MybatisPlus配置字符串雪花ID

在执行入库时，以防精度丢失大多人会擦用雪花算法生成字符串ID，可以从拦截器，yml全局配置等各方面去实现，下面将通过实现mybatisPlus的IdentifierGenerator 方式去实现。

自定义ID生成器，采用雪花机器算法

public class SnowflakeIdWorker {

    /**
     * 开始时间戳 (2020-01-01)
     */
    private final long twepoch = 1609459200000L;

    /**
     * 序列号占的位数
     */
    private final long sequenceBits = 12L;

    /**
     * 数据标识 ID 采用的位数
     */
    private final long machineBits = 5L;

    /**
     * 数据中心 ID 采用的位数
     */
    private final long datacenterBits = 5L;

    /**
     * 支持的最大机器 ID
     */
    private final long maxMachineId = -1L ^ (-1L << machineBits);

    /**
     * 支持的最大数据中心 ID
     */
    private final long maxDatacenterId = -1L ^ (-1L << datacenterBits);

    /**
     * 序列号最大值
     */
    private final long sequenceMask = -1L ^ (-1L << sequenceBits);

    /**
     * 机器 ID 左移位数
     */
    private final long machineIdShift = sequenceBits;

    /**
     * 数据中心 ID 左移位数
     */
    private final long datacenterIdShift = sequenceBits + machineBits;

    /**
     * 时间戳左移位数
     */
    private final long timestampLeftShift = datacenterIdShift + datacenterBits + machineBits;

    /**
     * 上次生成 ID 的时间戳
     */
    private long lastTimestamp = -1L;

    /**
     * 序列
     */
    private long sequence = 0L;

    /**
     * 机器 ID
     */
    private long machineId;

    /**
     * 数据中心 ID
     */
    private long datacenterId;

    /**
     * 构造函数
     *
     * @param datacenterId 数据中心ID
     * @param machineId    机器ID
     */
    public SnowflakeIdWorker(long datacenterId, long machineId) {
        // 检查 datacenterId 和 machineId 是否符合规定
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
            throw new IllegalArgumentException("datacenterId can't be greater than " + maxDatacenterId + " or less than 0");
        }
        if (machineId > maxMachineId || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than " + maxMachineId + " or less than 0");
        }
        this.datacenterId = datacenterId;
        this.machineId = machineId;
    }

    /**
     * 产生下一个 ID
     *
     * @return Long 类型的 ID
     */
    public synchronized long nextId() {
        long timestamp = System.currentTimeMillis();

        // 如果当前时间戳小于上次生成 ID 的时间戳，则发生时钟回拨
        if (timestamp < lastTimestamp) {
            throw new RuntimeException("Clock moved backwards. Refusing to generate id for " + (lastTimestamp - timestamp) + " milliseconds");
        }

        // 如果是同一毫秒内生成的 ID，序列号递增
        if (lastTimestamp == timestamp) {
            sequence = (sequence + 1) & sequenceMask; // 0 到 sequenceMask 之间循环
            if (sequence == 0) {
                // 如果序列号已用尽，等待下一毫秒
                timestamp = waitNextMillis(lastTimestamp);
            }
        } else {
            sequence = 0L; // 不同的时间戳重新开始生成
        }

        lastTimestamp = timestamp;


        long id = ((timestamp - twepoch) << timestampLeftShift) // 时间戳部分
                | (datacenterId << datacenterIdShift)         // 数据中心 ID 部分
                | (machineId << machineIdShift)               // 机器 ID 部分
                | sequence;
        // 组合成一个 ID
        return Math.abs(id);
    }

    /**
     * 等待直到下一毫秒
     *
     * @param lastTimestamp 上次生成 ID 的时间戳
     * @return 当前时间戳
     */
    private long waitNextMillis(long lastTimestamp) {
        long timestamp = System.currentTimeMillis();
        while (timestamp <= lastTimestamp) {
            timestamp = System.currentTimeMillis();
        }
        return timestamp;
    }

    private static class SnowflakeIdWorkerSingleton {
        private static final SnowflakeIdWorker INSTANCE = new SnowflakeIdWorker(1L, 1L); // 可配置 datacenterId 和 machineId
    }

    public static SnowflakeIdWorker getInstance() {
        return SnowflakeIdWorkerSingleton.INSTANCE;
    }

    public static void main(String[] args) {
        long l = SnowflakeIdWorker.getInstance().nextId();
        System.out.println(l);
    }
}

实现IdentifierGenerator方法

public class StringSnowflakeIdGenerator implements IdentifierGenerator {

    @Override
    public Number nextId(Object entity) {
        return SnowflakeIdWorker.getInstance().nextId();
    }

    @Override
    public String nextUUID(Object entity) {
        return String.valueOf(SnowflakeIdWorker.getInstance().nextId());
    }

}

配置springIOC

@Configuration(proxyBeanMethods = false)
public class MybatisPlusPageConfigurer implements WebMvcConfigurer {

    /**
     * SQL 过滤器避免SQL 注入
     * @param argumentResolvers
     */
    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new SqlFilterArgumentResolver());
    }

    /**
     * 分页插件
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

    /**
     * 审计字段自动填充
     * @return {@link MetaObjectHandler}
     */
    @Bean
    public MybatisPlusMetaObjectHandler mybatisPlusMetaObjectHandler() {
        return new MybatisPlusMetaObjectHandler();
    }

    @Bean
    public StringSnowflakeIdGenerator stringSnowflakeIdGenerator() {
        return new StringSnowflakeIdGenerator();
    }

}

配置字段

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class BSEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @TableId(value = "id",type = IdType.ASSIGN_ID)
    private String id;

    @TableField(value = "create_by", fill = FieldFill.INSERT)
    private String createBy;

    @TableField(value = "update_by", fill = FieldFill.INSERT_UPDATE)
    private String updateBy;

    @TableField(value = "create_time", fill = FieldFill.INSERT)
    private Date createTime;

    @TableField(value = "update_time", fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;

    @TableField(value = "deleted", fill = FieldFill.INSERT)
    private Integer deleted;

}

然后调用mybatisPlus框架的入库是机会自动生成字符串雪花ID