引入到项目中

官网地址：https://github.com/baidu/uid-generator/blob/master/README.zh_cn.md

2）互联网jar包引入（本文采取的是该种方式）

因为UidGenerator自带引入了mybatis，和自己项目有冲突的可以进行排除

<dependency><groupId>com.xfvape.uid</groupId><artifactId>uid-generator</artifactId><version>0.0.4-RELEASE</version>
</dependency>

排除冲突依赖

uid-generator中依赖了logback和mybatis。一般在项目搭建过程中，springboot中已经有了logback依赖，mybatis会作为单独的依赖引入。如果版本和uid-generator中的依赖不一致的话，就会导致冲突。

排除冲突的依赖如下：

<dependency><groupId>com.xfvape.uid</groupId><artifactId>uid-generator</artifactId><version>0.0.4-RELEASE</version><exclusions><exclusion><groupId>org.slf4j</groupId><artifactId>log4j-over-slf4j</artifactId></exclusion><exclusion><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId></exclusion><exclusion><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId></exclusion><exclusion><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId></exclusion><exclusion><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId></exclusion></exclusions>
</dependency>

3.2 创建表

在 MySQL数据库中建一个名为 WORKER_NODE的数据表，其 sql如下：

CREATE TABLE WORKER_NODE
(
ID BIGINT NOT NULL AUTO_INCREMENT COMMENT 'auto increment id',
HOST_NAME VARCHAR(64) NOT NULL COMMENT 'host name',
PORT VARCHAR(64) NOT NULL COMMENT 'port',
TYPE INT NOT NULL COMMENT 'node type: ACTUAL or CONTAINER',
LAUNCH_DATE DATE NOT NULL COMMENT 'launch date',
MODIFIED TIMESTAMP NOT NULL COMMENT 'modified time',
CREATED TIMESTAMP NOT NULL COMMENT 'created time',
PRIMARY KEY(ID)
)COMMENT='DB WorkerID Assigner for UID Generator',ENGINE = INNODB;

建表时可能会报错，原因是该建表语句定义了两个TIMESTAMP字段，因为mysql 低版本控制比较严格

解决办法：

方式一：

直接把TIMESTAMP改成DATETIME 即可

方式二：

建表前先设置sql_mode：

set sql_mode="NO_ENGINE_SUBSTITUTION";

3.3 将uid-generator核心对象装配为spring的bean

uid-generator提供了两种生成器: DefaultUidGenerator、CachedUidGenerator。如对UID生成性能有要求, 请使用CachedUidGenerator。

@Configuration
public class WorkerNodeConfig {@Bean("disposableWorkerIdAssigner")public DisposableWorkerIdAssigner disposableWorkerIdAssigner(){DisposableWorkerIdAssigner disposableWorkerIdAssigner = new DisposableWorkerIdAssigner();return  disposableWorkerIdAssigner;}@Bean("cachedUidGenerator")public UidGenerator uidGenerator(DisposableWorkerIdAssigner disposableWorkerIdAssigner){CachedUidGenerator cachedUidGenerator = new CachedUidGenerator();cachedUidGenerator.setWorkerIdAssigner(disposableWorkerIdAssigner);return cachedUidGenerator;}
}

直接创建WorkerNodeConfig类，复制以上代码。

3.4 重写WorkerIdAssigner接口

public class DisposableWorkerIdAssigner implements WorkerIdAssigner {@Resourceprivate WorkerNodeMapper workerNodeMapper;@Override@Transactionalpublic long assignWorkerId() {WorkerNode workerNode = buildWorkerNode();workerNodeMapper.addWorkerNode(workerNode);return workerNode.getId();}private WorkerNode buildWorkerNode() {WorkerNode workNode = new WorkerNode();if (DockerUtils.isDocker()) {workNode.setType(WorkerNodeType.CONTAINER.value());workNode.setHostName(DockerUtils.getDockerHost());workNode.setPort(DockerUtils.getDockerPort());workNode.setLaunchDate(new Date());} else {workNode.setType(WorkerNodeType.ACTUAL.value());workNode.setHostName(NetUtils.getLocalAddress());workNode.setPort(System.currentTimeMillis() + "-" + RandomUtils.nextInt(100000));workNode.setLaunchDate(new Date());}return workNode;}
}

创建一个DisposableWorkerIdAssigner类直接复制以上代码。

3.5 引入WorkerNodeMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.uidgenerator.mapper.WorkerNodeMapper"><resultMap id="BaseResultMap"type="com.uidgenerator.entity.WorkerNode"><id column="ID" jdbcType="BIGINT" property="id" /><result column="HOST_NAME" jdbcType="VARCHAR" property="hostName" /><result column="PORT" jdbcType="VARCHAR" property="port" /><result column="TYPE" jdbcType="INTEGER" property="type" /><result column="LAUNCH_DATE" jdbcType="DATE" property="launchDate" /><result column="MODIFIED" jdbcType="TIMESTAMP" property="modified" /><result column="CREATED" jdbcType="TIMESTAMP" property="created" /></resultMap><insert id="addWorkerNode" useGeneratedKeys="true" keyProperty="id"parameterType="com.uidgenerator.entity.WorkerNode">INSERT INTO WORKER_NODE(HOST_NAME,PORT,TYPE,LAUNCH_DATE,MODIFIED,CREATED)VALUES (#{hostName},#{port},#{type},#{launchDate},NOW(),NOW())</insert><select id="getWorkerNodeByHostPort" resultMap="BaseResultMap ">SELECTID,HOST_NAME,PORT,TYPE,LAUNCH_DATE,MODIFIED,CREATEDFROMWORKER_NODEWHEREHOST_NAME = #{host} AND PORT = #{port}</select>
</mapper>

可以通过mybatis生成工具直接生成文件和实体类，然后将插入和查询方法复制

注意修改resultMap中的type和insert中的keyProperty为自身项目的实体类地址

在application.yml文件中增加如下配置

mybatis:mapper-locations: classpath:mybatis/*.xml

3.6实体类

使用插件生成的实体类

3.7创建Mapper

@Mapper
public interface WorkerNodeMapper {int addWorkerNode(WorkerNode workerNodeEntity);WorkerNode getWorkerNodeByHostPort(@Param("host") String host, @Param("port") String port);}

3.8 Service

IWorkerNodeService接口

public interface IWorkerNodeService {public long genUid();
}

WorkerNodeServiceImpl实现类

@Service
public class WorkerNodeServiceImpl implements IWorkerNodeService {@Resourceprivate UidGenerator uidGenerator;@Overridepublic long genUid() {Long uu_id = UidGeneratorComponent.uu_id;return uidGenerator.getUID();}
}

3.8 Controller

@RestController
public class WorkerNodeServiceController {@Resourceprivate IWorkerNodeService workerNodeService;/*** 集成百度uid-generator生成id* @return*/@GetMapping("/baidu/uid")public long baiduUid(){long uid = workerNodeService.genUid();return uid;}
}

3.9 访问接口测试

http://127.0.0.1:8099/test/baidu/uid

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