转载 https://mp.weixin.qq.com/s/I9MnjiYasPqiKWVFdSUOjw

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。

Spring Boot 基础就不介绍了，新手请看这个学习教程和示例仓库：https://github.com/javastacks/spring-boot-best-practice

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;

报错信息如下:

image.png

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。MySQL 开发的 36 条军规建议看看。

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 {

    @Resource
    private WorkerNodeMapper workerNodeMapper;
    @Override
    @Transactional
    public 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 ">
        SELECT
            ID,
            HOST_NAME,
            PORT,
            TYPE,
            LAUNCH_DATE,
            MODIFIED,
            CREATED
        FROM
            WORKER_NODE
        WHERE
            HOST_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 {
    @Resource
    private UidGenerator uidGenerator;

    @Override
    public long genUid() {
        Long uu_id = UidGeneratorComponent.uu_id;
        return uidGenerator.getUID();
    }
}

3.8 Controller

@RestController
public class WorkerNodeServiceController {
    @Resource
    private 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

image.png
项目目录结构
image.png