美团开源的leaf：https://tech.meituan.com/2017/04/21/mt-leaf.html
github地址：https://github.com/Meituan-Dianping/Leaf

官方提供了两种方式，雪花算法和数据库。目前仅提供数据库方式获取分布式id.

引入依赖：

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!--leaf-core 核心依赖-->
        <dependency>
            <groupId>com.sankuai.inf.leaf</groupId>
            <artifactId>leaf-core</artifactId>
            <version>1.0.1</version>
            <exclusions>
                <exclusion>
                    <groupId>org.mybatis</groupId>
                    <artifactId>mybatis</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

         <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

spring:
    profiles:
        active: dev
    datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://33.33.33.33:3306/xxx?useUnicode=true&characterEncoding=utf8&useSSL=false&autoReconnect=true
        username: root
        password: 123
        initial-size: 5
        min-idle: 1
        max-active: 5
        max-wait: 60000
        time-between-eviction-runs-millis: 60000
        min-evictable-idle-time-millis: 30000
        max-evictable-idle-time-millis: 60000

@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})
@EnableDiscoveryClient
@EnableFeignClients
public class AppMain {
  SpringApplication app = new SpringApplication(AppMain.class);
  log.info("Registering ShutDonw Hook.");
  Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                log.info("Shutting down service, unregister from Eureka server!");
                DiscoveryManager.getInstance().getEurekaClient().shutdown();
            }
        });
}

import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import com.sankuai.inf.leaf.segment.SegmentIDGenImpl;
import com.sankuai.inf.leaf.segment.dao.impl.IDAllocDaoImpl;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = {"com.sankuai.inf.leaf.segment.dao", "com.xxx.xx.mapper"})
public class DataSourceConfig {

    @Autowired
    private Environment environment ;

    /**
     * 配置单表数据源
     * @return
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource(){
        return DruidDataSourceBuilder.create().build(environment, "spring.datasource");
    }

    @Bean
    public IDAllocDaoImpl idAllocDao(DataSource dataSource) {
        return new IDAllocDaoImpl(dataSource);

    }

    @Bean
    public SegmentIDGenImpl segmentIDGen(IDAllocDaoImpl idAllocDao) {
        SegmentIDGenImpl segmentIDGen = new SegmentIDGenImpl();
        segmentIDGen.setDao(idAllocDao);
        segmentIDGen.init();
        return segmentIDGen;

    }

}

import com.sankuai.inf.leaf.segment.model.LeafAlloc;
import org.apache.ibatis.annotations.Update;

public interface LeafAllocMapper {

    @Update("INSERT INTO leaf_alloc (biz_tag, max_id, step) values (#{key},#{maxId},#{step})")
    void create(LeafAlloc leafAlloc);
}

@RestController
@RequestMapping("/api")
public class IdGenServiceApi {

    private final Logger log = LoggerFactory.getLogger(IdGenServiceApi.class);

    @Autowired
    private SegmentIDGenImpl segmentIDGen;
    @Autowired
    private LeafAllocMapper leafAllocMapper;

    @GetMapping({"/getId"})
    public ResponseEntity<Result> getNextId(@RequestParam("biz") String biz) {
        Result result = segmentIDGen.get(biz);
        return ResponseEntity.ok(result);
    }

    @GetMapping({"/getIdBatch"})
    public ResponseEntity<List<Long>> getNextIdBatch(@RequestParam("biz") String biz, @RequestParam("count") Integer count) {
        if(count <= 0 || count > 200) {
            throw new Exception("获取失败");
        }
        List<Long> list = new ArrayList<>();
        for (int i = 0; i < count; i++) {
            Result result = segmentIDGen.get(biz);
            list.add(result.getId());
        }
        return ResponseEntity.ok(list);
    }


    @PostMapping("/create")
    public ResponseEntity<LeafAlloc> create(@RequestBody LeafAlloc leafAlloc) {
        leafAllocMapper.create(leafAlloc);
        return ResponseEntity.ok(leafAlloc);
    }

}

CREATE TABLE `leaf_alloc`  (
  `biz_tag` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',
  `max_id` bigint(20) NOT NULL DEFAULT 1,
  `step` int(11) NOT NULL,
  `description` varchar(256) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `update_time` timestamp(0) NOT NULL DEFAULT CURRENT_TIMESTAMP(0) ON UPDATE CURRENT_TIMESTAMP(0),
  PRIMARY KEY (`biz_tag`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;