leijinjun/ID-Generator

Snowflake ID,ID生成器,雪花算法

ID-Generator

唯一ID生成器，支持使用数据库方式或雪花算法生成ID。

介绍

id-core包为id生成算法实现。 ID资源：指id源。如数据库、Redis、应用程序等可以产生ID的源。ID源需保证生产的ID在所需要的应用程序内唯一。

1. IdGenerator接口。定义获取全局唯一id。 SegmentIdBufferGenerator、SegmentIdDoubleBufferGenerator、SnowFlakeGenerator为其几种实现。SegmentIdBufferGenerator和SegmentIdDoubleBufferGenerator需要依赖外部ID资源。
2. IDResource接口。定义Id资源器。
3. SnowFlakeGenerator雪花ID生成器。

快速开始

id-extend模块

1.根据雪花算法生成ID

//单体应用程序case
final IdGenerator snowFlakeGenerator = new SnowFlakeGenerator();
final Long next = (Long) snowFlakeGenerator.next();
//集群
//其中workId通过接口WorkIdConfig获取
WorkIdConfig workIdConfig = new DatabaseWorkIdConfig();
SnowFlakeConfig snowFlakeConfig = new SnowFlakeConfig(timestampBits,workerIdBits,sequenceBits,workIdConfig.initWorkId());
IdGenerator snowFlakeGenerator = new SnowFlakeGenerator(snowFlakeConfig);

2.从数据库生成ID

/**
 * 基于Mysql的悲观锁ID资源器实现
 * @author leijinjun
 * @date 2021/10/7
 **/
@Service
public class DefaultIdSegmentResource {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Transactional(rollbackFor = Exception.class)
    public ID getIdSegment(String bizType) {
        final Stream<ConfigIdGenPO> stream = jdbcTemplate.queryForStream("select id,cur_id,step,`version` from c_id_gen where " +
                "biz_type = ? for update", new BeanPropertyRowMapper<>(ConfigIdGenPO.class), bizType);
        final ConfigIdGenPO configIdGenPo = Objects.requireNonNull(stream.findFirst().orElse(null), "configIdGenPO is null");
        Long curId = configIdGenPo.getCurId();
        Integer step = configIdGenPo.getStep();
        long maxId = curId + step;
        int update = jdbcTemplate.update("update c_id_gen set cur_id = ? , update_at = ? , version = version+1 where id = ? and version = ?",
                new Object[]{maxId, LocalDateTime.now(), configIdGenPo.getId(), configIdGenPo.getVersion()},
                new int[]{Types.BIGINT, Types.TIMESTAMP, Types.BIGINT, Types.BIGINT});
        return new IDSegment(curId, maxId);
    }

}

//创建id资源器
DefaultIdSegmentResource resource = new DefaultIdSegmentResource();
//将Id资源器与IdGenerator绑定
SegmentGenerator segmentGenerator = new SegmentIdBufferGenerator(()->resource.getIdSegment("bizType"));
or
SegmentGenerator segmentGenerator = new SegmentIdDoubleBufferGenerator(()->resource.getIdSegment("bizType"));
//获取id
segmentGenerator.next();

//对SegmentGenerator进行缓存
@Component
public class DefaultIdGen {

    private final Map<String, SegmentGenerator> segmentGeneratorMap = new HashMap<>();

    private final Map<String, IDResource> idResourceMap = new HashMap<>();

    private final DefaultIdSegmentResource resource;

    public DefaultIdGen(DefaultIdSegmentResource resource) {
        this.resource = resource;
    }

    public Object next(String businessType) {
        if (!segmentGeneratorMap.containsKey(businessType)) {
            synchronized (this) {
                if (!segmentGeneratorMap.containsKey(businessType)) {
                    idResourceMap.putIfAbsent(businessType, () -> resource.getIdSegment(businessType));
                    IDResource idResource = idResourceMap.get(businessType);
                    segmentGeneratorMap.putIfAbsent(businessType, new SegmentIdBufferGenerator(idResource));
                }
            }
        }
        final SegmentGenerator segmentGenerator = segmentGeneratorMap.get(businessType);
        return segmentGenerator.next();
    }
}